AMERICAN COLLEGE OF VETERINARY RADIOLOGY · PDF file(formerly known as the Resident Seminar) Digital Radiography, PACS, DICOM, ... For Digital Radiography, ... AMERICAN COLLEGE OF

AMERICAN COLLEGE OF VETERINARY RADIOLOGY

Annual Scientific Conference

October 21-25, 2008

CROWNE PLAZA RIVERWALK SAN ANTONIO, TEXAS

Program Committee Brian A. Poteet, Program Chair William Hornof, Program Co-Chair – Image Interpretation Session Andra Voges, Program Co-Chair – Forum Focus on Diagnostic Imaging Tod Drost, President, NM Society Section Jon Shiroma, President, Ultrasound Society Section Russ Tucker, President, CT/MRI Society Section Susie Wilson, ACVR Administrator Jessica Winger, ACVR Meeting Manager

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Note

Use the bookmarks on the left and the blue underlined links within the document to navigate throughout the program. The 'Next' and 'Previous' Page and the 'Next' and 'Previous' View are also very useful for navigation. The 'Previous' view can be used as a 'Back' button after clicking on a link to view an abstract. Note: You can make the Previous View button and Go To Next View button available in the Adobe Reader toolbar area by right-clicking/Control-clicking the Page Navigation toolbar and choosing them in the context menu, or choosing Show All Tools.

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Table of Contents

I. 2008 Conference General Information.......................................................... 4 Hotel floor plan

Registration will be in the Texas Ballroom Foyer daily

II. Corporate Partners........................................................................................5 Aloka Ultrasound Asteris Inc. Advanced Veterinary Technologies, Inc. CoActiv PACS4VETS Eklin Medical Systems Elsevier Fovea DR Idexx Digital Imaging Innovet/Summit Industries Orthopedic Foundation for Animals Sedecal USA Siemens Medical Solutions Sound Technologies TW Medical Veterinary Supply Ultrasource/Eklin Ultrasound Division Universal Medical Systems Universal Ultrasound Vetel Diagnostics Wiley-Blackwell III. Program Overview......................................................................................14

IV. Tuesday, October 21, 2008........................................................................19 Forum Focus on Diagnostic Imaging Lecture Series (formerly known as the Resident Seminar) Digital Radiography, PACS, DICOM, RIS/HIS, Teleradiology Voges, Hornof, Wright, Poteet

V. Wednesday, October 22, 2008....................................................................20

Ultrasound Society Business Meeting - Shiroma Welcoming Remarks and Introductions - Poteet ACVR Presidential Address - Drost ACVR Keynote Speaker Address – Mann Diagnostic Ultrasound Keynote Speaker Address - Ophir Diagnostic Ultrasound Scientific Sessions – Shiroma General Radiology Scientific Session - Drost Opportunity to Meet the Resident Coordinators Evening Reception sponsored by Orthopedic Foundation for Animals

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VI. Thursday, October 23, 2008........................................................................40

Nuclear Medicine Society Business Meeting - Drost Nuclear Medicine Scientific Session - Drost Nuclear Medicine – Focus on Portosystemic Shunts ACVR Film Interpretation Session - Hornof Resident Authored Paper and Grant Awards - Drost Confirmation and Recognition of New ACVR Diplomates – Drost/Poteet ACVR Business Meeting (Diplomates Only) – Hornof

VII. Friday, October 24, 2008.............................................................................47 CT/MRI Society Business Meeting – Tucker CT/MRI Keynote Speaker Address - Laredo CT/MRI Scientific Session – Tucker Scientific Poster Presentations “Veterinary Radiology Training at UC Davis – 1970 – 2007” – T. O’Brien CT/MRI Scientific Session, Continued – Tucker

VIII. Saturday, October 25, 2008.........................................................................75 VRTOG Business Meeting Radiation Oncology Presidential Address – Prescott Radiation Oncology Keynote Speaker Address – Thames RO Business Meeting RO Scientific Sessions 2008 Program Adjournment

IX. Special Activities...........................................................................................89 X. Conference Registrants................................................................................90

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THE AMERICAN COLLEGE OF VETERINARY RADIOLOGY GRATEFULLY ACKNOWLEDGES THE SUPPORT OF THE

FOLLOWING COMPANIES AND WISHES TO THANK THEM FOR THEIR CONTRIBUTIONS

(As of Friday, September 12, 2008)

ALOKA ULTRASOUND

10 Fairfield Blvd Wallingford, CT 06492

Phone: (203) 269- 5088 Toll Free: (800) 872-5652

Fax: (203) 269-6075 Email: [email protected] Website: www.aloka.com

ALOKA has a full range of ultrasound systems for most veterinary applications. The super premium Alpha 7 and premium Alpha 5 offer superb image quality for the most challenging cases. We also offer cost effective solutions in the Prosound-6, SSD-3500, and SSD-4000. Our two portables, the SSD-500 and SSD-900 are reliable, rugged systems that are ideal for large animal reproduction, equine tendons and, with the 500, food animal live carcass evaluation. With the addition of the Sonosite family of battery operated lightweight systems, Aloka can now provide a system so portable you can carry it in a briefcase.

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ASTERIS, INC. P.O. Box 285

Stephen Town, NY 12168 Phone: (877) 727-8374

Fax: (877) 488-6746 Email: [email protected]

ASTERIS is an innovative, progressive firm focusing on technology solutions for the veterinary practitioner. Founded in 2004, ASTERIS delivers inimitable PACS (Picture Archiving and Communications Systems) solutions and a groundbreaking veterinary information communication platform. A revolutionary concept, ASTERIS Veterinary Communication Network (VCN) enables veterinary practices, practitioners, and clients to access and share the full breadth of patient medical data at any time, from anywhere in the world.

ADVANCED VETERINARY TECHNOLOGIES, INC. P.O. Box 4099

New Windsor, NY 12553 Phone/ Fax: (877) 428-8674

Email: [email protected] Website: www.avtmri.com

Advanced Veterinary Technologies, Inc. designs, engineers and manufactures radiology equipment specifically for veterinary use. AVT’s novel Animal-Conscious Technology™ -technology designed with the veterinary patient in mind- combines customized engineering with clinical input from veterinarians to provide cost effective, advanced technologies for the veterinarian and their patient.

COACTIV PACS4VETS 900 Ethan Allen Highway

Ridgefield, CT 06877 Phone: (203) 894-1651

Email: [email protected]

CoActive Medical develops and markets a complete line of PACS and Medical Imaging products and services for the management of digital radiography images. CoActiv has designed PACS4VETS®, a state-of-the-art PACS, based on EXAM-PACS®, CoActiv’s human PACS, which enables veterinarians to view, manage, distribute and archive exams produced by imaging modalities. CoActiv is dedicated to delivering affordable and easy-to-use digital imaging management tools to the veterinary profession, resulting in improved diagnostic capabilities that also have FDA and HIPAA certification.

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EKLIN MEDICAL SYSTEMS 1605 Wyatt Drive

Santa Clara, CA 95054 Toll Free: (800) 819-5538 Website: www.eklin.com

Eklin’s Digital Practice™ system- RapidStudy™ Digital Radiology, RapidStore™ Multi-Modality PACS and VIA+™ Practice Management- is designed for every veterinary practice. Complete radiographic exams are completed in minutes and quickly integrated with any DIOCOM- compliant studies such as CR, MRI, ultrasound and CT. Experience unprecedented workflow plus the gold standard in “best practice” medical care- all backed by Eklin’s professional service, training and support.

ELSEVIER 25607 Singing Rain

San Antonio, TX 78260 Phone: (210) 497-3198

Email: [email protected] Website: (210) 497-3198

SAUNDERS, MOSBY, CHURCHILL LIVINGSTONE, BUTTERWORTH HEINEMANN AND HANLEY BELFUS, a combined premier worldwide health science publishing company, now under the umbrella of ELSEVIER, INC., proudly presents our latest titles. Come visit us at our booth and browse through our complete selection of publications including books, periodicals and software. ELSEVIER, INC. - building insights, breaking boundaries.

FOVEA DR

P.O. Box 1908 1233 N. Ashley Nixa, MO 65714

Toll Free: (888) 368-3201 Email: [email protected]

Website: www.FoveaDR.com Fovea Direct Digital Radiography has reset the bar in veterinary x-ray. The entire line of Fovea systems has been designed and built from the ground up to be truly digital. Fovea offers the highest resolution and the fastest DR, with the lowest dose available. Cutting-edge technology, top-of-the-line equipment, and the ability to look ahead and anticipate the demands of veterinarians and their practices have helped cement Fovea’s position as the industry leader. Fovea DR provides factory direct pricing, installation and a friendly support staff from our facility in America’s heartland.

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IDEXX DIGITAL IMAGING One Idexx Drive

Westbrook, ME 04092 Phone: (207)-556-3300 Mobile: (207) 239-9055


IDEXX Digital Imaging- to meet the diverse needs of any veterinary practice, IDEXX offers a full range of digital imaging solutions that were developed in conjunction with independent, board certified veterinary radiologists specifically for veterinary use. The IDEXX-DR™ 1417 and IDEXX-CR™ 1417 Digital Imaging systems can help your practice increase revenue, eliminate film associated expenses and improve productivity by streamlining workflow, in addition to increasing your diagnostic capabilities. Both systems offer complete integration through IDEXX SmartLink™ Digital Imaging with IDEXX Cornerstone® so you can get information where you need it, when you need it.

INNOVET/ SUMMIT INDUSTRIES 2901 W. Lawrence Ave

Chicago, IL 60625 Phone: (866) 462-4311

Email: [email protected] Website: www.innovet4vets.com

InnoVet™, the most trusted name in veterinary radiographic systems, now offers affordable digital solutions with the simplicity, reliability and support you expect. Digital imaging can now be added to the InnoVet™ radiographic system you already own or plan to purchase using our InnoVet DVM. For the ultimate in digital imaging, the InnoVet DXR is a complete solution. InnoVet™ by Summit Industries in Chicago celebrates over 20 years of designing and manufacturing state-of-the-art radiography systems. For all the details, visit our booth or website www.innovet4vets.com.

KINGSBRIDGE VETERINARIAN EQUIPMENT TECHNOLOGY SOLUTIONS, LLC. 150 N. Field Dr.

Suite 193 Lake Forest, IL 60045

KingsBridge/VETS is the premier provider of refurbished CT, MRI, Ultrasound and other high technology imaging equipment serving the veterinary market. Our meticulous refurbishment process insures that every product meets the highest standards of performance and quality. Each product carries a full one year warranty and is guaranteed to meet original performance specifications. KingsBridge/VETS also offers creative financing and rental programs that allow any veterinary practice to have high quality, high technology diagnostic equipment at its clinic.

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ORTHOPEDIC FOUNDATION FOR ANIMALS 2300 E. Nifong Blvd.

Columbia, MO 65201-3806 Toll Free: (800) 442-0418 ext. 221


Established as a not-for-profit organization in 1966, the OFA has funded over 2 million dollars towards animal wellness. The OFA has evolved from solely a hip registry into genetic counseling for hip and elbow dysplasia, congenital cardiac disease, autoimmune thyroiditis, patella luxation, copper toxicosis, von Willerbrand’s disease, phosphofructorkinase deficiency, pyruvate deficiency and rod/cone dysplasia.

SEDECAL USA, INC.

2920 North Arlington Heights Rd Arlington Heights, IL 60004

Phone: (847) 394-6960 Email: [email protected]

Vet-ray Technology by Sedecal: “Gold Standard” for Veterinary X-ray technology. Sedecal offers the most complete line of Veterinary Specific X-ray Machines: Basic Vet, Standard Vet, Premium Vet, Digital Vet, Fluoro Vet, Mobile Vet and Large Animal Rooms. All Sedecal Units are High Frequency. Vetray Digital Vet DX offers the industries only “One Touch” Touch Screen Display for 6 sec. image display and Generator Controls, largest image size: 17 x 17, 500mA High Frequency, 40kW Generator, 4 way float top, hands free collimater light control, the “easiest to use” Digital system on the market today.

SIEMENS MEDICAL SOLUTIONS 51 Valley Stream Pkwy

Malvern, PA 19355 Toll Free: (888) 826-9702

Website: www.usa.seimans.com/medical

The Siemens Healthcare Sector is one of the world’s largest suppliers to the healthcare industry. The company is a renowned medical solutions provider with core competence and innovative strength in diagnostic and therapeutic technologies as well as knowledge engineering, including information technology and system integration. With its laboratory diagnostics acquisitions, Siemens Healthcare is the first integrated healthcare company, bringing together imaging and lab diagnostics, therapy, and healthcare information technology solutions, supplemented by consulting and support services. Siemens Healthcare delivers solutions across the entire continuum of care- from prevention and early detection, to diagnosis, therapy and care.

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SOUND TECHNOLOGIES, INC. 5817 Dryden Place, Suite 101

Carlsbad, CA 92008 Phone: (760) 448-4842


Sound Technologies is the veterinary industry’s largest and most trusted imaging partner. For Digital Radiography, Ultrasound, Distributed Imaging, or Education, Sound can provide you with the most powerful and cost effective solution. Sound will deliver solutions that simplify and enhance diagnostic imaging to help your practice thrive.

TW MEDICAL VETERINARY SUPPLY 3610 Lohman Ford Rd Lago Vista, TX 78645

Phone: (888) 787-4483 ext 118 Email: [email protected] Website: www.veterinaryct.com

TW Medical Veterinary Supply is your expert source for advanced veterinary imaging equipment. We provide complete solutions for CT, MRI, and Nuclear Medicine. TW Medical specializes in providing veterinary clinics with the latest technology at affordable prices. We can provide complete solutions, including delivery, installation, training, support and maintenance. We offer a variety of programs to help get you up and running with the veterinary imaging equipment, including purchase, lease, rental and pay-per-procedure options.

ULTRASOURCE / EKLIN ULTRASOUND DIVISION 929 Alpine Commerce Park Ct, Suite 100

Grand Rapids, MI 49544 Phone: (616) 647-3401


Ultrasource is now part of Eklin! Together we will continue to bring you the highest resolution ultrasound technology. Whether your needs are abdominal or cardiac, Philips Ultrasound has a system for you. Combining the strong legacy of ATL and HP ultrasound, Philips is redefining the term “state of the art” with iU22, iE33, HD15, HD11XE, HD7 and HD3. Large animal and mixed practice systems are also available. Complete education and telemedicine packages included with every system.

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UNIVERSAL MEDICAL SYSTEMS

29500 Aurora Rd, Unit 16 Solon, OH 44139

Phone: 440-349-3210 Fax: 440-498-2188

Email: [email protected] Website: www.veterinary-imaging.com

Universal Medical Systems, Inc. of Ohio is the only authorized distributor serving the veterinary market selling CT and MRI scanners directly from the major manufacturers designed specifically to meet your needs. New or certified systems are available with a variety of financing and service options. Visit us today and see for yourself how we scan every animal in less than 30 seconds.

UNIVERSAL ULTRASOUND 299 Adams St

Bedford Hills, NY 10507 Toll Free: 800-842-0607

Fax: 914-666-2454 Email: [email protected]

Website: http://www.univeralultrasound.com

Universal Ultrasound has been the leading supplier of veterinary ultrasound for over 25 years. We have partnered with over 10,000 veterinarians to bring imaging diagnostic capabilities into their practices confidently and affordably. Universal Ultrasound offers the largest variety of ultrasound packages for both beginning and advanced users, featuring all digital technology, portability, cardiac and abdominal enhancements, comprehensive training, and advanced archiving and telemedicine options. See the difference ultrasound can make to how you practice medicine today.

VETERINARY INFORMATION NETWORK (VIN)

800-700-4636 Email: [email protected]

Website: www.VIN.com

The Veterinary Information Network (VIN) is the premier online community, continuing education, and information resource for veterinarians. Founded in 1991, VIN reaches over 32,000 veterinarians, veterinary students, and industry partners worldwide. VIN is the leader in unlimited access to medical, product and practice management information. For a FREE one-month trial membership, join us at www.VIN.com, phone 800-700-4636, or email [email protected]. Let us show you why VIN is the BEST online resource for veterinarians. VIN will provide a free Cyber Café at the 2008 ACVR Annual Scientific Meeting, so please stop by to check your Email, surf the web, and try VIN.

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VETEL DIAGNOSTICS 4850 Davenport Creek Rd

San Luis Obispo, CA 93401 Phone: (805)781-7691


Website: www.veteldiagnostics.com

VETEL Diagnostics offers veterinarians advanced diagnostic technologies including Envision, Explorer and Empower Digital Radiography Systems. Vetel’s digital radiography systems were developed specifically for veterinarians with a focus on intuitive, user-friendly software and excellent image quality. System models include multiple companion animal configurations with a variety of panel sizes, available installed in a table or in a rugged portable case. Vetel’s DR systems have the widest dynamic range available and are complete imaging systems with multiple image algorithms per view, image enhancement tools, accurate measurement tools and easy report generation. FLIR thermal imaging systems are revolutionizing veterinary medicine helping to diagnose difficult cases. Thermography applications include lameness diagnostics, pre-purchase exams, saddle fit evaluation and back pain detection.

WILEY- BLACKWELL 2121 State Ave Ames, IA 50014

Phone: 800-434-3422 Fax: 800-597-3299

Email: [email protected] Website: www.wiley.com

Wiley-Blackwell, the scientific, technical, medical and scholarly publishing business of John Wiley & Sons, is the world’s leading society publisher in Veterinary medicine. W-B offers peer-reviewed primary research and evidence-based medicine across thousands of online journals, books, reference works, and databases. A conference discount is being offered to all attendees at our booth.

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American College of Veterinary Radiology

Special Thanks to the following Corporate Partners:

2008 Conference Bag Sponsor CoActiv PACS 4 Vets

Badge Neck Lanyards Sponsor Universal Ultrasound

Cyber Café Veterinary Information Network (VIN)

ACVR Reception Sponsors Orthopedic Foundation for Animals

Universal Medical Systems, Inc.

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AMERICAN COLLEGE OF VETERINARY RADIOLOGY Annual Scientific Conference

October 21-25, 2008 CROWNE PLAZA RIVERWALK

SAN ANTONIO, TEXAS

Program Overview Tuesday, October 21, 2008 7:00 am Registration opens 8:00 am Forum Focus on Diagnostic Imaging Lecture Series – Introductory

Comments (10 minutes) - Voges 8:10 – 9:00 am Digital Radiography Basics (50 minutes) - Hornof 9:10 – 10:00 am Image Processing Techniques and Artifacts (50 minutes) - Hornof 10:00 – 10:30 am Break (30 minutes) 10:30 – 11:20 am Digital Radiography Systems (50 minutes) -Wright 11:30 – 12:20 pm DICOM (50 minutes) - Wright 12:20 – 1:30 pm Lunch (70 minutes) 1:30 – 2:20 pm Teleradiology (50 minutes) - Wright 2:30 – 3:20 pm Picture Archival and Communication Systems (PACS) (50 minutes) - Poteet 3:30 – 4:00 pm Break (30 minutes) 4:00 – 4:50 pm RIS/HIS Systems (50 minutes) - Poteet 4:50 – 5:00 pm Question and Answers (10 minutes) 5:00 pm Adjourn for the day

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Wednesday, October 22, 2008 7:15 am Ultrasound Society Business Meeting – Shiroma 8:00 am Welcoming Remarks and Introductions for 2008 ACVR Meeting - Poteet 8:15 am ACVR Presidential Address – Drost 9:00 am ACVR Keynote Speaker Address “Working Dogs in the 21st Century” - Mann 10:30 am Break with Exhibitors 11:00 am Diagnostic Ultrasound Keynote Speaker Address “Elastography – Imaging the Elastic Properties of Tissues Using

Ultrasound” - Ophir 12:00 pm Lunch 1:30 pm Diagnostic Ultrasound Scientific Session 3:00 pm Break with Exhibitors 3:30 pm General Radiology Scientific Session 5:42 pm Opportunity to Meet the Resident Coordinators 6:30 pm Reception sponsored by Orthopedic Foundation for Animals

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Thursday, October 23, 2008 7:15 am Nuclear Medicine Society Business Meeting – Drost 8:00 am Nuclear Medicine Scientific Session – Drost 9:30 am Break with Exhibitors 10:30 am Nuclear Medicine – Focus on Portosystemic Shunts - Drost 12:00 pm Lunch 1:30 pm ACVR Film Interpretation Session - Hornof 3:00 pm Break with Exhibitors 3:20 pm Resident Authored Paper and Grant Awards - Drost 3:30 pm Confirmation and Recognition of New ACVR Diplomates – Drost/Poteet 4:30 pm ACVR Business Meeting (Diplomates Only) – Pechman 6:30 pm Adjourn for the day

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Friday, October 24, 2008 7:15 am CT / MRI Society Business Meeting – Tucker 8:00 am CT / MRI Keynote Speaker Address “Imaging of Arthritis Using Traditional and Non-traditional Radiological

Methods” - Laredo 10:00 am Break with Exhibitors 10:30 am CT / MRI Scientific Session I – Tucker 12:00 pm Lunch 1:00 pm Poster Presentation Session 1:30 pm “Veterinary Radiology Training at UC Davis – 1970 – 2007” – T. O’Brien 2:00 pm CT / MRI Scientific Session II – Drost 3:30 pm Break with Exhibitors 4:00 pm CT / MRI Scientific Session III – Drost 5:00 pm Adjourn for the day

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Saturday, October 25, 2008 7:15 am VRTOG Business Meeting 8:00 am Radiation Oncology Presidential Address – Prescott 8:30 am Radiation Oncology Keynote Speaker Address “Altered Fractionation in Radiation Oncology” - Thames 10:30 am Break 11:00 am RO Scientific Session I 12:00 pm Lunch 1:00 pm RO Business Meeting 2:00 pm Break 2:30 pm RO Scientific Session II 5:00 pm Adjourn 2008 ACVR Scientific Meeting

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2008 ACVR Scientific Conference

Tuesday, October 21, 2008 7:00 am Registration opens 8:00 am Forum Focus on Diagnostic Imaging Lecture Series – Introductory

Comments (10 minutes) - Voges 8:10 – 9:00 am Digital Radiography Basics (50 minutes) - Hornof 9:10 – 10:00 am Image Processing Techniques and Artifacts (50 minutes) - Hornof 10:00 – 10:30 am Break (30 minutes) 10:30 – 11:20 am Digital Radiography Systems (50 minutes) -Wright 11:30 – 12:20 pm DICOM (50 minutes) - Wright 12:20 – 1:30 pm Lunch (70 minutes) 1:30 – 2:20 pm Teleradiology (50 minutes) - Wright 2:30 – 3:20 pm Picture Archival and Communication Systems (PACS) (50 minutes) - Poteet 3:30 – 4:00 pm Break (30 minutes) 4:00 – 4:50 pm RIS/HIS Systems (50 minutes) - Poteet 4:50 – 5:00 pm Question and Answers (10 minutes) 5:00 pm Adjourn for the day

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Wednesday, October 22, 2008 7:15 am Ultrasound Society Business Meeting 8:00 am Welcoming Remarks – Dr. Brian A Poteet, 2008 Program Chair 8:15 am ACVR Presidential Address – Dr. Tod Drost, ACVR President 9:00 am ACVR Keynote Speaker Address “Working Dogs in the 21st Century” – Dr. Kelly Mann, LTC, US Army,

DACVR 10:30 am Break with exhibitors 11:00 am Diagnostic Ultrasound Keynote Speaker Address “Elastography – Imaging the Elastic Properties of Tissues Using

Ultrasound” - Dr. Jonathan Ophir, PhD 12:00 pm Lunch 1:30 pm Scientific Session 1: Diagnostic Ultrasound

Moderator: Shiroma 1:30 pm Ultrasound-Guided Paravertebral Brachial Plexus Injections – Bagshaw 1:42 pm The Clinical Significance of Sonographically - Detected Renal Pelvic

Dilatation in Dogs and Cats – D’Anjou 1:54 pm Ultrasonographic Evaluation of Adrenal Gland Size in Small Breed Dogs:

Comparison with Pituitary Dependent Hyperadrenocorticism - Kim 2:06 pm Ultrasonography of the Canine Renal Pelvis at Various Intravenous Fluid

Rates - Laas 2:18 pm The Effect of Mitral Valve Regurgitation in Dogs on the Left Ventricular

Septum - Lord 2:30 pm Differentiation of Primary from Metastatic Hepatic Nodules in Dogs Using

Contrast-Enhanced Harmonic Ultrasound - Olivera 2:42 pm Ultrasound Imaging of the Inguinal Region of Adult Male Loggerhead Sea

Turtles (Caretta caretta) - Pease

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3:00 pm Break with Exhibitors 3:30 pm Scientific Session 2: General Radiology Moderator: TBD 3:30 pm Comparison of Radiography and Ultrasonography to Detect

Osteochondrosis Lesions in the Equine Tarsocural Joint – Alexander 3:42 pm Comparison of Conventional Myelography and Post-Myelography

Computed Tomography for the Evaluation of Canine Compressive Myelopathy – Childs

3:54 pm Quality of Excretory Urography Using a Low Dose of Iohexol: A Pilot

Study – David 4:06 pm Radiographic Imaging of the Equine Temporomandibular Joint – Ebling 4:18 pm Myelography Versus Computed Tomography in the Evaluation of Acute

Intervertebral Disk Extrusion in Chondrodystrophic Dogs – Hecht 4:30 pm Comparison of Ultrasound - Guided Trans-Splenic Portography with

Transplenic Portal Scintigraphy in Normal Dogs – Heffelman 4:42 pm Serial Postmortem Thoracic Radiography Findings and Canine Cadavers

– Heng 4:54 pm Can Image Processing in Digital Radiography Compensate for the Use of

an Anti-Scatter Grid? – Lo 5:06 pm Computed Tomographic Features of Respiratory Anatomy and Pathology

of the Whooping Crane (Grus Americana) – Schwarz 5:18 pm Development of Digital Multimedia Radiology Teaching Files – Tyson 5:30 pm The Effect of Manual Inflation Versus Spontaneous Inspiration on the

Cardiac Silhouette in Dogs - Webster 5:42 pm Opportunity to Meet the Resident Coordinators 6:30 pm Reception: Sponsored by Orthopedic Foundation for Animals

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ULTRASOUND-GUIDED PARAVERTEBRAL BRACHIAL PLEXUS INJECTIONS. H.Bagshaw, P. Larenza, G. Seiler. University of Pennsylvania School of Veterinary Medicine, PA, 19104. Introduction/Purpose: Local anesthesia of the brachial plexus is currently limited to the distal portion of the thoracic limb as the nerve roots are difficult to reach using conventional or electrostimulation techniques. Ultrasound-guidance of local anesthesia has been shown to significantly reduce morbidity and failure rates in human medicine. Descriptions of ultrasound-guidance for paravertebral injections have not been published in the veterinary literature. The purpose of this study was to establish the technique and ultrasonographic landmarks and to determine the precision of ultrasound-guided paravertebral injections around the brachial plexus nerve roots in the dog. Methods: Ultrasound landmarks for locating and imaging the C6, C7 and C8 cervical segmental spinal nerve roots were established initially using a cervical spine immersed in Jello and then using a whole cadaver that was subsequently dissected. Ten canine cadavers of varying sizes were imaged using the established landmarks with a 8MHz microcurved probe and a GE logiq9 ultrasound system. In each cadaver, a small volume (0.3ml) of a mix of Iohexol and methylene blue was injected at the level of the C6, C7 and C8 nerve roots on the left side of the neck to assess precision of the injections. A set of large volume (3.0ml) injections was performed on the right side to assess spread of the contrast. Computed Tomography was performed immediately after each set of injections. Proximity of the small volume injections to the nerve roots was determined by measuring the distance from the medial aspect of each nerve root foramen to the nearest edge of contrast. Spread of contrast was measured after the large volume injections in a cranial-to-caudal direction. Each cadaver was then dissected and staining of the targeted nerve roots was visually confirmed.

Results: The best ultrasonographic landmarks for guiding paravertebral injections were the transverse processes of C5, C6 and C7 and the dorsal and ventral scalenus muscles. The nerve roots were visualized in all dogs. The mean distance of the small volume injections from the foramina was 9mm (SD 5.9mm). The mean length of cranial to caudal spread of the large volume injections was 7.4cm (SD 1.7cm). Upon dissection, all injections resulted in staining of the targeted nerve roots. The phrenic nerve was stained in two of the ten cadavers when using a large volume of contrast. Discussion/Conclusions: This study describes the ultrasonographic landmarks for imaging the proximal nerve roots of the brachial plexus in the dog and demonstrates that ultrasound guidance can be used to perform paravertebral injections around the brachial plexus nerve roots. The measured mean distance of the injections from the intervertebral foramina resulted in placement of the aliquots within the sheath formed by the dorsal and ventral scalenus muscles, which is the targeted region for many types of brachial plexus block in human medicine. This method may be used in the dog to guide local anesthetic injections around the proximal nerve roots of the brachial plexus, resulting in anesthesia of the entire thoracic limb and shoulder. Unilateral phrenic nerve anesthesia has been reported in the veterinary literature, but is not associated with significant clinical problems. Adjustment of anesthetic dose may help to minimize spread of the anesthetic to the phrenic nerve. The described landmarks may also be useful to image the nerve roots in patients with suspected brachial plexus tumors.

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THE CLINICAL SIGNIFICANCE OF SONOGRAPHICALLY-DETECTED RENAL PELVIC

DILATATION IN DOGS AND CATS. M.A.d’Anjou, A. Bédard, M. Dunn, Department of clinical sciences, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Quebec, Canada J2S 7C6. Introduction/Purpose: Dilatation of the renal pelvis can be observed with ultrasonography in normal cats and dogs, as well as in animals with different types of obstructive and non-obstructive renal disorders. However, the magnitude of pelvic dilatation that can occur in different categories of renal disorders has not been previously reported in dogs or cats. Our goal was to establish renal pelvic width values (mm) in dogs and cats without signs of renal disorders, and to compare these values to those in animals with different types of obstructive and non-obstructive renal disorders. Methods:

A search through sonographic reports (2006-2008) was conducted. Animals in which a dilatation of the renal pelvis was recorded and in which high-quality transverse sonograms that included pelvic width (PW) measurement were obtained were retrospectively reviewed. Dogs and cats were categorized according to their renal function status (blood chemistries and urine analysis and culture) and whether increased diuresis (e.g. IV fluids, diuretics, etc) was clinically suspected or not. Animals with pyelonephritis, outflow obstruction or miscellaneous non-obstructive anomalies were grouped separately. When both kidneys were similarly categorized, only the maximal PW was considered for statistical analysis.

Results: A total of 82 dogs and 66 cats met the inclusion criteria and were divided into 7 groups. Mean PW (range) was 2.0mm (1.0-3.8) in 11 dogs and 1.8mm (0.08-0.32) in 10 cats with clinically-normal renal function and without evidence of increased diuresis, and 2.5mm (1.3-3.6) in 15 dogs and 2.3mm (1.1-3.4) in 16 cats with clinically-normal kidneys but increased diuresis. Mean PW was 5.6mm (1.9-12) in 9 dogs and 4.6mm (1.7-12.4) in 7 cats with pyelonephritis. Other types of acute or chronic renal disorders were associated with a PW of 3.4 mm (0.5-11) in 33 dogs and 3.0mm (1.2-7.3) in 13 cats. Partial or complete outflow obstructive resulted in a PW of 25mm (5.1-76) in 6 dogs and 11mm (1.2-39) in 17 cats, while miscellaneous non-obstructive anomalies (e.g. ectopic ureter) resulted in PW of 4.2mm (1.2-7.6) in 8 dogs and 3 cats. There was no significant difference between categories in dogs or cats (p 0.0024). Discussion/Conclusions:

Pelvic dimension is often used as a decision criterion in the sonographic assessment of kidneys of dogs and cats. While previous reports relied on a subjective assessment of pelvic width, our results establish measurement values that can be expected in dogs and cats with and without variable renal disorders. Our results confirm that renal pyelectasia can be encountered in animals with normal renal function and that it tends to increase with enhanced diuresis, renal diseases such as nephritis and pyelonephritis, or outflow obstruction. Moreover, these results demonstrate that pelvic width can exceed 2mm in animals with normal renal function and that it can be minimal (1mm) with partial outflow obstruction. Thus, the clinical significance of pelvic dilatation, regardless of its magnitude on ultrasonography, should be interpreted with caution.

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ULTRASONOGRAPHIC EVALUATION OF ADRENAL GLAND SIZE IN SMALL BREED DOGS: COMARISON WITH PITUITARY DEPENDENT HYPERADRENO-CORTICISM. Choi JH1 , Kim ME2, Kim HW1, Yoon JH.2 1Haemaru Referral Animal Hospital, Gyeonggi-do, 463-050. 2College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Seoul, 151-742, South Korea. Introduction/Purpose: Ultrasonography has been used as a sensitive and specific screening test of adrenal gland and ultrasonographic characteristics about size, shape and echogenicity of normal and abnormal adrenal gland have been described in dogs. The width of adrenal gland is reported as the most significant parameter compared with length and thickness and a 7.5mm has been used as an upper limit of the width of normal adrenal gland. However, it is controversial whether normal width of adrenal gland is consistent regardless of bodyweight. Moreover, small breed dogs are popular in Korea. In this study the normal upper limit of adrenal gland width particularly, in small breed dog was investigated. Methods: Small breed dogs, less than 10kg, performed serum chemistry and abdominal ultrasonography in Haemaru animal referral hospital with retrospective study from Jan. 01, 2006 to Jan. 10, 2008. Dogs were divided into two groups: normal dogs and dogs with pituitary-dependent hyperadrenocorticism (PDH). Results: One hundred eighty-nine dogs of 14 different small breeds were enrolled in the normal adrenal gland group; median gland width was 4.20 mm. Twenty-four dogs were enrolled in the PDH group; median gland width was 6.50 mm. The cut-off value between the width of normal adrenal glands and that of PDH adrenal glands was 6.0 mm with a sensitivity and specificity of 75% and 94%, respectively. The adrenal gland appeared as a peanut shape with homogeneous hypoechoic parenchyma in normal dogs and in most dogs with PDH, as well. Discussion/Conclusions: The result of this study suggests that the normal adrenal gland size in small breed dogs is smaller than previously reported. We believe that a cut-off of 6.0 mm may be used as the criterion for differentiating normal adrenal gland from adrenal hyperplasia.

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ULTRASONOGRAPHY OF THE CANINE RENAL PELVIS AT VARIOUS INTRAVENOUS FLUID RATES. C.A. Laas, P.M. Frank. UGA VTH, GA, 30602. Introduction/Purpose: Renal pyelectasia is a common finding during renal ultrasonography. Pyelectasia has been reported secondary to hydronephrosis, pyelonephritis, trauma, and in mild cases, intravenous (I.V.) fluid therapy. 1,2 The extent of pyelectasia secondary to I.V. fluid therapy has not been well defined.1,2 Defining the exact effects of I.V. fluid therapy on the appearance of the renal pelvis is crucial in avoiding potentially unnecessary diagnostics or treatments in the case of iatrogenic pyelectasia, and when pyelectasia is secondary to a disease process, appropriate therapy can be promptly implemented. The purposes of this research are: 1) to describe a standard site and technique for objective renal pelvis mensuration and 2) to objectively characterize the onset, progression, and resolution of iatrogenic pyelectasia at variable, clinically relevant fluid rates. Methods: Five healthy mongrel dogs received I.V. saline at 1, 2, and 3 times maintenance for 8 hours in three fluid therapy sessions. Each session was separated by 5 days without fluid administration. Associated with each fluid therapy session, dogs received renal sonograms with renal pelvis mensuration at hours: -24, -16, 4, 8, and 24, with fluids commencing at 0 hr. Ultrasound examinations were performed using a 12-5 MHz linear array transducer by observer CL at which time measurements were obtained. Standardized measurement criteria were established prior to the study: A, B in the transverse plane and D, E in the dorsal plane. Observer PF made measurements on still images obtained by CL. The authors were blinded to what fluid rates were administered. Results: No significant differences were observed between renal pelvis measurements at the fluid rates and dog weights evaluated. Significant differences were observed in some renal pelvis measurements between baseline and fluid administration. These differences were seen at the end of fluid administration (8hrs), except for measurement E (dorsal plane; across ureter at junction of ureter and pelvis) which was also different from baseline at 4hrs. Reference values for each measurement were calculated for baseline and for each subsequent time period. The measurements 16 hours after discontinuing fluid administration were not significantly different from baseline. Observer PF consistently had significantly larger measurements than CL. Significant differences between renal pelvis measurements were seen between kidneys of the same dog in two dogs during some of the fluid therapy sessions. Discussion/Conclusions: Therapeutically utilized intravenous fluid rates cause secondary renal pyelectasia, most notably after 8 hours. This dilation resolves after discontinuation of fluids for 16 hours. Measurement E maybe more sensitive for detection of pyelectasia. The rate of fluid administration does not affect degree of pyelectasia, at the fluid rates used in this study.

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THE EFFECT OF MITRAL VALVE REGURGITATION IN DOGS ON THE LEFT VENTRICULAR SEPTUM. P.F. Lord, A. Todosijevic, M.K. Hansson, J. Häggström. Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden. Introduction/Purpose: The effects of chronic mitral valve due to myxomatous mitral valve degeneration on the right ventricle (RV) are not established. The cranial and right heart borders on radiographs appear to become enlarged and convex with increasing severity of MR. Recent reports of pulmonary hypertension (PH) in association with MR suggest a mechanism for right-sided enlargement in some dogs. Tricuspid valve regurgitation also may be present. RV pressure (PO) and volume overload (VO) cause the interventricular septum (IS) to become flattened at end systole (ES) and end diastole (ED) respectively due to changed transseptal pressure gradients. This study aimed to determine if the septum became flattened and the right side more convex in dogs with MR as the heart enlarged. Methods: Tape-recorded echocardiograms made on 42 cavalier king Charles spaniels with varying degrees of MR were reviewed and short segments digitized for analysis. 3 LV short axis frames at ED and 3 at ES were saved and printed. The radius of curvatures of the endocardium of the IS and left ventricular free wall (FW) were measured and averaged, and the ED and ES IS/FW and IS/FW calculated and related to ratios of cranial and R heart border curvature on radiographs and to an index of heart size (vertebral heart scale, VHS). VHS was split into 3 groups, mild enlargement =/< 11.6, normal and mild enlargement; 11.6-13.5, moderate enlargement, and =/> 13.5, severe enlargement. The bulge of the right (VD view) and cranial (left lateral view) heart borders on radiographs related to heart length was measured. Results. There was no relationship beween curvature indexes and septal flattening. ED IS/FW did not change with increasing heart size, but ES IS/FW of hearts with severe enlargement was significantly greater than that of hearts with no-moderate enlagerment. The degree of SF however, compared with studies on human patients, indicated significant pulmonary hypertension in only 2 dogs. In the lateral view relative cranial heart curvature decreased in moderately enlarged hearts and in the VD view increased in severely enlarged hearts. Discussion/Conclusions: Increasing VO is not a cause of apparent right-sided heart enlargement, whereas increased SF at ES in some dogs with severe heart enlargement indicated PO in some dogs only. The absence of SF proportionate to the size of the heart and curvature suggests that right sided heart enlargement is not a consistent feature of MR and does not cause the convexity. Only in the VD view of severely enlarged hearts is the right sided curvature disproportionately increased.

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DIFFERENTIATION OF PRIMARY FROM METASTATIC HEPATIC NODULES IN DOGS

USING CONTRAST-ENHANCED HARMONIC ULTRASOUND. C.R. Oliveira, N. Rademacher, L. Gaschen. From the Section of Diagnostic Imaging, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803. Introduction/Purpose: Contrast-enhanced harmonic ultrasound (CEHUS) has been shown to be accurate for differentiating benign from malignant liver nodules in dogs.1 However, little attention has been paid to enhancement quantification and angioarchitectural differences between primary and metastatic disease. Evaluation of the angioarchitecture with CEHUS improves sensitivity and accuracy for characterization of malignant hepatic lesions in humans2. The purpose of this study was to assess the angioarchitecture and pixel intensities between different types of malignant and benign hepatic nodules in dogs using CEHUS. Methods: Dogs presented for abdominal ultrasound were selected if at least one nodule was detected in the liver and biopsy and/or fine needle aspiration of the nodule for histopathology or cytology were performed. A second generation ultrasound contrast agent Definity® (Bristol-Myers Squibb, NB, MA) was administered intravenously and the vascular patterns of the nodules were evaluated using harmonic ultrasound from digitally recorded clips. Using Qlab® version 4.2.1 dedicated software (Philips, WA, USA), ROI’s were drawn within the nodule and adjacent parenchyma at 3 different times during portal enhancement (20-50 seconds post injection), and the mean dB/mm2 was recorded.3 T test analysis was performed to test for statistic differences between the groups. Results: 12 dogs were examined. Six dogs had malignant lesions which were all hypoechoic during the portal phase of perfusion and four different vascular patterns were identified: intralesional vessels, perilesional vessels (ring-enhancement), feeding vessels or a combination of 2 or more. Changes in angioarchitecture were not seen in benign lesions. Three primary tumors (hepatocellular carcinomas) had a statistically significant difference in pixel intensity compared with metastatic (p<0.009) and benign (p<0.029) lesions. Two metastatic tumors (insulinoma, histiocytic sarcoma) exhibited early ring enhancement in the arterial phase that differed from that of primary neoplastic lesions. Five benign lesions were diagnosed (cholestasis, neutrophilic inflammation and steroid hepatopathy), all demonstrating patterns of enhancement different from malignant nodules: isoechoic to the surrounding liver during the late portal phase and no evidence of lesional vessels. One necrotic lesion appeared hypoechoic during the late portal phase with peri-lesional vessels throughout the arterial and portal phases. Discussion/Conclusions: Assessment of the angioarchitecture and enhancement quantification of hepatic nodules with CEHUS may be a useful tool for differentiating primary versus metastatic disease in dogs. Necrosis is a differential diagnosis for nodules demonstrating malignant CEHUS patterns. Pitfalls of this study included small number of cases and presence of only cytology as the final diagnosis for 5 dogs and a larger population should be assessed to confirm the conclusions of this study. References: 1. O'Brien RT, Iani M, Matheson J, Delaney F, Young K. Contrast Harmonic Ultrasound of Spontaneous Liver Nodules in 32 Dogs. Veterinary Radiology & Ultrasound 2004;45(6):547-553. 2. Rettenbacher T. Focal liver lesions: Role of contrast-enhanced ultrasound. European Journal of Radiology 2007;64(2):173-182.

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ULTRASOUND IMAGING OF THE INGUINAL REGION OF ADULT MALE LOGGERHEAD

SEA TURTLES (CARETTA CARETTA). A. Pease, G. Blanvillian, D. Rostal, D. Owens, A. Segars.

Introduction/Purpose: The biology and reproductive anatomy of male loggerhead sea turtles (Caretta caretta) has been difficult to study. To date, the principle method for evaluation of the coelomic cavity in both adult and juvenile male sea turtles is celioscopy. Ultrasound evaluation has been mainly limited to the reproductive structures of adult females for the identification and measurement of follicles and eggs. No studies that evaluate the reproductive anatomy of adult male sea turtles have been previously performed. The purpose of this study was to describe the technique and structures visualized when scanning the inguinal region of live, wild-caught, adult male loggerhead sea turtles, and compare it to celioscopy and necropsy findings.

Methods:

Twenty-one adult male loggerhead sea turtles were collected by trawling in the Cape Canaveral shipping channel in April 2007. All turtles were placed in dorsal recumbency and imaged with a Sonosite 180 Vet Plus (Sonosite, Inc. Bothell WA) and a microconvex, 4-7 MHz curvilinear array probe. The inguinal region was divided into four quadrants: cranial, lateral, medial, and caudal. Celioscopy was performed on 13 turtles and biopsies were obtained of the testes and the epididymides to confirm correct identification of the structures. In addition, the caudal half of one adult loggerhead was found during trawling and identification of the kidneys was confirmed on gross inspection, and ultrasound in a water bath.

Results: The sea turtles collected had an average straight carapace length (notch to notch) of 93.0 cm ± 6.7 cm (range: 81.1 cm – 107 cm) and an average weight of 116.8 kg ± 26.0 kg (range: 81.0 kg – 172.5 kg). In the cranial aspect of the inguinal region, the urinary bladder, large and small intestines were identified. Five distinct layers of the intestine were seen, similar to ultrasound images of small animals. The bowel was generally fluid distended with contractility identified within the presumed small intestine. In the lateral inguinal region, the lung and kidney were seen. The kidney was present in the retrocoelomic cavity and identified separately from the testis and gastrointestinal tract. No adrenal glands were identified. In the medial aspect of the inguinal region, the testis and epididymis were routinely identified. In the caudal aspect of the inguinal region, the coxofemoral joint was visualized. Biopsy results of the testes and epididymides confirmed correct ultrasonographic identification.

Discussion/Conclusions:

The ultrasonographic appearance of the organs of the adult male loggerhead sea turtle was similar to that in other species. The adult loggerhead sea turtles that were imaged had a large acoustic window present in the inguinal region. This allowed for a large amount of probe movement and rotation to acquire the optimum image. A small learning curve was required; however, correlation with celioscopy and biopsy showed that consistent, repeatable identification of caudal coelomic structures was easily achieved. Ultrasound provided an inexpensive, rapid, non-invasive method to evaluate the reproductive anatomy of live-captured, male loggerhead sea turtles.

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COMPARISON OF RADIOGRAPHY AND ULTRASONOGRAPHY TO DETECT

OSTEOCHONDROSIS LESIONS IN THE EQUINE TARSOCRURAL JOINT. F. Relave, M. Meulyzer, K. Alexander, G. Beauchamp, M. Marcoux. Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.

Introduction/Purpose: Osteochondrosis (OC) lesions of the equine tarsocrural (TC) joint are routinely diagnosed using radiography, but lesions on the medial malleolus (MM) can be difficult to image and may require the dorso30°lateral-plantaromedial oblique (D30°LPMO) view. Ultrasonography allows evaluation of cartilage and subchondral bone in the TC joint and is potentially useful in diagnosing OC lesions.

Methods: Horses admitted for arthroscopic removal of OC lesions in one or both TC joints were included. Joints with OC lesions were evaluated prior to arthroscopy by radiographic (dorsoplantar, lateromedial, D45°LPMO, D45°MPLO and D30°LPMO views) and ultrasonographic (longitudinal and transverse scans of the dorsal aspect of the joint) examinations. Modalities were compared with arthroscopy as the gold standard. Interobserver agreement was determined for each modality using kappa statistics.

Results: One hundred and eleven joints were included. Arthroscopically, subchondral bone and/or cartilage lesions on the MM, distal intermediate ridge (DIR) and lateral trochlear ridge (LTR) were detected in 32, 99 and 5 joints respectively. The sensitivity of radiography for subchondral bone lesions on the MM and DIR was 71% and 96%, and specificity was 83% and 71%. Ninety-four percent of lesions on the MM were better detected on the D30°LPMO view. The sensitivity of ultrasonography to detect subchondral bone lesions on the MM and DIR was 83% and 99%, and specificity was 96% and 60%. Ultrasound could detect 50% of cartilage lesions. Ultrasonography was significantly more sensitive than radiography to detect lesions on the MM (p=0.02) and DIR (p=0.049). Specificity was not significantly different between radiography and ultrasonography for either site (MM p=0.10, DIR p=0.48). For radiography, agreement between observers ranged from 0.58 to 1 depending on the site, with the highest disagreement for lesions on the MM. For ultrasonography, agreement between observers for subchondral bone lesions was 0.80-0.96. Discussion/Conclusions: Ultrasonography was a useful diagnostic tool for OC lesions in the TC joint and compared to radiography, was more sensitive for subchondral bone lesions located on the MM and DIR (slightly), and had a higher interobserver agreement. This modality should be considered by experienced operators as an adjunct to radiographic examination. The D30°LPMO was the best view to image lesions on the MM and should be included in radiographic examination of the equine tarsus for the detection of OC.

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COMPARISON OF CONVENTIONAL MYELOGRAPHY AND POST-MYELOGRAPHY COMPUTED TOMOGRAPHY FOR THE EVALUATION OF CANINE COMPRESSIVE MYELOPATHY. K.J. Childs, W.T. Drost, V.F. Samii, L. Nelson. The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210. Introduction/Purpose: CT myelography in humans correlates well with conventional myelography findings in the lumbar and cervical spine, in many cases, adding specific information unavailable from conventional myelography. A specific example where post-myelography CT is useful is the differentiation of osteophytes from disk herniation in the cervical spine. Other studies show that conventional myelography and CT myelography are equally useful with no surgically or clinically added benefit provided by CT. In dogs, CT myelography provided added information on the exact location and degree of spinal cord compression due to cervical spondylotic myelopathy and better assessed the bony changes associated with extradural spinal tumors. However, it was suggested that conventional myelography more correctly classified spinal cord tumors than CT. We compared the findings and accuracy of conventional digital myelography and post-myelography CT in the diagnosis of compressive myelopathy to assess the usefulness of post-myelography CT. Methods: Fifty dogs with neurologic signs compatible with compressive myelopathy underwent digital conventional myelography using intrathecal iohexol followed immediately by post-myelography CT. Post-myelography CT was performed at sites identified by the attending radiologist and/or surgeon at the time of myelography. Case selection included studies with three or fewer compressive lesions located from C2-3 to L6-7. Studies were reviewed independently by two board certified radiologists and a board certified surgeon in random sequence without prior knowledge of signalment, clinical history, surgical findings, or results of other imaging studies. Images were assessed for site, type (extradural, intradural/extramedullary, intramedullary), and characterization of compression for lateralization and degree of severity. Results were compared to surgical findings when performed. Results: The myelography and post-myelography CT diagnosis of site of compressive myelopathy agreed with surgical findings 74.3% and 82.9%, respectively, at sites with complete observer agreement. For lesion type, myelography and CT agreed with surgery 74.3% and 77.1%, respectively. The agreement for site and lesion type increased to 88.6% for myelography and 94.2% for post-myelography CT if including cases where 2/3 observers agreed. Determination of laterality for myelography and post-myelography CT matched surgical findings 62.9% and 71.4%, respectively. For non-surgical cases, myelography and post-myelography CT agreed for 3/3 observers in 13.6% of cases on site of lesion and 50.0% on lesion type. Agreement increased to 54.5% and 77.3% respectively if 2/3 observer agreement was considered. All non-surgical cases had lesions rated moderate or less in severity. Discussion/Conclusions: Myelography and post-myelography CT findings generally agreed as to site and type of compressive lesion. When myelography and CT did not agree, CT identified additional compressive lesions or indicated lack of spinal cord compression at sites identified on myelography. This occurred most often in cases of cervical compressive myelopathy with multiple sites. Laterality disagreement was usually due to failure of one observer to detect any laterality of a given lesion. CT changed the diagnosed lesion laterality in 5/35 surgical cases but did not change surgical approach in any case. Cases with poor interobserver agreement were limited to the second of two compressive lesions in the same study with good agreement at the most compressive site. Post-myelography CT is useful in further characterizing compressive lesions for surgical planning, especially in cases of cervical spondylotic myelopathy; however, diagnosis of site and type of compressive myelopathy is generally not changed by its use.

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QUALITY OF EXCRETORY UROGRAPHY UISING A LOW DOSE OF IOHEXOL: A PILOT STUDY. F. H. David, R. B. Page. Ross University School of Veterinary Medicine, St Kitts, West Indies. Introduction/Purpose: The recommended dose of iodinated contrast product for excretory urography (EU) in dogs is 880 mg of I/kg. This dose was determined using sodium iothalamate which is an ionic iodinated contrast media with high osmolality. In humans, several studies have shown that non-ionic iodinated contrast media with low osmolality, such as Iohexol, can achieve excellent quality EU, when used with a dose of Iodine lower than those recommended for ionic iodinated contrast media. The purpose of this study was to compare the quality of opacification of the upper urinary tract using the three different doses of Iohexol. Methods: Six adult mixed breed female dogs were administered iohexol on 3 separate occasions at different doses (300, 600 and 880 mgI/kg). Dogs were only sedated with butorphanol in order not to affect GFR. Abdominal radiographs were obtained before injection and every five minutes for forty minutes after injection. The contrast studies were blindly and independently evaluated by two readers for quality of the excretory urography. Opacification of the nephrogram, pelvis, pelvic recesses and ureters were given scores from 0 to 2, based on no, partial, or complete detection of these structures. A score from 0 to 3 was given for the overall quality of the contrast study. The effect of doses on opacification of the different structures and overall quality were tested for the influence of dose using a Friedman test. Results: No significant difference between the three concentrations of Iohexol was obtained for any of the evaluated structures neither for the overall quality of the excretory urography. Discussion/Conclusions: These results suggest that the quality of detection of the different structures of the upper urinary tract during EU in normal dogs is not different using a dose of 300, 600 or 880 mgI/kg. EU using iohexol can be performed with a dose of 300 mgI/kg. This dose is also the one routinely used for glomerular filtration rate (GFR) determination using iohexol blood clearance. Both EU and GFR determination could be performed with one single injection of iohexol, enabling to reduce costs for the owners, and risks and stress for the animals. Further evaluation in clinical cases with decreased renal function is necessary in order to determine if the quality of EU using a low or high dose of iohexol is not different.

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RADIOGRAPHIC IMAGING OF THE EQUINE TEMPOROMANDIBULAR JOINT. A. J. Ebling, A. McKnight, G. Seiler, P. Kircher. Department of Diagnostic Imaging, Vetsuisse Faculty of Zürich, University of Zürich, 8957 Zürich, Switzerland. Introduction/Purpose: The complexity of the equine skull and superimposition of cranial structures make the temporomandibular joint (TMJ) a difficult area to evaluate on plain film. The objectives of this study were to evaluate the anatomic features of the TMJ of horses of different breeds and ages based on computed tomographic three dimensional (3D) reconstruction and to develop a complementary diagnostic radiographic projection of the equine TMJ. Methods: Computer tomography (CT) was performed on 6 heads of horses that were euthanized for other reasons than TMJ disease. After 3D reconstruction of the equine head, the skull was placed in a lateral position so that the ventral border of the body of the mandible was parallel to the horizontal surface. A line was drawn through the cranial aspect of the TMJ and the angle between this line and a horizontal line was measured. The results showed that the described angle of the TMJ measured approximately 45-degrees in all the cadaver heads. Based on these measurements a radiographic projection of the TMJ in a rostral 45-degrees ventral-caudodorsal oblique direction was developed and applied on the same cadaver heads. For the radiographic projection the horse heads were placed on a table so that the ventral border of the mandible was parallel to the ground and the X-ray beam was centered on the TMJ. Four additional views were obtained by moving the X-ray unit laterally by 10-, 20-, 30- and 40-degrees. The rostral 45-degrees ventral-caudodorsal oblique angle and the beam being centered on the TMJ remained as previously described. All radiographic views were applied on both TMJs of the 6 equine cadaver heads as well as on one live horse. Results: The rostral 45-degrees ventral-caudodorsal oblique projection revealed clear identification of the TMJ space and mandibular condyle in all the horses. A superior diagnostic radiographic projection was obtained by having the X-ray unit angled 30-degrees laterally in addition to the rostral 45-degrees ventral-caudodorsal oblique angle. This additional lateral angle resulted in decreasing superimposition of the os zygomaticum, os temporale and the coronoid process of the mandible with the axial aspect of the TMJ and provided better visualization of the TMJ space and the mandibular condyle. Discussion/Conclusions: We conclude that there is a rostrocaudal projection of the TMJ, which allows superior visualization of the TMJ space and the mandibular condyle in horses. Not only the rostral 45-degrees ventral-caudodorsal oblique angle of the X-ray unit, also the horizontal positioning of the body of the mandible are important in order to obtain the described projection of the TMJ. The developed radiographic view can be applied on horses of different ages and breeds and will be helpful in the future to diagnose disorders associates with the TMJ.

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MYELOGRAPHY VS. COMPUTED TOMOGRAPHY IN THE EVALUATION OF ACUTE INTERVERTEBRAL DISC EXTRUSION IN CHONDRODYSTROPHIC DOGS. S. Hecht, W.B. Thomas, K. Marioni-Henry, R.L. Echandi, A.R. Matthews, W.H. Adams. University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996. Introduction/Purpose: Acute thoracolumbar intervertebral disc extrusion is common in chondrodystropic dogs and requires accurate identification of the site of spinal cord compression prior to surgery. Myelography is the most commonly performed imaging procedure for the diagnosis of intervertebral disc herniation in small animals. It is fast and fairly accurate; however, adverse reactions to contrast material may occur. Many consider computed tomography (CT) to be more accurate in the assessment of compressive spinal cord disorders in human patients, and CT is helpful in identifying extruded disc material in dogs. The advantage of helical over conventional (axial) CT is a marked decrease in examination time, which is partially offset by a reduction in exposure dose and image quality. The purpose of this study was to determine accuracy of myelography, conventional and helical CT and evaluate interobserver agreement in the diagnosis of acute intervertebral disc extrusion. Methods: 20 chondrodystrophic dogs referred for signs compatible with acute thoracolumbar intervertebral disc extrusion underwent conventional CT, helical CT and myelography prior to hemilaminectomy. All studies were randomized and independently evaluated by 2 board certified neurologists and 3 board certified radiologists blinded to clinical and surgical findings. Imaging findings were compared to surgical findings, which were considered the gold standard for the purpose of this study. ANOVA and Kruskal-Wallis ANOVA on ranks were used to compare imaging findings of individual investigators to surgical findings. Kappa statistics were applied to determine interobserver agreement. A P-value of < 0.05 was considered significant. Results: One dog had to be excluded from evaluation due to multiple compressive lesions and inability to determine exact site and number of extruded discs. In the diagnosis of level of disc extrusion there was agreement between myelography, conventional CT and helical CT with surgical findings in 94.7%, 100% and 94.7%, respectively (P = 0.144). In the diagnosis of level and lateralization of disc extrusion there was agreement between myelography, conventional CT and helical CT with surgical findings in 78.9%, 87.4% and 85.3%, respectively (P = 0.328). Interobserver agreement was very good for all imaging modalities (Myelography kappa 0.87; conventional CT kappa 0.86; helical CT kappa 0.95). Discussion/Conclusions: No significant differences were found between myelography, conventional and helical CT in the evaluation of acute intervertebral disc extrusion in chondrodystrophic dogs.

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COMPARISON OF ULTRASOUND-GUIDED TRANS-SPLENIC PORTOGRAPHY WITH

TRANS-SPLENIC PORTAL SCINTIGRAPHY IN NORMAL DOGS. V.L. Heffelman, E.K. Randall, B. Stanley, M. Fritz, J Kinns, J. Hauptman. Michigan State University College of Veterinary Medicine, East Lansing, MI, 48864.

Introduction/Purpose: Congenital portosystemic shunting (PSS) is seen commonly in canine veterinary patients. An accurate anatomic diagnosis will affect prognosis and determine the attenuation technique (i.e., abdominal surgery or interventional radiology). Several diagnostic techniques are available, including ultrasonography, various fluoroscopic angiography studies, per-rectal or trans-splenic scintigraphy, and CT or MRI angiography, but there are significant limitations which each method. The purpose of this study is to establish a method for ultrasound-guided trans-splenic portography in our institution and to compare the quality of ultrasound-guided trans-splenic portography (TSPG) to ultrasound-guided trans-splenic portal scintigraphy (TSPS) for evaluation of normal portal circulation in 6 dogs. Methods for both tests have been previously described. This study will provide a basis for comparison of both exams in an ongoing study in clinical patients with extrahepatic portosystemic shunts. Since not all institutions have access to scintigraphy and/or fluoroscopy, we aim to show that either test may be confidently utilized as a diagnostic tool for patients with suspected portosystemic shunts.

Methods: Six normal, young Beagle dogs considered healthy by bloodwork (including normal bile acids), urinalysis, abdominal radiographs, and abdominal ultrasound were evaluated. Ultrasound-guided TSPG and TSPS were performed in each dog in random order 1-2 days apart from each other. An ordinal grading scale, developed from the authors’ thoughts and discussions on scales and knowledge of the tests themselves, was utilized to grade the tests in their ability to accurately visualize levels and location of portal blood flow. One blinded board-certified radiologist reviewed the randomized exams two times to evaluate for intraobserver variability. Results: The Kappa agreement statistic to assess agreement between the two observations was 100% for portal scintigraphy, as compared to 71% for portography. The median score for scintigraphy (4.0) was lower than for portography (6.25). The Wilcoxon signed-rank test for the difference in the medians was 0.026, indicating a significant increase in the ability to visualize portal vasculature via portography. The amount of contrast medium needed for portography was greater than the amount of radiopharmaceutical needed for scintigraphy. The larger portography dose did lead to occasional peritoneal injections (4/6 dogs) that did not impede study interpretation or minor splenic edema/hemorrhage that completed dissipated 1-2 hours post-study in 2 dogs. Portal streamlining to the right side was noted in all dogs during portography.

Discussion/Conclusions: Portography provides more detailed information regarding branching of the portal system in normal dogs, which should allow better surgical planning for dogs affected with portosystemic shunts. This conclusion will be further evaluated in the clinical portion of the study that is currently underway. However, portography requires a larger injection of material into the splenic parenchyma, leading to a higher, but clinically insignificant, rate of complications and consistent portal streamlining.

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SERIAL POSTMORTEM THORACIC RADIOGRAPHIC FINDINGS IN CANINE CADAVERS. 1Hock Gan Heng, 2Gayathri Thevi, 2Hiang Tee Lim, 2Jin Seng Ong, 2Jie Han Lim, 2Jin Tatt Ooi. 1Department of Veterinary Clinical Sciences, Purdue University, 625, Harrison Street, West Lafayette, IN 47907 2Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia. Introduction/Purpose: Post mortem radiographic examinations of animals are often performed in judicial investigation to rule out gunshot and fractures due to cruelty. Literatures describing animal radiographic postmortem changes are rarely available.1,2 Methods: Serial lateral and ventrodorsal thoracic radiographs of 6 recently euthanized dogs were performed in intervals of 8 hours at a tropical ambient temperature of 22 to 33ºC. All six had radiographs at 16 hours post-euthanasia and only 3 had radiographs at 24 hours post-euthanasia. Radiographic changes such as presence of gas and/or fluid in the pleural cavity, cranial mediastinum, blood vessels and cardiac chambers were observed. The size of the cardiac silhouette was estimated by using the vertebra heart sum method. Changes of the lungs such as alveolar, interstitial, bronchial and vascular patterns and extrathoracic structures were noted. Results: Gas gradually developed in the pleural cavity, mediastinum, blood vessels and cardiac chambers of all cadavers. Lungs developed alveolar pattern and subsequently collapsed secondary to severe pneumothorax. Vacuum phenomenon of the scapulohumeral joints was detected in 2 cadavers. Most radiographic changes were detected at 16 hours post-euthanasia. Severe subcutaneous emphysema developed between 16 and 24 hours post-euthanasia. There was no statistical difference of the size of the cardiac chambers. Discussion/Conclusions: This study shows that gradual gas production and accumulation in the pleural cavity, mediastinum, blood vessels, cardiac chambers, scapulohumeral joints and subcutaneous emphysema is a consequence of putrefaction. Vacuum phenomenon of the joints has not been reported in human cadavers. Interpretation of postmortem radiographs should be taken into consideration of the normal postmortem changes as described in this study. References. Heng HG, Teoh WT, Sheikh-Omar AR. Postmortem abdominal radiographic findings in feline cadavers. Vet Radiol Ultrasound 2008;49:26-9. Ober CP, Spotswood TC, Hancock R. Fatal venous air embolism in a cat with retropharygeal diverticulum. Vet Radiol Ultrasound 2006;47:153-8.

36

CAN IMAGE PROCESSING IN DIGITAL RADIOGRAPHY COMPENSATE FOR THE USE OF

AN ANTI-SCATTER GRID?* W.Y. Lo1, W.J. Hornof2, I.D. Robertson3. 1University of California, Davis, CA, 95616, 2Eklin Medical Systems, Inc., CA, 95054, and 3North Carolina State University, NC, 27606. Introduction/Purpose: Traditionally anti-scatter grids are used with patients thicker than 10-13 cm to reduce the amount of scatter radiation. It is well accepted that the distribution of scatter radiation is of low spatial frequency while useful patient anatomy is of higher frequency. Modern imaging processing algorithms allow manipulation of the frequency domain components of the image. The purpose of this study was to subjectively determine if frequency domain image processing of digital radiographs could reduce the need for an anti-scatter grid in veterinary patients larger than the accepted 10-13cm limit.

Methods:

Orthogonal thoracic and abdominal radiographs of 5 variably-sized, clinically healthy dogs (12cm to 27cm patient thickness) were obtained using a commercially available digital radiography system (Eklin EDR6). Four images were generated for each projection: group 1: acquired with a fixed grid and application of a frequency-domain algorithm (Canon MLT(M)), group 2: acquired with a grid at the same technique as (1) but with no image processing algorithm other than adjustment of a sigmoid-shaped look-up-table such that the final image mimicked a traditional screen-film radiograph (pseudofilm), group 3: acquired without a grid at the same technique as the previous and application of the same frequency-domain algorithm, and group 4: acquired without a grid but at half the mAs as the previous and application of the same algorithm. The images taken without a grid (groups 3 and 4) were iteratively processed to match the images acquired using a grid and image processing (group 1). Six ACVR diplomates independently reviewed the radiographs and scored the images using a 5-point scale for overall diagnostic quality. The observers also reviewed and scored magnified images for the ability to accurately assess specific anatomic structures within the thorax and abdomen. Non-parametric statistical analysis was performed to compare the mean scores.

Results:

Results showed that all the thoracic and abdominal radiographs were of acceptable to excellent diagnostic quality. On overall diagnostic quality, most reviewers preferred the digitally processed radiographs over the mimicked screen-film radiograph regardless of patient size, presence of a grid, or exposure technique. For the magnified images, there was no statistical difference in the reviewers’ ability to accurately assess specific anatomic structures between the non-grid (groups 3 and 4) and with-grid images (groups 1 and 2). In addition, the digitally processed images (regardless of a presence of a grid or exposure dose) generally scored better than the pseudofilm images.


This preliminary study suggests that frequency-domain image processing of digital radiographs can compensate for an anti-scatter grid in patients as large as 27cm in thickness. Elimination of the grid can reduce the probability of technical errors and potentially lead to decreased exposure. Further quantitative studies are needed to better characterize the ability of frequency-domain image processing to negate the need for a scatter removing grid in small animal radiography. *Funded in part by an ACVR Resident Research Grant

37

COMPUTED TOMOGRAPHIC FEATURES OF RESPIRATORY ANATOMY AND PATHOLOGY OF THE WHOOPING CRANE (GRUS AMERICANA). Schwarz T1, Pinkerton ME2, Kelley C3, Hartup BK1,3 School of Veterinary Medicine, Departments of 1Surgical and 2Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, and 3International Crane Foundation (ICF), Baraboo, WI 53913. Introduction/Methods: The whooping crane is a migratory North American bird for which intense preservation efforts are made including re-establishment of migratory patterns. Between 2003 and 2007, 6 juvenile cranes housed at the ICF with signs of respiratory illness underwent a respiratory CT examination under general anesthesia. Retrospectively, the technical CT parameters were recorded; tracheal, bronchial, pulmonary and airsac anatomy was identified and any respiratory and other abnormalities noted and compared to necropsy findings. Results: A variety of CT parameters were used (slice width 1–5 mm, axial or helical [4/2 cases] acquisition mode, scan duration 35 sec to 10 min). Respiratory anatomic imaging features included a dual-coiled intrasternal tracheal segment, a syrinx with two emanating bottle-shaped primary bronchi, and secondary bronchi connecting lungs with airsacs. Abdominal, cervical, clavicular and both thoracic airsacs were identified as well as humeral, sternal, scapular, coracoid, axillary and pelvic diverticuli. Identified pathology included occlusion of the bottleneck portion the primary bronchus (5 cases), lung and secondary bronchi (3 cases); airsac masses & thickening (2 cases); and traumatic rib/clavicular fracture with subcutaneous emphysema (2 cases). Owing to the poor prognosis all six birds were euthanized and necropsy was performed. Necropsy, histology and culture findings closely matched CT findings and revealed fungal granulomatosis in all 6 birds (Aspergillus fumigatus or sp.). Discussion/Conclusions: CT enables unique insights into respiratory anatomy and pathology of whooping cranes in a very fast, efficient, detailed and comprehensive way. CT allowed correct identification of currently untreatable airway obstruction.

38

DEVELOPMENT OF DIGITAL MULTIMEDIA RADIOLOGY TEACHING FILES. R. Tyson. Virginia-Maryland Regional College of Veterinary Medicine. Blacksburg, VA 24061. Introduction/Purpose: With the growing popularity of digital radiography and other digital imaging modalities, the development of digital radiology teaching files is a natural evolution. Traditional radiology teaching files have consisted of a hard copy film study accompanied with a radiographic description or report. Students with little applied radiology experience often have great difficulty learning with this type of teaching method without assistance. The Radiological Society of North America (RSNA) Radiology Informatics Committee initiated a project to construct an internet accessible, globally cooperative, digital radiology teaching file library called Medical Imaging Resource Center (MIRC). MIRC is an open-source project that has been modified for veterinary use, as previously reported1. MIRC is customizable and is able to present cases in a stepwise manner. In an attempt to better aid student comprehension and learning, screen capture software was utilized to develop multimedia radiology teaching file cases that can be incorporated into MIRC. The screen capture software enabled simultaneous full motion screen capture, annotation of images, audio recording and the ability to have interactive features. Methods: Screen capture software was installed on computers with DICOM viewers and a multimedia computer workstation with interactive pen display. All computers had the ability to record audio and used a variety of microphone recorders. Using an internet browser, the case was authored in MIRC and the multimedia screen capture file was attached to the case. Once published within MIRC, the case is accessible via the internet. Results: Students overwhelmingly preferred the multimedia teaching files compared to traditional methods. Subjectively, student understanding of the material presented and applied radiology skills were similar to that of students with similar rounds discussions. The multimedia teaching files appear to be subjectively superior at developing applied radiology skills in students when compared to traditional teaching file methods. Discussion/Conclusions: Screen capture software is an efficient method for producing multimedia radiology teaching files that subjectively enhance student learning and applied radiology skills. Using screen capture software with MIRC creates a very powerful teaching archive that is accessible via the internet, has extensive search capabilities, is modified for veterinary use and encourages viewing of cases in a realistic stepwise manner. Future integration with physical exam and pathology media will aid cross discipline integration. References 1. Zwingenberger AL, Ward PR. Medical Imaging Resource Center (MIRC) for veterinary medicine: a digital imaging teaching file. J Vet Med Educ 2006 33(4):618-21.

39

THE EFFECT OF MANUAL INFLATION VERSUS SPONTANEOUS INSPIRATION ON THE CARDIAC SILHOUETTE IN DOGS. N. Webster, V. Adams and R. Dennis. Animal Health Trust, Newmarket, UK. CB87UU. Introduction/ Purpose: When radiographing the thorax of an anaesthetised patient, positive pressure inflation of the lungs is recommended but the effect of this on the appearance of the heart is not known. The purpose of this study was to assess radiographic heart size in anaesthetised dogs, comparing spontaneously-breathing inspiratory radiographs with those obtained using manual lung inflation. The hypothesis for this study was that manual inflation of the film would cause reduction in the cardiac size. Methods: A prospective study of dogs presenting for thoracic radiographs under general anaesthesia between 31/10/06 and 30/11/07 was performed. Patients were positioned in right lateral recumbency, a radiograph was taken at peak spontaneous inspiration and immediately afterwards a radiograph was taken during application of positive pressure manual inflation. The radiographs were interpreted by two blinded observers assessing cardiac size, both subjectively, (using a numerical grading scheme whereby 1 = small, 2 = normal, 3 = equivocally enlarged, 4 = enlarged) and objectively, using the vertebral heart scale method (VHS). Seven patients also had conscious thoracic radiographs taken. These were included in the analysis with the observers aware that the patients were conscious. Results: 207 dogs were included in the study. In 71% of dogs the heart was smaller on the manually-inflated radiograph. For the subjective assessment, heart size was smaller on the inflated radiographs by a mean value of 0.2 of a grade (r=0.5, P<0.0001). For the objective assessment, the mean VHS score was smaller on the inflated radiographs by 0.24 vertebral length (range -1.2 to +1.2; SD 0.37; r=0.9; P<0.0001). For the seven dogs for which conscious radiographs were also available the VHS score on radiographs obtained under anaesthesia, whether spontaneously breathing or with manual inflation, was significantly lower than when the dog was conscious (P=0.003). Discussion/Conclusions: This study shows that a statistically-significant reduction in the VHS score occurs with manual inflation of the lungs and in any individual patient the degree of difference with inflation may be up to 1.2. Based on a limited number of dogs the heart may also be smaller when the patient is anaesthetised compared with the conscious state. Thus cardiomegaly may be missed or underestimated in anaesthetised dogs especially in manually-inflated radiographs, and if serial radiographs are being taken to monitor a patient’s heart size the radiographic technique should be consistent.

40


Thursday, October 23, 2008 7:15 am Nuclear Medicine Society Business Meeting – Drost 8:00 am Scientific Session 3: Nuclear Medicine Moderator: Drost 8:00 am The Use of Hepatobiliary Scintigraphy to Assess Acute Liver Injury from

Aflatoxicosis in White Carneau Pigeons – Daniel 8:12 am Diuretic Renal Scintigraphy in Normal Cats – Hecht 8:24 am Diuretic Renal Scintigraphy in Cats With Urolithiasis – Lawson 8:36 am Normal Thoracic and Abdominal Distribution of 2-Deoxy-2-[18F] Fluoro- D-

Glucose (18FDG) with Positron Emission Tomography in Adult Cats – Morandi

8:48 am Scintigraphic Features of Multiple Acquired Portosystemic Shunts Using

Transsplenic Portal Scintigraphy – Morandi 9:00 am The Effect of Iodinated Contrast Medium Administration on Thyroid

Scintigraphy in Normal Cats – Lee 9:30 am Break With Exhibitors 10:30 am Nuclear Medicine – Focus on Portosystemic Shunts – Drost 12:00 pm Lunch 1:30 pm ACVR Film Interpretation Session – Hornof 3:00 pm Break with Exhibitors 3:20 pm Resident Authored Paper and Grant Awards - Drost 3:30 pm Confirmation and Recognition of New ACVR Diplomates – Drost / Poteet 4:30 pm ACVR Business Meeting (Diplomates Only) – Pechman 6:30 pm Adjourn for the day

41

THE USE OF HEPATOBILIARY SCINTIGRAPHY TO ASSESS ACUTE LIVER INJURY FROM

AFLATOXICOSIS IN WHITE CARNEAU PIGEONS. G.B. Daniel1, TL Hadley2, DS Rotstein2, MP Jones2, J Grizzle3 1 Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061. 2College of Veterinary Medicine, 3Dept of Animal Science, University of Tennessee, Knoxville, TN 37996. Introduction/Purpose: Hepatobiliary scintigraphy has been used to quantify hepatic function in man, dog, horse and bird. Scintigraphic indices of liver function include HEF, time to peak liver uptake, biliary excretion rates, and blood pool clearances defined by AUC. The main purpose of this research was to evaluate the protective effect of Milk Thistle against acute aflatoxicosis in birds. A secondary purpose of this research and the main focus of this report was to evaluate hepatobiliary scintigraphy as a non-invasive alternative to histopathology to evaluate acute liver injury in birds.

Methods: Twenty-one healthy white carneau pigeons were divided into three groups. Anesthesia was induced and blood samples were obtained for hematologic and biochemical profiles. A bolus injection of 60 MBq of 99mTc-Mebrofenin was made into the basilic vein followed by a 40 minute dynamic acquisition. A liver biopsy was obtained via laparotomy. The liver samples were evaluated using a quantitative score representing the percent of tissue exhibiting degeneration, necrosis, inflammation or hemorrhage. The pigeons were then divided into three groups. The birds received 3 mg/kg of aflatoxin B1 suspended in DMSO. Group A received aflatoxin for 2 consecutive days, Group B for 3 days and Group C for 4 days. The day following aflatoxin administration, blood work and scintigraphy were repeated followed by euthanasia and necropsy

Results: After two days of aflatoxin administration all bird showed significant histopathologic changes in their liver accompanied by significant elevations in leakage enzymes. Functional tests such as bile acids and scintigraphic indices were elevated after 2 days but the differences were not significant until after 3 or 4 days of aflatoxin. Hepatobiliary indices continued to increase where as bile acids and the leakage enzymes peaked at 3 days of aflatoxin. There was good correlation between hepatobiliary indices and histopathogy.

Time To

Max

Liver Uptake

Half Time

Liver

Excretion

Fast

Phase

T 1/2

Slow

Phase

T 1/2

Area

under

Blood Pool

Curve

AS

T LDH Bile Acids

Histopat

hologic

Score

Baselin

e 2.8 8.4 0.74 17.93 5,340 169 319 3.7 0.7

Group A 4.5 114.8 1.21 25.88 9,841 931 3,175 46.8 6.0

Group B 8.0 184.6 2.87 68.67 20,488 879 4,359 89.8 5.5

Group C 10.3 174.5 4.00 86.20 24,351 671 3,713 67.7 5.5

Discussion/Conclusions: Scintigraphic parameters of liver function and bile acids were not as sensitive as leakage enzyme evaluation in detection of acute liver injury from aflatoxins. Unlike the other parameters, the scintigraphic parameters continued to increase with aflatoxin dose. Of the scintigraphic parameters, the area under the blood pool clearance curve had the highest correlation coefficient with histopathologic score.

42

DIURETIC RENAL SCINTIGRAPHY IN NORMAL CATS. S. Hecht1, I.F. Lane1, G.B. Daniel2, F.Morandi1, D.E. Sharp1. 1University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996. 2Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061. Introduction/Purpose: Diuretic renal scintigraphy, in which administration of a diuretic facilitates clearance of radiopharmaceutical from the renal collecting system, is used in humans to assess renal function and ureteral patency. The technique is applied to differentiate obstructive from non-obstructive hydroureteronephrosis, to predict surgical success after pyeloplasty, and to evaluate the potential for renal recovery from urinary tract obstruction in children.1 Diuretic renal scintigraphy has been assessed in normal dogs and dogs with urolithiasis.2,3 The purpose of this study was to describe diuretic renal scintigraphy findings in normal cats. Methods: Renal scintigraphy was performed twice in 10 healthy cats. Furosemide or saline were injected 4.5 minutes after administration of 103 ± 6.2 MBq (2.8 ± 0.2 mCi) 99mTc-DTPA for the diuretic and control scan, respectively. A dynamic acquisition was performed for 8 minutes, and time-activity-curves (TAC) were created applying regions of interest (ROI) to the dynamic data. Global and individual GFR, shape of the TAC, time of peak (TOP) of the TAC, T1/2 and percentage of maximum activity measured at end of study (8 minutes) were determined for each scan. Statistical evaluation was performed using Student´s t-test and Mann-Whitney Rank Sum test. Results: Global GFR in the control studies (2.79 ± 0.83 ml/min/kg, mean ± SD) did not differ significantly from the diuretic scans (2.34 ± 0.51 ml/min/kg). The shape of most (16/20) TAC of diuretic renograms was similar to those of control renograms. The TOP of the diuretic renogram curves was 3.06 ± 0.58 min, and did not differ from that of the control scans (3.01 ± 0.61 min). T1/2 of the diuretic renograms was significantly shorter (5.15 ± 0.83 min) than of the control renograms (6.31 ± 1.50 min). A significantly lower percentage of maximum activity was present at end of study in diuretic renograms (median: 47.25%; range: 33.60 – 59.60%) compared to control renograms (63.40%; 30.00 – 69.40%). Discussion/Conclusions: Diuretic renal scintigraphy is a rapid, easily performed and noninvasive procedure in cats. Unlike dogs and humans, the shape of diuretic renogram curves is similar to that of control renogram curves. References: 1. Conway JJ. "Well-tempered" diuresis renography: its historical development, physiological and technical pitfalls, and standardized technique protocol. Semin Nucl Med 1992;22:74-84. 2. Hecht S, Daniel GB, Lane IF. 99m-Tc-DTPA diuretic renography in dogs with urolithiasis. In: IVRA/ACVR Scientific Meeting, Vancouver, Canada 2006. 3. Hecht S, Daniel GB, Mitchell SK. Diuretic renal scintigraphy in normal dogs. Vet Rad Ultrasound 2006;47:602-608.

43

DIURETIC RENAL SCINTIGRAPHY IN CATS WITH UROLITHIASIS. S.M. Lawson1, S. Hecht1, I.F. Lane1, D.E. Sharp1, G.B. Daniel2. 1University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996. 2Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061. Introduction/Purpose: Diuretic renal scintigraphy has been described as a non-invasive technique in human patients to differentiate between obstructive and non-obstructive uropathy. Non-obstructed kidneys show a downward slope of the time-activity curve (TAC) after administration of furosemide. Obstructed kidneys show a continued rise of the TAC throughout the acquisition period. The purpose of this study was to evaluate the results of diuretic renography in cats with urolithiasis. Methods: Eighteen renal scintigraphy studies with administration of 3.0 mg/kg furosemide 4.5 minutes following injection of 112.4 ± 14.8 MBq (3.0 ± 0.4 mCi) of 99mTc-DTPA were performed in 15 cats with urolithiasis; therefore, 36 renogram curves were available for evaluation. Kidneys were subdivided into 5 groups based on scintigraphic, imaging and clinical findings (1 = non-obstructive urolithiasis, 2 = obstructive urolithiasis, 3 = severely decreased renal function, 4 = normal contralateral kidney if unilateral urolithiasis, 5 = equivocal for obstruction). Visual inspection of the TAC and calculation of excretion half time (T1/2) were performed for each kidney. Results: In group 1 (n = 6), all renograms showed a non-obstructive pattern with gradual and continuous downward slope of the curve following administration of furosemide. Median T1/2 was 6.09 (range 4.16 – 6.95) min. In group 2 (n = 8), seven curves showed continuous rise of the TAC, and one curve rose to peak and remained flat following peak activity. Median T1/2 was -7.91 (range -43.13 - +28.07) min. Time-activity curves for kidneys in group 3 (n = 17) remained flat throughout the examination, and T 1/2 was variable (Median 13.84; range 6.7 – 69.91 min). Kidneys with no evidence of urolithiasis (n = 4) had curves with a non-obstructive pattern. Median T 1/2 was 7.88 (range 6.19 – 9.17) min. In one kidney with equivocal evidence of obstruction (n = 1) there was gradual downward slope of the TAC, and T1/2 was prolonged compared to normal (13.99 min). Discussion/Conclusions: 99mTc-DTPA diuretic renal scintigraphy is an additional useful non-invasive tool in the differentiation of obstructive from non-obstructive urolithiasis in cats with adequate renal function.

Ureteral obstruction in a cat. Resolved obstruction after lithotripsy.

44

NORMAL THORACIC AND ABDOMINAL DISTRIBUTION OF 2-DEOXY-2-[18F]FLUORO-D-

GLUCOSE (18FDG) WITH POSITRON EMISSION TOMOGRAPHY IN ADULT CATS. F. Morandi F,1 A.K. LeBlanc,1 J.S. Wall,2 S.J. Kennel,2 A. Stuckey,2 B. Jakoby,3 D.T. Townsend,2 G.B. Daniel.4 1University of Tennessee College of Veterinary Medicine, 2University of Tennessee Graduate School of Medicine, Knoxville, TN , 37996; 3Siemens Molecular imaging, USA; 4Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, 24061. Introduction/Purpose: Positron Emission Tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (18FDG) has become a widespread imaging modality for the diagnosis and staging of neoplastic disease in humans. Limited data on this topic exist in veterinary medicine, and the normal distribution of 18FDG has been described to date only in dogs.1 The purpose of this study is to describe the normal 18FDG uptake in adult cats. Methods: Six adult female cats weighing 3.9 ± 0.5 (mean ± SD) kg and ranging in age from 3 to 10 years (mean ± SD, 4.5 ± 2.8 years) were studied. The cats were deemed normal based on the results of physical exam, routine blood work, thoracic and abdominal radiographs and abdominal ultrasound. After IV catheter placement, the cats were sedated using acepromazine and butorphanol at standard doses, then injected with 74.0 ± 13.0 (mean ± SD) MBq of 18FDG. Blood glucose was measured prior to 18FDG injection. Anesthetic induction was performed with a bolus of propofol IV; anesthesia was maintained with isoflurane. The cats were placed in ventral recumbency on the imaging platform (microPET P4, Siemens Molecular Imaging), and static images were acquired 2 hour post-injection. Three or four bed positions were necessary to capture the entire thorax and abdomen. A transmission scan was acquired using a 68Ge point source and used for attenuation and scatter correction. The images were inspected qualitatively; regions of interest (ROIs) were then drawn over the liver, right and left renal cortices, left ventricular wall, and walls of the ascending and descending colon; standardized uptake values (SUV) were calculated using standard formula.1 Results:

Of all tissues studied, the kidneys and intestinal tract had the most intense uptake of 18FDG, the liver activity was intermediate and the spleen was not identifiable in any of the PET images. Cardiac activity was variable but intense activity in the left ventricular myocardium was observed in most cats. No appreciable lung uptake was noted. Mean ± SD SUV values were calculated as follows: Myocardium (transverse)

Myocardium (sagittal)

Liver Right Kidney

Left kidney Ascending colon

Descending colon

3.58±2.57

3.34±2.77

1.00±0.30

1.33±0.13

1.16±0.09

1.35±0.56

1.14±0.30

Discussion/Conclusions: This study established the normal pattern of uptake of 18FDG in adult cats. These data establish a baseline uptake which can be used as a standard in future studies evaluating a variety of neoplastic and non-neoplastic feline diseases. References: 1) LeBlanc KA, Jakobi B, Townsend DW et al. Thoracic and abdominal uptake of 2-deoxy-2-[18F]fluoro-D-glucose (18FDG) with positron emission tomography in the normal dog. Vet Radiol

& Ultrasound 2008,49:182-188

45

SCINTIGRAPHIC FEATURES OF MULTIPLE ACQUIRED PORTOSYSTEMIC SHUNTS

USING TRANSPLENIC PORTAL SCINTIGRAPHY. F. Morandi,1 P.A. Sura,1 D. Sharp,1 G.B. Daniel.2 1University of Tennessee College of Veterinary Medicine, Knoxville, TN 37901, 2Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA, 24061. Introduction/Purpose: Ultrasound-guided percutaneous transplenic portal scintigraphy (TSPS) using 99mTcO4

- or 99mTc-Mebrofenin can be used to image the portal venous system in dogs.1,2 Only 6 cases of confirmed multiple acquired shunts (MPSS) have been described in the literature to date;1,3 in all cases, the shunts were visible as several discrete anomalous vessels on TSPS. Based on the authors’ experience, not all MPSS show a distinct plexus of vessels; the purpose of this abstract is to describe the scintigraphic patterns associated with MPSS. Methods: All confirmed cases of MPSS (via surgery or computed tomography, CT) seen at UTCVM or VMR-CVM between 11/2003 and 6/2008, were included in this review. All cases underwent TSPS (with 99mTcO4

- or 99mTc-Mebrofenin) according to established technique.1,2 A matching number of surgically confirmed single portocaval and portoazygos shunts were randomly selected from all cases seen at UTCVM in the same time period and used for comparison. The following parameters were evaluated: 1) presence of a single or multiple anomalous vessels; 2) presence of hepatofugal flow caudal to spleen and/or caudal to the cranial margin of the kidney; 3) presence of biphasic bolus. Transit time between peak splenic uptake to first cardiac uptake was recorded and compared between the two groups. Results: Fourteen cases met the inclusion criteria. Of these, 9 (64.3%) showed distinct multiple shunting vessels; 5 (35.7%) had biphasic bolus, indicative of fragmentation; all but one (92.9%) showed hepatofugal flow caudal to the cranial margin of the kidneys. In all single portocaval shunts a single anomalous vessel was identified; none showed hepatofugal flow caudal to the cranial border of the kidneys. Among portoazygos shunts, 4/14 (26.7%) showed flow caudal to the injection site in the spleen. Six portoazygos and 1 portocaval shunts had biphasic bolus. Median transit time from the spleen to the heart was significantly longer (1.9 s) for MPSS than for portocaval shunts (1.0 s, p<0.05), but not for portoazygos shunts (1.3 s). Discussion/Conclusions: Although TSPS does not show a distinct plexus of multiple anomalous vessels in all cases of MPSS, presence of hepatofugal flow caudal to the cranial margin of the kidney is commonly seen; longer transit time is also common compared to single portocaval shunts. Flow caudal to the splenic injection site but cranial to the kidney, and a biphasic bolus, however, can also be observed in cases of single congenital shunts. References: 1) Morandi F, Cole RC, Tobias KM et al. Use of 99mTcO4

- transplenic portal scintigraphy for diagnosis of portosystemic shunts in 28 Dogs. Vet Radiol & Ultrasound 2005;46: 153–161 2) Morandi F, Cole RC, Echandi R et al. Transplenic portal scintigraphy using 99mTc-mebrofenin in normal dogs. Vet Radiol & Ultrasound 2007,48:286-29 3) Sura PA, Tobias KM, Morandi F et al. Comparison of 99mTcO4

- transplenic portal scintigraphy with per-rectal portal scintigraphy for diagnosis of portosystemic shunts in dogs. Vet Surg

2007;36:654-660

46

THE EFFECTS OF IODINATED CONTRAST MEDIUM ADMINISTRATION ON THYROID SCINTIGRAPHY IN NORMAL CATS. W.R. Lee, C. R. Berry, A. P. Pease. Introduction/Purpose: There are many indications for thyroid scintigraphy in the hyperthyroid cat. Administration of iodinated contrast media has been reported to interfere with iodide uptake in the human thyroid gland and compromise diagnostic thyroid scintigraphy and radioiodine treatment for 4 to 6 weeks. 99mTechnetium pertechnetate (99mTcO4

-) is the most commonly used radionuclide in feline thyroid scintigraphy; however, the degree and duration of inhibition of thyroid tissue uptake of 99mTcO4

- by iodinated contrast medium had not been established in cats. The main objective of this study was to establish normal values for feline thyroid scintigraphy after intravenous iodinated contrast medium administration at specific time points in order to better understand the temporal characteristics of possible inhibition of 99mTcO4

- thyroid uptake. This data assists temporal planning of thyroid scintigraphy in cats that have undergone intravenous iodinated contrast medium procedures. Methods: Routine thyroid scintigraphy was performed in 7 cats by intravenous injection of 185 MBq (5 mCi) of 99mTcO4

- intravenously both 4 days before and 0,1, 3, 7,14 and 28 days after intravenous administration of 880 mg/kg iohexol (240 mg/ml). Thyroid scintigraphy data was used to calculate thyroid:salivary gland ratios (T:S) and the percentage of total injected 99mTcO4

- dose uptake within the thyroid at 20 minutes post injection (%TU). Each cat served as its own control and comparison of the each time point was performed using a one way repeated measures analysis of variance. The alpha level was placed at a p value of less than 0.05 for significance. Results: After iohexol administration, mean T:S was significantly decreased below baseline only on day 1 (p<0.01). No significant difference from baseline was noted in T:S at days 0, 3, 7, 14, 21, or 28 (p>0.3). At no point during the study did any cat have a T:S that fell below the published normal reference range (0.6-1.03). There was a significant decrease in %TU at day 1 (p<0.01) and also at days 3 and 14 (p=0.26 and p=0.39, respectively). At no point during the study, did any cat have a %TU that fell below the published normal reference range (0.19 ± 0.82). No significant difference from baseline was noted in %TU at days 0, 7, 21, or 28 (p>0.1). Discussion/Conclusions: There is mild decrease of T:S post intravenous iohexol administration at 880 mg/kg at 1 day following administration; however, this decrease is still within the normal reference range. There is also mild decrease in %TU at 1 and 3 days following iohexol administration, and minimal decrease at 14 days, though at all time points the values are within normal reference range. These changes, although statistically significant, are unlikely to be of clinical significance. However, to avoid mild decreases in these parameters, an interim of up to 1 day following intravenous administration of iohexol for T:S calculation and up to 3 days for %TU calculation is advised in normal cats. Further research using hyperthyroid cats is needed in order to provide the most accurate recommendations for such patients.

47


Friday, October 24, 2008 7:15 am CT/MRI Society Business Meeting – Tucker 8:00 am CT/MRI Keynote Speaker Address “Imaging of Arthritis Using Traditional and Non-Traditional Radiological

Methods” – Dr. Rebecca Laredo, MD 10:00 am Break With Exhibitors 10:30 am Scientific Session 4: CT/MRI Moderator: Tucker 10:30 am Time-Resolved Renal Contrast-Enhanced MRA in Normal Dogs –

Cavrenne 10:42 am Practical Application of Computed Tomography for Functional &

Anatomical Assessment in Canine Renal Artery Stenosis Model – Chang 10:54 am The Utility of Fat-Suppressed Postcontrast T1-Weighted MRI Sequences

in the Diagnosis of Spinal Diseases in Dogs: A Preliminary Report - Daniaux

11:06 am Break 11:18 am Associations Between Cardiopulmonary Parameters and a Flow-Void Sign

in the Mesencephalic Aqueduct of Small Breed Dogs – Freer 11:30 am Computed Tomographic Features of Feline Oral Squamous Cell

Carcinoma – Gendler 11:42 am Computed Tomographic Findings of Fungal Rhinitis and Sinusitis in 10

Cats – Karnik 11:54 am Improved Identification of the Palmar Fibrocartilage of the Navicular Bone

with Saline Magnetic Resonance Arthrography – Kerekes 12:00 pm Lunch

48

1:00 pm Poster Presentations B-Mode Ultrasonography and Evaluation of Normal Mature Dogs Brain:

Anatomic Correlation – Lorigados Comparison of Thoracic Radiography and Computed Tomography for

Detection of Pulmonary Nodules in Dogs – Bamford Clinical Experience with Stereotactic Radiosurgery for Extremity

Osteosarcoma – Ryan

Development of a Frame-Based Positioning and Immobilization Device For Stereotactic Radiosurgery of Extremity Neoplasia – Ryan

Computed Tomography of a Dog in the Prepatent phase of Heartworm Infection – Seiler

Slow Flow Artifact Mimicking Caudal Venal Caval Thrombosis on MRI – McKnight

Computed Tomography (CT) Imaging of Mediastinal & Axillary Lymph Nodes in Clinically Sound Rottweilers – Pinto Correlation of Signal Attenuation-Based Quantitative MRI with QCT Measurements – D’Anjou

1:30 pm “Veterinary Radiology Training at UC Davis – 1970 – 2007” – Dr. Tim

O’Brien 2:00 pm Scientific Session 5: CT/MRI, Continued Moderator: TBD 2:00 pm Correlation of Computed Tomographic and Radiographic Morphometric

Analysis of the Caudal Skull in Cavalier King Charles Spaniels with Neurologic Status - Knuppel

2:12 pm Utility of 3-Deoxy3 Fluorothymidine-Positron Emission Tomography/

Computed Tomography for Evaluating Response to Cytotoxic Chemotherapy in Dogs with Non-Hodgkin’s Lymphoma– Lawrence

2:24 pm Comparison Between T1-Weighted Fluid Attenuated Inversion Recovery –

Lora-Michiels 2:36 pm Multiphase Time Resolved Contrast-Enhanced Portal Magnetic

Resonance Angiography in Small Animals – Mai

49

2:48 pm Initial Experiences With a 3T MR System in a Veterinary Hospital –

Saveraid 3:00 pm Contrast-Enhanced Computed Tomography & Ultrasonography as Pre-

Operative indicators of Vascular Luminal Invasion of Adrenal Masses in Dogs - Schultz

3:12 pm Distal Abdominal Aorta Thrombosis in 4 Dogs diagnosed by Contrast-

Enhanced Time-of-Flight Magnetic Resonance Angiography - Sharpley 3:30 pm Break With Exhibitors 4:00 pm Scientific Session 6: CT/MRI, Continued Moderator: TBD 4:00 pm Magnetic Resonance Imaging of Canine Multiple Myeloma of the Vertebral

Column – Trevail 4:12 pm Magic Angle Effect in Normal Collateral Ligaments of the Distal

Interphalangeal Joint in Horses Imaged w/ a High-Field Magnetic Resonance Imaging System – Werpy

4:24 pm Magnetic Resonance Imaging Characteristics of Necrotizing

Meningoencephalitis in Pug Dogs - Young 5:00 pm Adjourn for the day

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TIME-RESOLVED RENAL CONTRAST-ENHANCED MRA IN NORMAL DOGS. R. Cavrenne, W. Mai Section of Radiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104. Introduction/Purpose: In humans, contrast-enhanced magnetic resonance angiography (CE-MRA) is commonly used to quantitatively and qualitatively evaluate renal vessels. It offers a safer alternative to computed tomography angiography (CTA). The aim of this study is to establish a renal MRA protocol in dogs using a 3D multiphase Fast Spoiled Gradient Recalled echo CE-MRA sequence (3D FSPGR CE MRA). Methods: Six clinically normal dogs were included in this study. The 3D volume for renal MRA was prescribed in a coronal oblique plane and encompassed both kidneys. The same volume was imaged four to five times in a row using the FSPGR sequence, starting immediately after the injection of gadolinium. We used an elliptical centric ordering of k-space to acquire the contrast sensitive data faster. A pre-contrast mask was acquired with the same parameters for all dogs just prior to the injection of gadolinium. Three different doses of gadolinium were tested (0.1mmol/kg; 0.25mmol/kg and 0.3mmol/kg) with a manual injection at an approximate rate of 2-3ml/sec, followed by a flush of saline. Acquisition was obtained with the animals in apnea. The mask was subtracted from the best arterial and venous phases and the subtracted series were then examined using planar reformatting and full- or sub-volume Maximum Intensity Projections. Results: The renal arterial and venous phases were obtained separately during phases 1 or 2, and 2 or 3 respectively. The renal arteries and veins were clearly visualized. The total acquisition time ranged between 40-65 seconds (10 to 13 sec per 3D volume acquisition). In one dog the arterial phase was not optimal and artifacts were present but the arteries were still well visualized during the venous phase allowing for an adequate anatomic depiction of all renal vessels. Discussion/Conclusions: Multiphase CE-MRA with an elliptical centric k-space ordering allows distinguishing renal arterial and venous phases in dogs without bolus timing, and can be used as a non invasive diagnostic imaging alternative to map renal vessels. Potential applications include screening of renal donors in renal transplantation programs, and the pre-treatment evaluation of animals with invasive renal neoplasia or vascular anomalies when surgery or embolization are contemplated. MRA has several advantages over CTA: (1) Gadolinium contrast agents used in MRA have a more favorable safety profile than iodinated agents; (2) The imaging plane of 3D MRA acquisitions can be adjusted to fit the anatomy of the target vascular territory with higher resolution and fewer slices; (3) Reconstruction of projection images from a 3D CE-MRA data set is considerably simpler than from a 3D CTA data set (no effort is required to eliminate bone or other dense structures which might obscure the vascular anatomy); (4) MRA images are acquired without ionizing radiation. The multiphase approach can be used with a variety of MRI scanners without the need for specific hardware or software.

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PRACTICAL APPLICATION OF COMPUTED TOMOGRAPHY FOR FUNCTIONAL AND ANATOMICAL ASSESSMENT IN CANINE RENAL ARTERY STENOSIS MODEL. Chang JH, Kim SJ1, Byeon YE, Lee HY, Yoon JH, Choi MC, 1Department of Nuclear Medicine, Seoul National University College of Medicine, College of Veterinary Medicine and BK21 Program for Veterinary Science, Seoul National University, Seoul, 151-742, South Korea. Introduction/Purpose: Computed tomography (CT) could provide functional information of the kidney through measuring contrast media clearance using dynamic single-slice scan and obtaining triphasic helical imaging. This study was to investigate changes of computed tomography-glomerular filtration rate (CT-GFR) and to evaluate morphologic parameters in canine renal artery stenosis (RAS) model. Methods: Animals: Three male beagle dogs were used as RAS model. Procedure: Surgical partial ligation (approximately 50% stenosis) of the left renal artery was carried out. The renal CT protocols involved the following three steps; precontrast helical scan, single-slice dynamic scan, and postcontrast helical scan including CT angiography and nephrographic phase. Before induction of RAS, normal CT-GFR value, renal vascular pattern and whole renal parenchyma were evaluated through renal CT examination. A planned repeat renal CT scan was performed with a 1 week interval for four weeks. Results: Normal reference values of three dogs were 3.61, 4.42, 2.94 ml/min/kg, respectively. In the RAS model, CT-GFR values were decreased by less than 1.0 ml/min/kg during 4-week-monitoring. Due to partial hypoperfusion and ischemic injury, the renal volume was gradually diminished (about 50% and less of original renal volume). Multifocal perfusion defect of renal parenchyma were found during the nephrographic phase. Discussion/Conclusions: Renal CT protocols including functional CT and triphasic helical CT are very practical and helpful to obtain superior physiologic and morphologic information of the kidney in the RAS model.

52

THE UTILITY OF FAT-SUPPRESSED POSTCONTRAST T1-WEIGHTED MRI SEQUENCES IN THE DIAGNOSIS OF SPINAL DISEASES IN DOGS: A PRELIMINARY REPORT. L. Daniaux, M.-A. d’Anjou, E. N. Carmel, From the Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada. Introduction/Purpose: Magnetic resonance imaging (MRI) is recognized as the most useful modality to assess spinal diseases in dogs. While MRI protocols typically consist of T2-weighted and T1-weighted (T1w) fast spin echo (FSE) sequences, several other FSE and gradient echo sequences can further characterise tissues and enhance lesion conspicuity. We describe the utility of chemical fat suppression (FS) used with postcontrast T1w sequences in the diagnosis of different types of spinal diseases in dogs. Methods: Dogs with different types of clinically-diagnosed spinal disorders in which 1.5 Tesla MRI (GE Signa HDx) was performed using high-quality, postcontrast T1w FSE sequences with fat suppression (T1-FS) were selected. For each dog, postcontrast T1w-FS images were compared to other sequences to determine the benefit of these additional sequences. Results: Six dogs with different types of pathologies were included in this descriptive study. In one dog with lumbosacral discospondylitis, postcontrast T1w-FS images allowed to more clearly identify contrast enhancement of the vertebral bodies, epidural fat and paravertebral musculature. In another dog with vertebral lymphoma, infiltration of the vertebral body, canal and spinous process was most conspicuous on postcontrast T1w-FS images. A prominent rim of contrast enhancement was clearly seen on transverse postcontrast T1w-FS images of a dog affected with severe meningitis. In a dog with lumbar meningioma, dural tail signs were more obvious on dorsal postcontrast T1w-FS. Dorsal postcontrast T1w-FS images also allowed to more clearly define the extension of a sciatic nerve sheath tumor in another dog. In a dog with C6-7 foraminal disc herniation and nerve impingement, distinct epidural and paravertebral contrast enhancement was observed on T1w-FS along the path of the affected nerve root and delineating the hypointense extruded material, allowing a more confident diagnosis. Discussion/Conclusions: Fat suppression techniques on MRI result in a signal reduction of the normal fat that composes the vertebral bone marrow, epidural space, foramina and paravertebral fat planes without affecting the signal from soft tissues or liquids. On T1w sequences, abnormal contrast-enhancing tissues surrounded by suppressed fat can therefore be visualized with more conspicuity. The increased lesion-to-background contrast also allows to more clearly define the extension of these processes. Our findings described in these selected cases highlight the potential benefit of using fat suppression with postcontrast T1w FSE sequences in different categories of spinal diseases. Further studies comparing postcontrast T1w sequences with and without fat suppression are required to define whether FS sequences should be used systematically in the MRI evaluation of spinal diseases in dogs.

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ASSOCIATIONS BETWEEN CARDIOPULMONARY PARAMETERS AND A FLOW-VOID SIGN IN THE MESENCEPHALIC AQUEDUCT OF SMALL-BREED DOGS. Freer SR, Scrivani PV, Erb HN. Cornell University, College of Veterinary Medicine, Ithaca, NY, 14853. Introduction/Purpose: The cerebrospinal fluid flow-void sign (CFVS) is an observable signal loss from cerebrospinal fluid, especially on T2-weighted MR images. In people, this sign is attributed to rapid flow or turbulence from arterial pulsations and may be a visual distracter or diagnostic clue. We have observed a similar appearance in dogs undergoing MRI and associated the presence of this sign in small-breed dogs with increased ventricular size and syringomyelia. The cause of the sign is unproven in dogs and, if related to CSF flow as in people, it may be affected by cardiovascular parameters during general anesthesia. Therefore, the purposes of this study are to describe the CFVS, including the proposed physical principles behind this sign, and test whether its appearance in dogs is associated with certain anesthetic variables. Methods: The sample population consisted of 53 small-breed (<15 kg) dogs undergoing spin echo, T2-weighted MRI of the neurocranium. Following review of the medical record and MR images, the heart rate, end-tidal CO2 and blood pressure (systolic, mean and diastolic) were recorded and dogs were grouped as having a CFVS in the mesencephalic aqueduct or not. A Kolmogorov-Smirnov test confirmed normality of the data. Results: No statistically significant difference was detected between dogs with or without a CFVS for heart rate, end-tidal CO2 or blood pressure measurements: statistical power showed that a Type-II error was unlikely. Discussion/Conclusions: Detection of CFVS in small-breed dogs is unlikely related to heart rate, end-tidal CO2 or blood pressure measurements during general anesthesia when using routine anesthetic protocols.

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COMPUTED TOMOGRAPHIC FEATURES OF FELINE ORAL SQUAMOUS CELL CARCINOMA. Gendler A1, Lewis J2, Reetz J2, Schwarz T1. 1School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706 and 2University of Pennsylvania School of Veterinary Medicine, Philadelphia PA 19104-4107. Introduction/Methods: A retrospective review of 18 cats with confirmed oral squamous cell carcinoma (SCC) that underwent computed tomography (CT) examination was performed. The objective of the study was to describe the CT features of feline oral SCC. Additionally, quantitative CT features were tested for correlation with survival time. Results: On CT examination, SCC was seen in the sublingual (38.9%), maxilla (27.8%), buccal (22.2%), pharyngeal (11.1%) and soft palate mucosa (5.6%), and the mandible (22.2%). These results were in agreement with oral exam findings for all soft tissue locations except the soft palate (22.2% on oral exam). Upon CT exam, extension of the mass into the orbit (27.8%) was seen more often than extension into the nasal cavity (5.6%) or cranial vault (5.6%). Nearly all masses had marked contrast enhancement (94.4%) and heterogenous contrast enhancement pattern was present most often. Osteolytic lesions associated with the soft tissue mass were seen in 50% of cats. Ipsilateral lymphadenopathy was present in 38.9% of cats. None of the quantitative CT features, including mass size, post-contrast attenuation or ipsilateral lymph node width, correlated with survival time. No significant differences were found between survival times of patients grouped for the presence or absence of osteolytic lesions or lymphadenopathy. Discussion/Conclusions: Common CT features of feline oral SCC include localization to the sublingual and maxillary mucosa, marked heterogenous contrast enhancement and osteolysis. CT defined mass extension and facilitated lymph node staging, but quantitative CT features did not correlate with survival time.

55

COMPUTED TOMOGRAPHIC FINDINGS OF FUNGAL RHINITIS AND SINUSITIS IN 10 CATS. Ketaki Karnik, Jean K. Reichle, Anthony J. Fischetti, Justin M. Goggin. The purpose of this retrospective study was to describe the computed tomographic (CT) findings of fungal rhinitis/sinusitis in cats. The CT images of 5 domestic short hair, three Persian, one domestic long hair, and one Siamese cat ranging from 7-13 years of age were examined. The mean age was 10.8 years and all were neutered males. Nasal aspergillosis was diagnosed in 5 cats, cryptococcosis in 3 cats, hyalohyphomycosis in 1 cat, and trichosporonosis in 1 cat. Most cats had bilateral disease, abnormal soft tissue attenuation in 2/3 of the nasal cavity, and turbinate lysis. Most cats also had lysis of the hard palate, nasal septum or frontal bone. One cat had lysis of the cribriform plate. The majority of cats whose lymph nodes were imaged had lymph node enlargement. The nasal cavities of all cats contrast medium enhanced with either a primarily peripheral rim or heterogeneous pattern. There is overlap of clinical signs, age, and CT features of cats with nasal neoplasia and those with fungal rhinitis/sinusitis. Mycotic rhinitis should be considered when evaluating cats with nasal disease.

56

IMPROVED IDENTIFICATION OF THE PALMAR FIBROCARTILAGE OF THE NAVICULAR

BONE WITH SALINE MAGNETIC RESONANCE ARTHROGRAPHY. Z Kerekes, MC Schramme and A Pease, North Carolina State University, Raleigh, NC, 27606.

Introduction/Purpose: Navicular disease is the most common cause of hoof lameness in horses. Degeneration of the palmar fibrocartilage of the navicular bone is the earliest and most common pathological finding in horses with navicular disease. Our hypothesis is that the injection of the navicular bursa with saline prior to magnetic resonance imaging (MRI) of the digit will result in improved accuracy in measuring the thickness of the palmar fibrocartilage of the navicular bone and improved sensitivity in detecting areas of fibrocartilage degeneration in comparison with MRI without contrast. Methods: Thoracic-limbs were collected from 22 horses within 6 hours of being euthanized for any reason and stored in a -40°F freezer until imaged. The limbs were then thawed in a water bath for 24 hours prior to imaging. Imaging consisted of a sagittal 2D proton density sequence with a slice thickness of 3.5 mm and a transverse 3D Flash sequence with fat saturation and slice thickness of 2.0 mm, both before and after injection of the navicular bursa with 6-10 cc 0.9% saline. Navicular bones were then removed and the fibrocartilage was stained with Indian ink to map areas of degeneration. Digital photographs of the stained navicular bones were obtained. The MR images were evaluated blindly by a board certified radiologist (AP) and compared to the gross pathology findings. Sensitivity, specificity, positive and negative predictive values were then calculated for each image sequence using standard calculations. Results: The sensitivity for the PD-weighted images were similar (50%), while the T1-weighted images were 17% without contrast medium and 50% with contrast medium. The specificity increased with contrast medium on PD-weighted images (pre=60%, post=88%) and decreased with the T1-weighted images (pre=81%, post=63%).The positive predictive value of the PD-weighted images increased from 33% to 60% with contrast medium and increased from 25% to 33% with contrast medium on the T1-weighted images. The negative predicative values also increased from 75% to 82% for the PD-weighted images when contrast medium was introduced and from 72% to 77% when contrast medium was used in the T1-weighted images. Discussion/Conclusions: The palmar fibrocartilage has intermediate signal intensity and is not contrasted by an adjacent high intensity layer of synovial fluid because it is tightly apposed against the dorsal surface of the deep digital flexor tendon. There is little contrast between the medium intensity signal of fibrocartilage and the high intensity of the traditional MR contrast agent Gadolinium on T1-weighted sequences. Better cartilage contrast can be obtained following injection of saline into the synovial space, as saline produces hypointense signal that is very different from the intermediate high intensity signal of fibrocartilage. In addition, distension of the bursa with any fluid physically separates the palmar fibrocartilage of the navicular bone and the dorsal surface of the DDFT, which results in an improved visibility of both surfaces on MR images. Injection of saline into the navicular bursa during MR imaging of patients in this population had an improved positive and negative predicative value for all sequences. This means that injection of contrast medium improved the ability to correctly evaluate the fibrocartilage integrity using PD and T1-weighted imaging.

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B-MODE ULTRASONOGRAPHY IN EVALUATION OF NORMAL MATURE DOG’S BRAIN: ANATOMIC CORRELATION. C. A. B. Lorigados, A. C. B. C. Fonseca-Pinto, F. A. Sterman. School of Veterinary Medicine and Animal Science University of Sao Paulo, Brazil 05508270 Introduction/Purpose: Ultrasound imaging of the brain can be performed through the fontanelles in young animals, mainly for the diagnosis of hidrocephalus. However its use in mature dogs is restrictet by the bones of the skull. Important attenuation artifacts are caused by the difference in the speed of the sound within bone and soft tissue. The purpose of this study was to evaluate the possibility to examine the normal mature dog’s brain with ultrasound throught the intact skull and correlate ultrasound images with the brain “in vitro.” Methods: Ten postmortem mesaticephalics normal mature dogs were examined. The ultrasound examinations were conducted using a 3-5 MHz curvilinear scanner, through the intact temporal, lateral portion of the parietal bones and the foramen magnum. The images were acquired in transversal and dorsal planes. At the conclusion of the ultrasonography, the heads were frozen and then sectioned for anatomic correlation. The measures of thickness the temporal and parietal bones were obtained in transversal plane. Results: It was possible obtain ultrasound images in all dogs examined. In this study, the intracranial structures identified using B-mode ultrasound included: lateral ventricles, longitudinal fissure, some brain sulci, cerebellum, tentorium cerebelli, diencephalon and hippocampus. Direct measures of thickness of the temporal and parietal bones were 0.15-0.20 cm e 0.30-0.35cm, respectively. Discussion/Conclusions: The present report shows that the temporal, lateral portion of the parietal (compact and thin bones) and the foramen magnum can be used as acoustic windows for real-time sonographic imaging of the brain in mature dogs. However the images resolution is inferior compared to the features obtained through the fontanelle or craniotomy. Further studies will need to be performed to evaluate the ultrasound imaging in mature dogs with brain diseases.

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COMPARISON OF THORACIC RADIOGRAPHY AND COMPUTED TOMOGRAPHY FOR DETECTION OF PULMONARY NODULES IN DOGS. A. Bamford, L.J. Armbrust, D.S. Biller, R. Chun, L.D. Garrett, M. Sanderson. Kansas State University, KS, 66502. Introduction/Purpose: Pulmonary metastatic disease is a common sequela of many neoplastic diseases. In veterinary medicine 3 view radiographs are considered the standard, although CT has become more widely available for use. In people CT is considered the gold standard for detection of pulmonary nodules. This study investigates the effectiveness of computed tomography (CT) compared to standard 3 view thoracic radiographs for the detection of pulmonary nodules in dogs with confirmed neoplastic disease. Methods: Thirty-three dogs ranging in age from 5-15 years (mean 9.3 ± SD 2.8) were included. There were 25 large to giant breeds, and 8 toy, small, and medium breeds. All dogs had histological confirmation of neoplasia. The type of neoplasia that was most prevalent was osteosarcoma (13 dogs). Each patient had a three view radiographic study obtained consisting of right and left lateral and ventrodorsal views. Radiographs were evaluated by three reviewers that were blinded to the patient information. All three films from a study were interpreted together. The location and size of pulmonary nodules were recorded. Helical CT scans with a slice thickness of 3-7 mm, dependent on body size, and a pitch of 1 were performed within 7 days of the radiographs. The dogs were ventilated with 4 breaths followed by a breath hold, at 20 cmH20, for the length of the scan. The CT scans were evaluated in a lung window by a radiologist blinded to patient information. The location and size of the pulmonary nodules were recorded. Results: Twenty-one of the 33 dogs (64%) had pulmonary nodules/masses detected on CT. Of these 21 dogs, 17 (81%) had pulmonary nodules/masses detected on radiographs. Two of 33 dogs (6%) were diagnosed as having a pulmonary nodule on radiographs that was not confirmed on CT. In the 17 dogs that had nodules visible on radiographs that were confirmed on CT, radiographs underestimated the number of nodules in 6 dogs. The four dogs that were negative for nodules on radiographs, but positive on CT were all large to giant breed dogs with osteosarcoma. Nodule size in these dogs ranged from 2 mm to 2 cm. Radiographs detected 37 nodules ranging in size from 3 mm to 10 cm. CT detected 89 nodules ranging in size from 2 mm to 8 cm. Discussion/Conclusions: As would be expected based on past and current literature, CT is more sensitive than radiographs for detection of pulmonary nodules. In dogs three view thoracic radiographs will likely remain the standard for evaluation of pulmonary metastatic disease due to lower cost and increased availability compared to CT. Because small to moderate sized nodules in large to giant breed dogs proved more difficult to detect, it may be beneficial to recommend CT in large breed dogs with osteosarcoma if the detection of nodules will change therapy (surgical amputation vs. no amputation). Future studies would be helpful to asses the impact on long-term survival of early detection of pulmonary metastases with CT in dogs with osteosarcoma.

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CLINICAL EXPERIENCE WITH STEREOTACTIC RADIOSURGERY FOR EXTREMITY

OSTEOSARCOMA. S.D. Ryan, J. Tuohy, J.F. Harmon, B.K. Arceneaux, S.M. LaRue. Animal Cancer Center, Colorado State University, Fort Collins, CO, 80523. Introduction/Purpose:

Stereotactic radiosurgery (SRS) treatment of canine extremity osteosarcoma (OSA) has shown promise in a clinical case series. [Farese et al., JAVMA 2004] Current surgical limb-sparing options are limited to the distal radius site and can have complications including implant failure, infection and local tumor recurrence. SRS delivers high dose curative-intent radiation to tumor volume with a sharp decrease in dose to adjacent normal tissues. This treatment modality provides local pain palliation and may provide a non-surgical limb salvage option in a variety of anatomic locations that avoids complications associated with surgical limb sparing. Methods:

Five client-owned dogs received SRS for treatment of primary or metastatic extremity OSA. A frame-based immobilization system was used for reproducible positioning for radiation planning CT and SRS treatments. A hypofractionated stereotactic radiation therapy protocol using 3 fractions at intervals of 2-3 days delivering a total dose of 54-60 Gy to the tumor was used. Radiation plans were generated using the Varian Eclipse™ treatment planning system, and administered using the Varian Trilogy Linear Accelerator™. PTV included both the boney and soft tissue component of the tumor. Positioning was verified with orthogonal KV image guidance at each treatment session. Dose was administered using 5-7 beams. Concurrent carboplatin chemotherapy and intravenous pamidronate therapy was given in the majority of cases. Response to therapy was assessed by clinical function and radiographs. Results: Early follow up results for this new therapy are encouraging. Patient 1 presented with left distal tibia OSA is doing well 6 months post-treatment. A focal non healing skin wound developed on the lateral tarsus that corresponded to the highest skin dose. This was successfully treated with a local transposition flap. Patients 2 and 3 presented with left distal radius OSA, and are doing well 5 and 2 months post treatment. Patients 4 and 5 have completed treatment with one month follow up. There was a subjective decrease in lameness in all patients after treatment. Serial lesion radiographs indicate significant re-calcification of the lytic regions. There have been no pathologic fractures or detectable evidence of local tumor progression or metastatic disease in these patients to date. Discussion/Conclusions:

The SRS, chemotherapy and bisphosphonate protocol described provides radiographic evidence of decreased osteolysis, subjective durable pain palliation and clinically improved limb function. Acute skin effects have been mild and focal in nature. The non healing ulcer that occurred in one dog was easily repaired. Retrospective evaluation of dose volume histogram information was used to modify maximum skin dose in subsequent patients and will help define normal tissue tolerance to prevent this type of effect. There have been no incidents of pathologic fracture in these patients the main long term complication seen in a previous report with SRS for extremity OSA. However, follow up time is still less than 8 months. A prospective clinical study has started which evaluates dynamic contrast enhanced MRI (DCE-MRI) perfusion parameters, percent tumor necrosis, bone turnover biomarkers and force plate gait analysis to provide objective measures of response to therapy.

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DEVELOPMENT OF A FRAME-BASED POSITIONING AND IMMOBILIZATION DEVICE FOR

STEREOTACTIC RADIOSURGERY OF EXTREMITY NEOPLASIA. S.D. Ryan, J.F. Harmon, J. Tuohy, S.M. LaRue Animal Cancer Center, Colorado State University, Fort Collins, CO 80523. Introduction/Purpose: Stereotactic radiosurgery (SRS) is an evolving treatment option for patients with extremity osteosarcoma (OSA). Clinical experience at the University of Florida and now at Colorado State University (CSU) using SRS for extremity OSA has been encouraging. This treatment modality provides local pain palliation and may provide a non-surgical limb salvage option for patients. A hypofractionated stereotactic radiation therapy plan with adjuvant chemotherapy and bisphosphonate therapy is used at CSU. Patients receive 3 fractions at intervals of 2-3 days for a total dose of 54-60 Gy to the tumor and maximum 40 Gy to the focal skin region closest to the tumor. Positioning and immobilization systems are required for accurate, repeatable patient positioning during planning CT scan and SRS treatments. These systems can be frame-based, anchored to bone, or frameless using optical infrared tracking systems and fiducial markers. We describe the development of a frame-based system for treatment of extremity neoplasia. Methods: The positioning device consists of a clear Plexiglas platform with indexed holes that attach it to the CT or linear accelerator couch. Two 84mm diameter IMEX™ carbon fiber circular fixator rings are placed proximal and distal to the tumor with 1.6mm opposing olive fixator wires tensioned to 30-50kg tension. Four 2-hole IMEX posts on the base platform provide the attachment points for the carbon fiber rings. (Fig. 1) A repeatability experiment was performed by positioning an instrumented canine cadaver forelimb in the indexed frame on ten occasions. Five clinical cases have been treated with SRS using this immobilization system (2 distal radius OSA, 2 distal tibial OSA and 1 distal humerus soft tissue sarcoma). Results: High repeatability within 2mm in the x,y,z planes was demonstrated in the cadaver limb experiment. Positioning in the clinical cases was repeatable based on comparison of bony anatomy landmarks from orthogonal view kilovoltage or cone beam CT images obtained from the onboard Trilogy™ imaging system to the planning CT images. Patients tolerated the fixator rings well and ambulated normally during the 10 days of CT planning and SRS treatments. Discussion/Conclusions:

Currently,this positioning system works most effectively with OSA lesions in the distal limb. Modifications of the external fixator pin placements have been developed for patients with OSA of the proximal humerus or femur. A frame based positioning system has the advantage of decreased cost compared to optical infrared frameless systems making SRS more feasible for veterinary radiation oncology.

Fig. 1 Patient with distal tibia OSA

positioned in frame-based system

for planning CT. The red indexing

pin and bar connects the frame to

the CT couch. The patient is

attached to the frame by the circular

fixator rings that are attached to 2-

hole posts on the frame base plate

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COMPUTED TOMOGRAPHY OF A DOG IN THE PREPATENT PHASE OF HEARTWORM

INFECTION. G.S. Seiler, T.J. Nolan, E. Withnall, C. Reynolds, J.B. Lok, M. Sleeper. University of Pennsylvania School of Veterinary Medicine, PA, 19104. Introduction/Purpose: Testing for and treatment of heartworm disease depends largely on the life cycle of the heartworm. There are 2 larval stages in the dog before the immature adult worms enter the vascular system and migrate to the pulmonary arteries where they mature into adult heartworms and begin to produce microfilariae. Diagnostic tests may be negative throughout this period known as the prepatent phase. The purpose of this case study is to describe Computed Tomographic (CT) and CT angiographic findings in a dog in the prepatent phase of experimental infection with Dirofilaria immitis. Methods: A 3 month old Beagle reared in a specific pathogen-free environment was purchased from a USDA licensed breeder. The puppy was inoculated with 30 L3 larvae of Dirofilaria immitis. A CT scan, echocardiography and thoracic radiography were performed at 4, 5.5 and 7 months post infection. The CT protocol included a helical survey image series followed by CT angiography. Dynamic CT, acquired in a single location centered on the main pulmonary arteries during injection of a small volume of contrast medium, was used to determine timing of contrast arrival for the CT angiogram. Images were viewed lung and soft tissue windows to assess pulmonary parenchymal changes and filling defects in the pulmonary arteries. Results: Changes seen 4 months after infection included an enlarged and tortuous peripheral right caudal pulmonary artery. In the surrounding pulmonary parenchyma there were small areas of increased attenuation with a ground-glass appearance. In subsequent scans the tortuous segment increased in size and there were similar lesions apparent in the left caudal lung lobe (after 5.5 months) and accessory lung lobe (7 months). Abnormal pulmonary parenchyma was seen in areas of newly apparent vascular changes, whereas previous infiltrates had disappeared. The angiogram was normal at 4 and 5.5 months. At 7 months a filling defect was evident in the distal segment of the right caudal pulmonary artery. Echocardiography was normal at all time points. At 7 months an enlarged and blunted caudal lobar pulmonary artery was visible radiographically. Presence of microfilariae in the peripheral blood was confirmed at 7 months, although the dog was still antigen negative. Discussion/Conclusions: The case presented here shows the CT features of canine heartworm disease in an early phase of infection. Damage to the vessels occurs shortly after the young adults reach the pulmonary arteries, likely causing the enlargement of the peripheral vessels seen in this case. The immature adult worms can cause eosinophilic pulmonary infiltrates, which may be the reason for the observed areas of interstitial pattern. The partial obstruction of the right caudal pulmonary artery 7 months after infection corresponds with the expected development of mature adult worms in this site. The right caudal lung lobe is a commonly observed predilection site for the highest worm burden; it is where we observed the earliest and most severe changes in this dog as well. Knowledge of possible CT findings in the prepatent phase of heartworm infection such as in this confirmed case may be useful when evaluating the pulmonary parenchyma in canine patients, especially since laboratory testing usually is negative in this stage.

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SLOW FLOW ARTIFACT MIMICKING CAUDAL VENAL CAVAL THROMBOSIS ON MRI. A. McKnight, J. Posh, M. Alonso, L. Mundt. AnimalScan, PA 18020

Introduction/Purpose: Abnormal hyperintense signal within the caudal vena cava is present in some dogs undergoing routine spinal magnetic resonance imaging. The signal characteristics and contrast enhancement patterns can be strongly suggestive of a large thrombus. The purpose of this study was to demonstrate that this abnormal signal does not represent a thrombus formation, but rather an artifact of slow flow. Methods: MRI exams were performed on five dogs presented for T3-L3 spinal cord lesions, including 2 Great Danes, 1 Beagle, 1 Great Pyrenees, and 1 Lhasa Apso, ranging in age from 3-7 years with an average age of 5.2 years. The MRI system used was a 0.3T AIRIS II scanner (Hitachi Medical Systems America) and included T1W and T2W imaged in the sagittal, axial, and dorsal planes. The extremity or small body wrap coil was used depending on the size of the dog. In two of the animals, gadolinium contrast was used and T1 imaging repeated in at least two planes. In one additional normal animal, a10yo German Shepherd dog, the caudal vena cava was specifically scanned with the above pulse sequences, as well as repeat sequences with swapped phase and frequency directions, and a time of flight MR angiographic pulse sequence. Results: All of the clinical dogs demonstrated some intermediate intensity signal in the caudal vena cava on the sagittal T1 and T2 images, just caudal to the level of the renal veins. When gadolinium was used, the signal intensity of the artifact increased dramatically as seen with contrast enhancement. In the giant breeds, the signal characteristics were particularly striking on both pre- and post-contrast sequences, including a very sharp demarcation between the hypointense signal void within the caudal vena cava cranial to the level of the renal veins, and the uniform, marked hyperintense signal more caudally. The presence of this signal in five dogs without clinical signs of caudal venal caval thrombosis, and within a four month time frame suggested an artifact of slow flow was responsible. The normal animal also demonstrated the same striking hyperintense signal artifact with the same pulse sequences, with the exception that the hyperintense signal disappeared following the swapping of the phase and frequency directions and the MR angiographic technique.

Discussion/Conclusions: The presence of flow artifacts in arteries and veins is often seen and well known. As the chosen scanning parameters, presence of saturation pulses, slice order, magnetic field strength, as well as blood flow velocity and direction of flow relative to the slice can alter the signal of blood within the vena cava, it is important to recognize artifacts, as both slow flow and thrombus can contribute to the signal noted. In conclusion, it is not uncommon for the caudal vena cava to have an artifactual increased signal on routine MRI of the thoracolumbar that can mimic a large thrombus, particularly in large breeds. When clinically indicated, swapping phase and frequency directions or performing an MR angiographic sequence will better differentiate artifact from thrombus.

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COMPUTED TOMOGRAPHY (CT) IMAGING OF MEDIASTINAL AND AXILLARY LYMPH NODES IN CLINICALLY SOUND ROTTWEILERS. A.C.B.C.Fonseca–Pinto1, E.A.R. De Freitas, C. Figueiredo2. 1School of Veterinary Medicine and Animal Science of the University of São Paulo, São Paulo – SP, Brazil, 05508-000. 2 Fleury Diagnostic Center, São Paulo – SP, Brazil, 01333-031. Introduction/Purpose: Trough CT it is possible to evaluate lymph nodes in detail and to detect changes in these structures earlier than with Xray and ultrasound. Lack of information in the veterinary literature directed the focus of this report to normal aspects of CT imaging of the axillary and mediastinal lymph nodes of adult dogs. Methods: A CT scan of 14 normal adult male and female Rottweilers was done. To define them as clinically sound anamnesis, physical examination, complete blood count, renal and hepatic biochemistry, ECG, and thoracic X ray where done. After de intravenous injection of hydro soluble ionic iodine, approximately 1,5ml/kg 2/3 at once and the rest through continuous infusion, contiguous 10mm transverse images were obtained from the beginning of the thorax until the aortic arch with a an axial scanner (CTMAX 640 GE). In the obtained images mediastinal and axillary lymph nodes where looked for and when found measured in their smallest diameter and their attenuation compared to that of musculature. Mean and standard deviation of: age, weight, body length and the smallest diameter of the axillary and mediastinal lymph nodes where determined. Results: Mean and standard deviation of parameters: age 4 +-2.04 years; weight 41.79 +- 4.63 kg; body length 89.61 +- 2.63 cm. Axillary lymph nodes were seen in 64.29% of the animals, mean of the smallest diameter was 3.27 mm with a standard deviation of 1.94 and a minimum value of 1mm and a maximum value of 7mm. 68.75% of the lymph nodes were hypodense when compared to musculature and 31.25% were isodense. Mediastinal lymph nodes were identified in 71.43% of the animals, mean measure of the smallest diameter was 4.54mm with a standard deviation of 2.63 and a minimum value of 1 and a maximum value of 8mm. 84.61% of the lymph nodes were hypodense when compared to musculature and 14.29% were isodense. Discussion/Conclusions: The results show that it is possible to visualize axillar and mediastinal lymph nodes in adult clinically sound Rottweilers with CT using 10mm width transverse slice and interval. The smallest diameter of the axillary lymph nodes should not surpass 7mm and that of the mediastinal lymph nodes 8 mm. Their attenuation should be equal or smaller then that of musculature in the contrasted scan. The use of new generation helicoidal certainly will shed new and better information improving use and interpretation of tomographic images.

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CORRELATION OF SIGNAL ATTENUATION-BASED QUANTITATIVE MRI WITH QCT

MEASUREMENTS OF SUBCHONDRAL BONE DENSITY IN RACEHORSES WITH METACARPOPHALANGEAL OSTEOARTHRITIS. J. Olive†, M.-A. d’Anjou*, Kate Alexander*, Guy Beauchamp*, Christine Théoret†, From the *Departments of Clinical Sciences and †Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Québec, Canada. Introduction/Purpose:

Several studies report the relationships that prevail between subchondral bone density and cartilage in humans and animals, some of which using quantitative computed tomography (QCT). Due to its great capacity to assess all joint components, magnetic resonance imaging (MRI) has become the ideal modality to assess morphological changes in OA. While it is known that increased bone marrow density results in signal reduction on MRI, the capacity of MRI to quantify bone density in osteoarthritis (OA) has not been described. We evaluated the correlation of signal attenuation-based quantitative MRI (QMRI) with QCT in racehorses with naturally-occurring metacarpophalangeal joint OA. Methods:

Three 1.5 T MRI sequences [dorsal and transverse 3D T1-weighted gradient echo (T1-GRE), dorsal 3D T2*-weighted GRE Fast Imaging Employing Steady sTate Acquisition (FIESTA)] and transverse single-slice computed tomography (CT) were acquired ex vivo. MRI signal intensity and CT attenuation were quantified in six regions of interest (ROI) in the subchondral bone of 20 equine metacarpal condyles (Fig.1). To correct for signal noise and contrast variations on MRI, separate ROIs were drawn in the air close to the joint and ROIcorr=ROI/Air ratios were generated. CT attenuation was corrected using a calibration phantom to obtain K2HPO4 equivalent density in mg/ml of bone. The correlation between QMRI-ROIcorr, using different MRI sequences, and QCT measurements were evaluated. Also, the intraobserver repeatability of ROI measurement on 2 occasions was tested for each modality.

Results: Repeatability of measurements was excellent for QCT (R =98.3%) and for QMRI (R =98.8%), with no bias between the two evaluations for either modality. As expected, increased bone density on CT was associated with a reduction in bone marrow signal intensity on MRI. Good negative correlation was found between transverse (R =77%) or dorsal (R =77%) T1-GRE and QCT measurements of bone density (p<0.0001), and between dorsal T2*-FIESTA and QCT (R =80%, p<0.0001). Discussion/Conclusions:

In this form of equine OA and using specific MRI sequences, signal attenuation-based QMRI appears to be a reliable, clinically-applicable method to indirectly estimate subchondral bone density.

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CORRELATION OF COMPUTED TOMOGRAPHIC AND RADIOGRAPHIC MORPHOMETRIC ANALYSIS OF THE CAUDAL SKULL IN CAVALIER KING CHARLES SPANIELS WITH NEUROLOGIC STATUS. J.M. Knuppel, V.F. Samii, L.K. Cole, S.O. Wagner, R.L.Echandi. Department of Veterinary Clinical Sciences, The Ohio State University, Ohio, 43210.

Introduction/Purpose: Caudal occipital malformation syndrome (COMS) is a developmental condition seen in the Cavalier King Charles Spaniel (CKCS), similar to Chiari type I malformation in humans. In COMS, an underdeveloped occipital bone results in a narrow foramen magnum and a shallow caudal fossa. This malformation can cause caudal displacement of the cerebellum, brainstem compression, hydrocephalus, and syringomyelia, however the soft tissue changes do not always correlate well with clinical signs. The aim of this study was to compare computed tomographic (CT) and radiographic measurements of the caudal skull with the neurologic status of the subjects.

Methods: Twenty-six CKCS dogs were imaged by computed tomography and radiography. Twenty-three dogs had a complete neurologic exam performed before imaging. Twenty dogs underwent Brainstem Auditory Evoked Response tests following imaging. Multiple measurements (linear and angular) of the caudal skull were made on acquired transverse and reconstructed mid-sagittal CT images, and on a rostrodorsal-caudoventral radiographic image. Measurements were compared both to the neurologic and BAER exams.

Results: The ratio of the height to width of the foramen magnum as measured on a transverse CT image was mildly predictive of an abnormal BAER test (p=0.0483). The odds ratio was 4.828 for every 0.05 cm increase in the ratio. The dorsum sellae to rostral aspect of the dorsal foramen magnum, and the dorsum sellae to caudal aspect of the foramen magnum, both as measured on a reconstructed mid-sagittal CT image, were individually predictive of abnormal outcome on the neurological exam (p=0.0144 and 0.0412, respectively). No relationship between radiographic measurements and neurologic status was found. Discussion/Conclusions: Preliminary results indicate that there are trends seen when comparing certain CT measurements to the neurologic status of CKCS dogs. These correlations are consistent with the expected skull malformation seen in COMS. Due to the large number of factors compared and the relatively small number of subjects, these results should be considered preliminary. Additional subjects will be required to substantiate these trends. Additionally, multivariate analysis would be possible with a larger number of subjects.

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UTILITY OF 3’-DEOXY-3’[18F] FLUOROTHYMIDINE-POSITRON EMISSION TOMOGRAPHY/COMPUTED TOMOGRAPHY FOR EVALUATING RESPONSE TO CYTOTOXIC CHEMOTHERAPY IN DOGS WITH NON-HODGKIN’S LYMPHOMA. Lawrence J1, Vanderhoek M2, Jeraj R2,3, Barbee D2, Wessel M1, Robat C1, Vail DM1,3. 1Department of Medical Sciences, School of Veterinary Medicine; Department of Medical Physics; and the 3Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin-Madison, Madison WI 53706. Introduction/Purpose: 3’-deoxy-3’[18F] fluorothymidine ([18F]FLT) was developed as a proliferation tracer. Imaging and measurement of proliferation with computed tomography (CT) and positron emission tomography (PET) provides a noninvasive tool for improved staging and monitoring of response to anti-cancer treatment. This prospective study evaluated [18F]FLT PET/CT for detection of early response, confirmation of post-treatment response and prediction of relapse in dogs with non-Hodgkin’s lymphoma (NHL). Methods: Nine dogs with NHL receiving 5 cycles of an investigational cytotoxic chemotherapy agent were included. All received baseline FLT-PET/CT imaging before chemotherapy. Imaging with FLT-PET/CT was to be repeated at various time points: group 1 (n=4), 5 days after initiation of chemotherapy and 3 weeks following the last chemotherapy administration; group 2 (n=5), prior to the 4th cycle of chemotherapy and 3 weeks following the last administration. Maximum standardized uptake values (SUV) for FLT were calculated using circular regions of interest with diameter 0.5 cm. Results: Eight of 9 dogs displayed initially high FLT uptake (mean SUV, 81.55). Maximum FLT SUV decreased significantly after chemotherapy (p < 0.05). Increased uptake preceded clinical and cytological evidence of relapse in 2 dogs. Discussion/Conclusions: FLT-PET/CT functional and anatomical imaging shows promise for the evaluation of response to cytotoxic chemotherapy in dogs with NHL and for predicting relapse prior to standard clinical and clinicopathologic conformation. Future studies will evaluate additional analytical methods of assessing FLT uptake, as well as correlations of FLT-PET/CT with histologic assessment of proliferative indices such as Ki67 and PCNA values.

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COMPARISON BETWEEN T1-WEIGHTED FLUID ATTENUATED INVERSION RECOVERY AND T1-WEIGHTED SPIN ECHO TO ASSESS CONSPICUITY OF BRAIN LESIONS. M. Lora-Michiels, A.F. Sato, A.S. Tidwell, A. Bilderback, P.A. March, D. Faissler. Tufts Cummings School of Veterinary Medicine, North Grafton, MA 01536. Introduction/Purpose: In humans, T1-weighted Fluid Attenuated Inversion Recovery (T1-weighted FLAIR) has been proposed to assess lesion enhancement following Gd-DTPA administration. One study reports superior conspicuity of T1-weighted FLAIRcompared to T1-weighted spin echo (T1-weighted SE) images at low magnetic field strengths. However, this effect has not been validated in veterinary patients. The purpose of this study is to evaluate differences in the contrast-to-noise ratio of brain lesions in dogs and cats imaged with T1-weighted FLAIR and T1-weighted SE in a 1.5T magnet before and after contrast administration.

Methods: Forty patients underwent routine brain MRI, which included pre- and post contrast T1-weighted SE (TR: 570ms ; TE: 9.7ms) and T1-weighted FLAIR (TR: 1800ms ; TE: 13ms ; TI: 860ms) pulse sequences. The order in which either SE or FLAIR pulse sequences was assigned was randomly determined. Regions of interest were drawn selecting the lesion, grey matter (GM), white matter (WM), cerebrospinal fluid (CSF) and background. The contrast to noise ratios (CNR) for lesion-WM, lesion-GM, lesion-CSF, GM-WM, WM-CSF were calculated pre-and post Gd-DTPA administration using the following formula: CNR= | tissue 1- tissue2 | / SD of the noise. Contrast to background ratios (CBK = lesion/SD noise) were calculated to evaluate differences in lesion conspicuity due to the effect of time in contrast distribution. A Wilcoxon sign rank test was used to detect differences between T1-weighted SE and T1-weighted FLAIR CNRs, and differences in CNR and CBK pre- and post contrast administration for each pulse sequence.

Results: MRI images from thirty-one dogs and nine cats with brain lesions were analyzed. The primary differentials for these lesions based on MRI included neoplasia (n= 24), meningo/encephalitis (n=8), stroke (n=6), and unspecified lesions (n=2). Both pre and post contrast CNR values for T1-weighted FLAIR were significantly higher (p<0.01) than those for T1-weighted sequence. Contrast administration did not significantly (p>0.05) affect CNR for GM-WM and lesion-WM for either pulse sequence. The order in which the pulse sequences were obtained following contrast administration did not affect (p>0.33) the differences in conspicuity to detect lesions among both sequences.

Discussion/Conclusions: The T1-weighted FLAIR pulse sequence provides superior conspicuity of brain lesions compared to the T1-weighted SE sequence both pre- and post contrast administration. Greater differentiation between GM and WM was detected with FLAIR pulse sequence than with SE. T1-weighted FLAIR may be an alternative to T1 weighted SE for routine brain MRI exams in a 1.5T magnet.

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MULTIPHASE TIME-RESOLVED CONTRAST-ENHANCED PORTAL MAGNETIC RESONANCE ANGIOGRAPHY IN SMALL ANIMALS. Mai W. Section of Radiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104. This study was made possible in part through the support of the AKC CANINE HEALTH FOUNDATION

Introduction/Purpose: Diagnostic imaging plays a central role in the diagnosis of anomalies of the portal vasculature in dogs and cats. Ultrasonography, conventional angiography, scintigraphy and computed tomographic angiography (CTA) are current methods used but all have their sets of limitations and/or invasiveness. Non-contrast-enhanced MRA has been used to diagnose porto-systemic shunts in dogs but acquisition is long and cumbersome, and sensitivity is low. Currently contrast-enhanced MRA (CE-MRA) has become a standard of care in human medicine for vascular imaging. The goal of this study is to demonstrate the feasibility of 3D time-resolved portal MRA in normal dogs and to illustrate its use in two animals suspected to have a porto-systemic shunt. Methods: Two clinically normal dogs and a dog and a cat with suspected congenital porto-systemic shunt were imaged using a 3D multiphase Fast Spoiled Gradient Recalled echo (3D FSPGR) CE-MRA sequence. The 3D volume for portal MRA was prescribed in a coronal oblique plane from the left hepatic vein confluence cranially to far caudal to the spleno-portal confluence. Four to five consecutive 3D-volumes were acquired in apnea starting immediately after the manual injection of 0.03 mmol/kg of gadolinium (rate 2-3ml/sec). Parallel imaging was used in two dogs to maximize coverage in the dorsal to ventral direction. Elliptical centric view-ordering of k-space was used to acquire the contrast sensitive data faster. Results: Each 3D-volume could be acquired in 12-13 s allowing for time-resolved imaging. In the clinically normal dogs, the celiac artery and its branches, the cranial mesenteric artery, the pre-hepatic portal vein and its tributaries and the intra-hepatic portal branches were easily identified. In one dog the dorsal to ventral coverage was sub-optimal resulting in some vessels being cut-off. With parallel imaging the entire dorsal to ventral direction could be covered by the 3D volume prescription. The method allowed to rule out or to confirm the suspicion of porto-systemic shunt in the two animals with clinical signs. In the animal with positive imaging diagnosis, the exact anatomy of the shunt was easily assessed with a combination of 3D-MRA images and sub-volume MIPs. Discussion/Conclusions: CE-MRA allowed time-resolved 3-D imaging of the entire arterial splanchic and portal venous system. No timing-bolus was required unlike with CTA and excellent depiction of the portal vascular anatomy was observed. With elliptical centric view-ordering of k-space, no overlap between the different vascular phases was seen. Parallel imaging allowed optimal coverage and imaging of all the vessels of interest. Reconstruction of 3D MIPs is much easier and faster than with CTA, and MRA does not use ionizing radiation or iodinated contrast medium. It is concluded that CE-MRA could be an alternative to CTA to diagnose porto-systemic shunts and other hepatic vascular anomalies in dogs.

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INITIAL EXPERIENCES WITH A 3T MR SYSTEM IN A VETERINARY HOSPITAL. T. Saveraid, S. Steward, R. Mandsager. College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, 55108.

Introduction/Purpose: Routine clinical imaging with 3T MR has been little described in veterinary medicine. Our veterinary medical center recently installed a 3T MR system (GE Signa HDx 3.0T). Prior to the purchase of the 3T MR system, concerns were raised from administrators, outside veterinary radiologists and clinicians about the clinical utility and wisdom of purchasing a 3T system. Specific patient safety and imaging concerns were overheating of small animal patients, increased scan duration secondary to exceeding specific absorption rate (SAR {W/kg}) limits, and impact of subcutaneous identification microchips on image quality. The impact on diagnostic image quality by the ID microchips as well as a smaller subset of the patient temperature outcomes and SAR results was recently reported.(1) This report summarizes our first six months of clinical experience with patient temperature changes and SAR delays. Methods: Approximately 328 clinical scans had been completed in the first six months of on-site 3T scanner operation. 97% of the scans have been of canine and feline patients. For a 90 day interval, immediate pre-MR and post-MR rectal temperatures were recorded on small animal patients. For a 120 day period, all SAR alerts from the system which resulted in temporary cessation of the scan were recorded. All scans were performed at the first level of SAR limit as set in the system software following Food and Drug Administration (FDA) human safety regulations. The body area imaged, the patient weight and the type of coil (Head, Extremity Knee, Neurovascular Array, Torso Array, or CTL Spine) used for each exam were recorded. Results: Pre-MR and post-MR temperatures were obtained on 127 patients. The mean temperature change was -1.8°C with a range of temperature change from -5.2°C to 1.0°C. Only 3.9% (5/127) patients had an increase in post-MR temperature. 96.1% (122/127) of the patients had a decrease in temperature. During the SAR study period, 8.2% (18/220) patients had SAR levels that led to temporary cessation of scanning. This subset had a mean temperature change of -2.3°C. The average length of SAR related delay was 21 seconds (range from 6 to 92 seconds). 5 of the 6 longest delays occurred while using the Head coil and 55.6% (5/9) Head coil exams had a SAR delay. The Extremity Knee coil had the lowest percentage of occurrence of SAR delay, 4.8% (3/62). Discussion/Conclusions: Clinical 3T MR scanning for small animal patients is performed without incident across a variety of sequence types. Patient overheating occurs uncommonly and the vast majority of patients decrease in temperature, likely secondary to general anesthesia. While SAR is four times greater at 3T than 1.5T, the impact of SAR delays on clinical scanning are infrequent and minimal. 1. T. Saveraid, et al. Who is afraid of 3T? Initial experiences with clinical MR scanning at 3T. (abstract) EVDI 2008 Annual Meeting. Svolvaer, Norway.

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CONTRAST-ENHANCED COMPUTED TOMOGRAPHY AND ULTRASONOGRAPHY AS PRE-OPERATIVE INDICATORS OF VASCULAR LUMINAL INVASION OF ADRENAL MASSES IN DOGS. R.M. Schultz, E.R. Wisner, E.G. Johnson, and J.S. MacLeod. Veterinary Medical Teaching Hospital, University of California, Davis, CA 95616-8747. Introduction/Purpose: The pre-operative assessment of adrenal masses is important as regional intraluminal vascular invasion increases the difficulty of surgical excision and concurrent nephrectomy yields a worse prognosis. The purpose of this study was to assess the utility of contrast-enhanced computed tomography (CECT) and ultrasonography (US) for preoperative adrenalectomy planning in dogs. Our hypothesis was that CECT would be comparable to US for the assessment of vascular luminal invasion by adrenal masses. Methods: The medical records of dogs with an adrenal mass that received a pre-operative CT and US were retrospectively reviewed. US was assessed by reviewing static images and written reports, whereas complete CT scan data was available and blindly reviewed. Vascular involvement was determined by surgery or necropsy and histology. Results: Fifteen dogs with 17 adrenal masses were included. 17 adrenal masses were identified on CECT while 16 were documented by US. Nine adrenal masses were determined to be non-invasive and all were correctly identified as non-invasive on both CECT and US. The remaining 8 masses were determined by surgery and/or histology to be invading one or more of the following vessels: phrenicoabdominal vein (n = 6), caudal vena cava (n = 5) and renal vein (n = 1). The presence of vascular invasion was determined correctly on CECT in 11/12 vessels. There was one dog in which the phrenicoabdominal vein was not identified. The presence of vascular invasion was determined correctly on US in 8/12 vessels. This included 2 of 6 with phrenicoabdominal vein invasion. In addition, one finding of caudal vena cava invasion and one of renal vein invasion was also recorded on US, but not surgically or histologically confirmed. 6/8 masses with associated vascular invasion had a histologic diagnosis and of these, all 6 were malignant. 4/4 histologically confirmed pheochromocytomas invaded the adjacent vasculature. Discussion/Conclusions: Given the small number of dogs in this retrospective study US and CECT appear similar for the pre-operative assessment of adrenal masses. Phrenicoabdominal vein invasion in 4 of 6 dogs may not have been reported due to the retrospective nature of this study or omissions on US reports. The false negative on CT was due to incomplete visualization of the phrenicoabdominal vein.

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DISTAL ABDOMINAL AORTA THROMBOSIS IN 4 DOGS DIAGNOSED BY CONTRAST-ENHANCED TIME-OF-FLIGHT MAGNETIC RESONANCE ANGIOGRAPHY. Sharpley J.L.1, Thode H.2, Sestina L.2, Park R.D.2, Monnet E.2, Kraft S.L.2 . 1Animal Surgical and Emergency Center, Los Angeles, CA. 90025. 2Department of Environmental and Radiological Sciences, Colorado State University, Fort Collins, CO. 80523.

Introduction/Purpose: Diagnosis of distal aortic thrombi has involved several methods of imaging including ultrasonography, computed tomography, x-ray angiography, nuclear scintigraphy, and magnetic resonance imaging (MRI). The purpose of this report is to describe how magnetic resonance angiography (MRA) aided in the diagnosis and treatment of four dogs with distal aortic thrombus formation.

Methods: Four dogs presented for evaluation of unilateral or bilateral hind limb lameness. Signalment, history, physical examination findings, diagnostic test results including complete blood count and blood chemistry panel were recorded. Results of other imaging methods including radiography and ultrasonography were also recorded. MRI of the abdomen was performed in all dogs including 3D contrast-enhanced time-of-flight MRA of the abdominal aorta. All dogs underwent exploratory laparotomy following the MRI studies.

Results: Three of the four dogs had abdominal ultrasound performed prior to MRI and MRA which identified an echogenic structure within the abdominal aorta. In all 4 dogs, a filling defect within the abdominal aorta consistent with a thrombus was identified using MRA. Three dimensional reconstruction of the angiogram allowed for visualization of the distal extent of the thrombus as well as the presence of collateral circulation. Surgical removal of the thrombus was attempted in all dogs.

Discussion/Conclusions: While less invasive and more readily available methods of imaging the abdominal aorta have been used to aid in the diagnosis of thrombosis, magnetic resonance angiography allows for better visualization and localization of a thrombus when surgical removal is considered as a possible treatment option.

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MAGNETIC RESONANCE IMAGING OF CANINE MULTIPLE MYELOMA OF THE

VERTEBRAL COLUMN. R. Monteiro, T.J. Trevail, A. Wessmann, M. Sullivan Division of Companion Animal Sciences, Faculty of Veterinary Medicine, University of Glasgow, Garscube Estate, Glasgow, Scotland, G61 1QH.

Introduction/Purpose: Multiple myeloma (MM) is the most common plasma cell tumor (PCT) of domestic animals. Radiographic and scintigraphic findings of canine PCT have been described but no report on the Magnetic Resonance Imaging (MRI) findings of MM in dogs exists to the authors’ knowledge. This study describes the MRI findings of vertebral MM in two dogs and suggests an MRI protocol for dogs with suspected PCTs of the vertebral column. Methods:

Survey spinal radiographs and MRI of the T3-L3 region were reviewed in two paraparetic dogs diagnosed with MM. MRI was performed in dorsal recumbency under general anesthesia using a 1.5T MRI scanner. T1-weighted fast spin echo (FSE), T2-weighted FSE and Short-T1 inversion recovery (STIR) sequences were obtained in the sagittal and transverse (T1 and T2) planes. T1-weighted FSE sequences were repeated after intravenous bolus injection of gadolinium.

Results:

Survey radiographs of the spine of both animals revealed only a solitary “punched-out” osteolytic vertebral lesion. These lesions were confirmed on MRI, with multiple additional lesions identified in both cases. Signal characteristics of all lesions compared with the spinal cord grey matter were isointense on T1 and T2-weighted images, markedly hyperintense on STIR images with moderate (case 1) or marked (case 2) homogenous contrast enhancement on T1-weighted images. All lesions were well marginated. Spinal cord compression was noted in one location in case 1 and in two locations in case 2. Discussion: The appearance of bone marrow, and hence vertebral bodies, can vary greatly on MRI depending on age. STIR sequences suppress fat signal, allowing differentiation of fat from abnormal vertebral tissue, thus aiding the recognition of further vertebral lesions. We suggest the following protocol for detection of vertebral involvement in MM: initial saggital STIR sequences of the entire spine with pre and post-contrast T1-weighted images for further evaluation of hyperintense lesions seen on STIR sequences. Transverse T1 and T2-weighted images at the site of lesion localization are recommended to evaluate spinal cord compression. Obtaining saggital STIR sequences of the whole spine reduces the risk of missed lesions. Conclusions: MRI is recommended for suspected PCTs where only a solitary vertebral lesion is detected on survey radiography to differentiate solitary PCTs from nonsecretory multiple myeloma. MRI provides a more sensitive technique for the staging of PCT, with the potential for earlier treatment and improved outcome.

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MAGIC ANGLE EFFECT IN NORMAL COLLATERAL LIGAMENTS OF THE DISTAL

INTERPHALANGEAL JOINT IN HORSES IMAGED WITH A HIGH-FIELD MAGNETIC RESONANCE IMAGING SYSTEM. M Werpy, CP Ho, CE Kawcak.

Introduction/Purpose: The purpose of this study was to evaluate the signal intensity of normal collateral ligaments of the DIP joint when imaged using short and long TE sequences and the influence of changes in angle on the ligaments relative to the main magnetic field. Methods:

Distal forelimb specimens in 4 skeletally mature horses were imaged using PD TSE, T1-weighted SPGR, T2*-weighted GRE, STIR and T2-weighted fast spin sequences with the limb in a neutral position, parallel to the main magnetic field, and with angulation of the limb (4, 8, 12, 16 and 20 degrees). The collateral ligaments were graded for degree of asymmetry and the mean signal intensity was measured. Following imaging the limbs were sectioned and grossly evaluated. The limbs were sectioned (5mm) with one collateral ligament cut in transverse plane and the other cut in frontal plane relative to the long axis to the ligament. The appearance and fiber pattern of the ligaments was grossly evaluated and correlated with the signal pattern on the various sequences to determine the possibility of magic angle effect based on fiber orientation. Results:

Magic angle effect can be identified in the collateral ligaments of the distal interphalangeal joint when imaged in a high field magnetic resonance imaging system with a horizontally oriented main magnetic field. This effect can be identified on short TE sequences and impacts the signal pattern and intensity of the ligaments at the level of the second phalanx with the limb in a neutral position and with angulation of the limb. In certain cases asymmetry was detected in the collateral ligaments with an angle as little as 4 degrees. The effect was more pronounced at 8, 12 and 16 degrees. Variation in fiber patterns can further impact the signal pattern in the ligaments. A T2-weighted fast spin echo sequence with a long TE allowed identification of magic angle effect. Evaluation of the gross specimens confirmed that the fibers in the collateral ligaments of the distal interphalangeal joint can align with the magic angle at the level of the second phalanx. Gross evaluation revealed different fiber orientations in the collateral ligaments at the level of the second phalanx with variations in the overall fiber pattern among the different specimens.

Discussion/Conclusions: Although T2-weighted FSE sequences may be insensitive to injury without increased fluid content, such as certain stages of degeneration and other types of desmopathy, it is an essential part of a musculoskeletal protocol to identify magic angle effect. Magic angle effect should be considered as a possible cause of an asymmetrical signal pattern, depending on the positioning of the limb and the sequences used for imaging, when evaluating the collateral ligaments of the distal interphalangeal joint when imaged on a high field MR system with a horizontally oriented main magnetic field. Due to the complex anatomy and variable fiber pattern of the collateral ligaments of the distal interphalangeal joint there are many aspects of magic angle effect which still need to be investigated to allow signal patterns that represent disease processes without increased fluid content to be confidently recognized.

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MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF NECROTIZING MENINGOENCEPHALITIS IN PUG DOGS. B.D. Young, J.M. Levine, G.T. Fosgate, K. Greer, S.J. Schatzberg. Texas A&M University, Texas, 77843 (Young, Levine, Fosgate, Greer). Introduction/Purpose: Necrotizing meningoencephalitis (NME) is an idiopathic, breed specific intracranial disease of young dogs and is believed to be invariably fatal. The goals of this study were to describe the common MRI findings of the brain of Pugs with histologically confirmed NME, examine the correlation of physical exam, MRI, and necropsy findings, and determine if MRI findings reflect duration of clinical signs prior to MRI or predict patient outcome. Methods: Pugs with antemortem MRI images and histologically confirmed NME were retrospectively selected. MRI lesions were characterized and compared to histologic lesions and physical exam findings. Regions of interest were hand drawn around the lesions, brains and lateral ventricles in every T2-weighted image. A DICOM-compatible program was used to estimate lesion burden by dividing the lesion voxel numbers by the brain parenchymal voxel numbers. Results: Eighteen dogs met the inclusion criteria. Most lesions were indistinctly marginated and 12/18 had mild parenchymal contrast enhancement. Lesions were most commonly seen in the prosencephalon (17/18), with parietal (16/18), temporal (16/18), and occipital (16/18) lobes most affected. In one dog, only brainstem lesions were seen. Lesions were present in both grey and white matter in all dogs and were always asymmetric. Falx shift was common (11/18), and three dogs had evidence of herniation. Leptomeningeal enhancement was present in 9/18 dogs. There was no correlation between physical exam, MRI, and necropsy findings. Higher lesion burden was correlated with longer time from disease onset to MRI (p = 0.045). Lesion burden did not correlate to survival time. Discussion/Conclusions: Several findings were common to NME in Pugs. While none were specific for NME, these findings in a young Pug with acute neurologic signs should increase confidence in a presumptive diagnosis.

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Saturday, October 25, 2008

7:15 am VRTOG Business Meeting 8:00 am Radiation Oncology Presidential Address – Dr. Deb Prescott 8:30 am Radiation Oncology Keynote Speaker “Altered Fractionation in Radiation Oncology” – Dr. Howard Thames, PhD 10:30 am Break 11:00 am Scientific Session 7: Radiation Oncology Moderator: TBD 11:00 am Use of Wet Gauze as Bolus Material for 6MV Photons: Impact of Wetness

Level and Air Gap - Benoit 11:12 am Palliative Radiation Therapy for Nasal Tumors: Retrospective Analysis of

Outcome and Prognostic Factors in 38 Dogs - Buchholz 11:24 am Long-Term Use of Vascular Access Ports in Dogs - Dominguez 11:36 am Accelerated Radiation Therapy With Concomitant Carboplatin for

Treatment of Feline Oral Squamous Cell Carcinoma - A Pilot Study - Fidel 11:48 am Rapamycin as a Radiation Sensitizer in Canine Melanoma Cell Lines -

Kent 12:00 pm Lunch 1:00 pm RO Business Meeting 2:00 pm Break 2:30 pm Scientific Session 8: Radiation Oncology, Continued Moderator: TBD 2:30 pm Impact of Tissue Inhomogeneities on Target Volume Dose in the Canine

Carpal and Tarsal Regions - Mayer 2:42 pm Use of a Petroleum Based Bolus for Photon Radiation Therapy of Distal

Extremities in Dogs - Mayer 2:54 pm Preoperative Radiotherapy in Canine and Feline Malignancies - North

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3:06 pm Monitoring Effects of Radiotherapy in Canine Tumors Using Dynamic

Contrast Enhanced MRI - Skogmo 3:18 pm Diffusion Weighted Imaging in Canine Sarcomas - Thrall 3:30 pm Irradiation Using Strontium-90 Applicator: Indications and Efficacy (30-

Years Experience) – Turrel 3:42 pm Radiation Therapy Planning Using CT and MR Images of the Brain - Lee 5:00 pm Adjourn 2008 ACVR Scientific Meeting

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USE OF WET GAUZE AS BOLUS MATERIAL FOR 6MV PHOTONS: IMPACT OF WETNESS LEVEL AND AIR GAP. J. Benoit, A. Pruitt, DE. Thrall. Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606. Introduction/Purpose: Despite the availability of commercial tissue-equivalent bolus material, wet cloth or gauze is still used in human and veterinary radiation oncology to provide more conformance to irregular contours. Use of wet gauze is based on water being tissue equivalent, and the standard to create dose build-up. The purpose of this study was to assess the effect of various gauze wetness levels on dose build up in comparison to Superflab® plastic bolus material, with and without air gaps, when used with 6MV photons. Methods: A parallel plate ion chamber with a thin membrane suited for measurements in the megavoltage build-up region was used. Five gauze sponge wetness levels were defined, ranging from dry to completely wet. Wet gauze was placed in a re-sealable zipper bag to prevent changes in hydration during the experiment. Various thicknesses of gauze of each wetness level were placed on top of the ionization chamber and ionization measured at various field sizes, with and without an air gaps between the gauze and chamber. Photons were generated from a 6MV accelerator. Ionization was normalized against ionization at dmax for Superflab®. Results: Completely hydrated gauze sponge provided less dose build than Superflab®, and this difference increased as hydration of the gauze decreased and as field size decreased. At Dmax with a 10 x 10 cm field, maximally hydrated gauze led to approximately 5% less ionization, and the lowest level of hydration was associated with over 10% less ionization than with Superflab®. The effect of an air gap between the bolus material and the ionization chamber was less than that of gauze hydration, and increased as field size decreased. Discussion/Conclusions: Wet gauze does not perform as effectively as commercial bolus, even when completely hydrated, especially when using small treatment fields. Wet gauze thickness may have to be increased to compensate for its decreased dose buildup capabilities. For large fields the surface dose perturbation due to an air gap under Superflab® is moderate and the bolus effectiveness in this situation is greater than when using a nominal thickness of wet gauze that conforms more precisely. Thus, Superflab® with an air gap may be more effective in producing dose build up than a fully hydrated gauze sponge without an air gap. These results indicate that care must be given to the selection of bolus material in patients where treatment of superficial skin layers is important.

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PALLIATIVE RADIATION THERAPY FOR NASAL TUMORS: RETROSPECTIVE ANALYSIS

OF OUTCOME AND PROGNOSTIC FACTORS IN 38 DOGS.

J. Buchholz1*, C. Leo1, A. Ebling2, R. Hagen2, C. Rohrer Bley1 1Section of Radiation Oncology and 2Section of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, Switzerland, CH-8057.

*Current affiliation: Cancer Treatment Unit, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803.

Introduction/Purpose:

External beam radiation therapy is the treatment of choice for nasal tumors. The main reason for treatment failure is local tumor recurrence. Median survival times with definitive radiation are about 1 year. The rationale of this study was to evaluate outcome and identify possible prognostic factors in dogs treated with a coarse fractionated radiation protocol administered with 6 MV photons, using CT-based 3-D-treatment planning. Methods: Dogs with histologically confirmed malignant nasal tumors, CT scans of the head for assessment of the extent of local disease, and a “palliative” radiation protocol were included in the study. Protocols used consisted of 3-4 8 Gy fractions on days 0, 7, (14), 21; 4-5 biweekly 6 Gy fractions or, for patients with a large amount of brain involvement, 10 daily 3 Gy fractions. The following prognostic factors were evaluated for significance: age, stage as determined by CT criteria (involvement of bone, cribriform plate, one vs. both nasal passages), Adams’ stage (dichotomized to stages 1 + 2 (stage 1modif) vs. stages 3 + 4 (stage 2modif)) (Adams 1998), histology, total dose of radiation (24 Gy vs. 30 Gy), overall treatment time, and epistaxis or facial deformity at presentation.

Results: Thirty-eight dogs were included in the study. The majority of the animals had carcinomas (n=25) or sarcomas (n=5); the remainder (n=8) had other tumors. Based on CT findings, the modified stage distribution resulted in 8 stage 1modif and 30 stage 2modif patients. Six dogs (16%) presented with loco-regional or distant metastasis. The most common presentations were epistaxis in 28 dogs (74%) and facial deformity including exophthalmus in 7 dogs (18%). 29% of all dogs were irradiated with a total dose of 24 Gy and 71% received 30 Gy. In all cases, resolution of clinical signs was reported. The median DFI for all patients was 10 months [95% CI 7.0-13.0 months]. For patients with stage 1modif the median DFI was 21.3 months [95% CI 10.7-32.1 months] and for stage 2modif, 8.5 months [95% CI 5.0-12.1 months] (p=0.0006). The median overall survival time was 10.1 months, [95% CI 8.6-11.5 months], with 18.2 [95% CI 9.5-26.9 months] and 8.6 months [95% CI 4.8-12.3 months] for stage 1modif and stage 2modif, respectively (p=0.0009). All patients died or were euthanized due to tumor related disease. Modified stage was found to be the only prognostic factor for outcome.


Given the rather short survival times, treatment times of a month or longer and considerable side effects from definitive treatment of nasal tumors, for older, polymorbid or more advanced disease patients, outcomes for alternative, coarse fractionated treatment protocols are comparably satisfying. Based on the results presented here, the recommendation for a carefully planned palliative approach should be considered in favor of some patients and particular client situations.

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LONG-TERM USE OF VASCULAR ACCESS PORTS IN DOGS. P.A. Dominguez, C.C. Warzee, L. Occhipinti, E.A. McNiel. Michigan State University, East Lansing, MI 48824.


The demand for permanent/long-term venous access in veterinary medicine has increased significantly in the last decade. Vascular access ports (VAPs) provide a quick and easy way to obtain blood samples and administer intravenous therapeutics and anesthetics while minimizing restraint, stress to the patient, and time. Complications associated with the use of VAPs in dogs are reported to include infection, thrombosis, seroma formation, port occlusion, port dislodgement or migration and hemorrhage. However, the numbers of dogs included in reports is relatively small and duration of use has been relatively short. Our objective was to contribute additional data regarding VAP use and prevalence of complications in dogs with cancer, particularly in association with longer-term placement.

Methods: The medical records of dogs implanted with vascular access ports for radiation and chemotherapy were retrospectively reviewed. All VAPs were implanted into the right jugular vein using a modified version of a previously described surgical technique. In addition to patient characteristics, VAP-associated complications were recorded. Reason for VAP removal and tip culture results were also recorded. Results: VAPs were placed in 42 dogs and maintained for a mean of 208 days (median = 175 days; range, 11-664 days). VAP tip location was confirmed in 23 of 42 dogs (54.8%): 11 at cranial vena cava, 9 at venous sinus, 1 at the right atrium, 1 at right jugular vein and 1 at caudal vena cava. VAPs were accessed for a mean of 21 times (range, 5-38). Seven of 42 dogs (16.7%) received concurrent radiation and chemotherapy. Post-operative seroma formation occurred in 10 dogs (23.8%), VAP occlusion in 3 dogs (7.1%), and port migration/ dislodgement in 6 dogs (14.3%). Nineteen dogs had their VAP removed: 10 because of owner request, 3 because of infection, 3 because of migration/dislodgement, 2 because of continued seroma formation and 1 because of thrombosis. Nine VAPs were cultured after removal, 5 of which resulted in positive cultures. Sixteen dogs still have a VAP in place (median follow-up = 332.5 days). Seven dogs died or were euthanized with a functioning VAP in place. Discussion/Conclusions: Removal of VAPs after completion of therapy may be unnecessary as the prevalence of complications associated with the long-term use of VAPs appears to be similar to those reported for short-term use in dogs. While undesirable, most complications associated with the use VAPs in dogs are inconsequential and of short duration.

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ACCELERATED RADIATION THERAPY WITH CONCOMITANT CARBOPLATIN FOR TREATMENT OF FELINE ORAL SQUAMOUS CELL CARCINOMA - A PILOT STUDY. J Fidel, R Houston, B Wheeler, C Tripp, J Bryan Veterinary Clinical Sciences, Washington State University, Pullman, WA, 99164-6610. Introduction/Purpose: Cats diagnosed with head or neck squamous cell carcinoma (SCC) will generally succumb to tumor within 2-6 months post diagnosis. All previous attempts at therapy have failed unless the tumor can be surgically removed. Our group has previously reported on the use of a 9 day accelerated radiation therapy protocol for oral SCC in cats. Although little toxicity was seen and results initially appeared promising, overall median survival for oral tumors was only 86 days (mean 173 days). We hypothesized that this same accelerated protocol delivered with concomitant carboplatin chemotherapy would improve tumor control without increasing toxicity to unreasonable levels, and might provide curative therapy for this tumor. The purpose of this study was to investigate the feasibility, toxicity and efficacy of this chemotherapy plus radiation protocol. Methods: All cats had histopathologic diagnosis of SCC and were staged with thoracic radiographs, lymph node aspiration, and tumor imaging (MR). Radiation treatments were given twice daily for 7 days in a 9 day period using 3.5 Gy fractions to a total of 49 Gy. Dosimetry was planned manually with the goal of incorporating the gross tumor volume, 1 cm margins, and draining lymph nodes in one field. Carboplatin was given IV immediately before the first or second radiation treatment, and repeated 4.5 -5 days later. The dose each time was 90 mg/m2 for total dose of 180 mg/m2 within the 9 day period. Carboplatin at full dose was also repeated at 1 month intervals in 4 of the cats. Results: Eight cats have been treated with tumors including 3 mandibular (1 schirrous), 2 lingual, 2 tonsillar, 1 cheek. Median age was 10.5 years. Acute reactions in all cats were grade 1 for skin, and 2 for the oral mucosa. Seven cats had feeding tubes placed and 4 were removed at 1 month post treatment. All but one cat responded to treatment. One cat experienced bone necrosis at 3.5 months post treatment and one cat appeared to have tongue fibrosis at 2 months post therapy. Median survival was 121 days (range 83-298 days), with a mean of 201 ± 46 days. Four cats are still alive and were censored from survival calculations. These cases are very similarly matched with cats treated with the radiation only protocol but the difference in survival was not significant (p= 0.31). Discussion/Conclusions: The treatment was well tolerated by all cats in the acute phase. Late reactions however may have been seen. The median survival has improved over radiation alone, but has not yet achieved statistical significance.

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RAPAMYCIN IS A RADIATION SENSITIZER IN CANINE MELANOMA CELL LINES. M.S. Kent, F. Ye. School of Veterinary Medicine, University of California. Davis, CA 95616. Introduction/Purpose: Malignant melanoma is thought to be more resistant to the effects of irradiation than many other cell types, requiring increased doses per fraction for effective treatment. Radiation sensitizers might allow for more traditional fractionation protocols to be used. We have previously shown that mTOR is present and active in canine melanoma, and treatment with rapamycin can inhibit the mTOR pathway. Our hypothesis is that treatment of canine melanoma cells with rapamycin and radiation will be more effective than either modality alone.

Methods: Proliferation assay: Two cell lines were plated and grown to near confluency. Treatment groups were: 1) untreated, 2) treated with 10nM rapamycin, 3) treated with radiation (4 or 12Gy), or 4) treated with rapamycin and radiation. Each 24hrs for 5 days cell were counted. Clonogenic assay: The same cell lines (with or without 10nM rapamycin treatment) were treated with increasing doses of radiation. Resulting colonies were counted. Non-parametric statistical analysis was used for all analyses with p<0.05 considered significant.

Results: Proliferation assay: There was a significant decrease in cell number with increasing doses of radiation. There was also a significant decrease in cell number with rapamycin treatment at each dose of radiation. Clonogenic Assay: There was a significant decrease in clonogenicity for each cell line at each dose of radiation between those cells treated with or without rapamycin.

Discussion/Conclusions: The results of this study suggest that rapamycin is a radiation sensitizer in canine melanoma. Decreased cellular proliferation is one mechanism of radiation sensitization by rapamycin.

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IMPACT OF TISSUE INHOMOGENEITIES ON TARGET VOLUME DOSE IN THE CANINE CARPAL AND TARSAL REGIONS. M.N. Mayer, H. Yoshikawa, N. Sidhu. University of Saskatchewan, SK, S7N 5B4. Introduction/Purpose: Although photon attenuation is independent of atomic number in the range of energies commonly used for veterinary radiation therapy, the higher electron density of bone tissue results in greater attenuation of a photon beam in bone tissue than in soft tissue. The presence of bone tissue within a patient treated with a parallel-opposed beam arrangement will result in a decrease in dose throughout the patient. The magnitude of this decrease depends in part on the amount of bone relative to soft tissue, which is high in the canine distal extremity compared to other anatomical sites. The purpose of this study was to compare the dose distribution achieved using treatment plans calculated without inhomogeneity correction to the dose distribution achieved when tissue inhomogeneities were taken into account, in the canine carpal and tarsal regions, for a cobalt therapy machine and a 6MV linear accelerator. Methods: We calculated the monitor units for a typical clinical distal extremity setup by two methods, using equally weighted, parallel opposed treatment fields. The first method was a computed tomographic-based computerized treatment plan, calculated with no inhomogeneity correction. The second method was a point dose calculation to the isocenter, using treatment depth measured at the isocenter. We then used our computerized planning system to perform inhomogeneity correction and assess the dose distribution achieved by these two methods when tissue inhomogeneities were taken into account. Results: The greatest difference between plans calculated with and without inhomogeneity correction was found in the minimum dose to the planning target volume (PTV), which was lower in plans calculated without inhomogeneity correction. The magnitude of the difference in minimum dose to the planning target volume was greater than 3% of prescribed dose for the 6MV linear accelerator and greater than 5% of prescribed dose for the cobalt therapy machine. The difference in minimum dose to the planning target volume was greater for a cobalt machine than a 6MV linear accelerator, and greater for point dose calculations than for computed tomographic-based plans. Discussion/Conclusions: The minimum doses to the PTV achieved without using inhomogeneity correction for the cobalt therapy machine would not meet the criteria for acceptable PTV coverage at our facility, which include coverage of the PTV with a minimum of 95% of the prescribed dose. For this reason, we now perform computed tomographic-based plans using inhomogeneity correction for distal extremities treated with the cobalt therapy machine. The difference in minimum dose to the PTV between plans with and without inhomogeneity correction was not as pronounced for the 6MV linear accelerator, and it is difficult to predict the clinical significance of this difference.

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USE OF A PETROLEUM BASED BOLUS FOR PHOTON RADIATION THERAPY OF DISTAL EXTREMITIES IN DOGS. M. N. Mayer, H. Yoshikawa, L. Moriarity, N. Sidhu. University of Saskatchewan, SK, S7N 5B4. Introduction/Purpose: While skin sparing is an advantage of megavoltage beams, in certain clinical situations the planning target volume includes the skin surface and a skin sparing effect is not desirable. A tissue equivalent material, termed build up bolus, is used in these situations to provide adequate absorbed dose at the surface of the skin. However, an irregular patient contour can lead to air gaps between the build up bolus and the skin surface, which may result in variability in radiation dose across the target volume. The shape of the canine distal hind extremity is irregular, and commercially available bolus materials do not conform well to this region. The purpose of this study was to assess the dose homogeneity achieved using a petroleum based bolus material, in combination with a commercially available sheet bolus, for radiation treatment of the canine tarsus. Methods: The petroleum based bolus formulation evaluated in this study was originally developed at a human cancer center for total body irradiation, and consisted of white petroleum jelly, microcrystalline wax, and glass beads. The ratio of petroleum jelly to wax in the human center formulation was modified to optimize conformability to the distal canine extremity. Central axis depth dose distribution in the bolus material was determined for a cobalt therapy machine and a 6MV linear accelerator using a Pinnacle3 treatment planning system. To assess dose uniformity achieved using a combination of bolus and Superflab, we evaluated clinical target volume dose in a canine tarsal region which was repeatedly positioned for treatment, simulating typical treatment setups in a clinic setting. Computed tomographic scans were performed after each setup. Dose distribution achieved with a cobalt therapy machine and a 6MV linear accelerator was assessed using Pinnacle3 software. Results: The mean percentage difference in absolute dose along the central axis between the bolus material and a simulated water phantom was 0.09% (95% CI, 0.07% to 0.10%), with a range of 0 to 0.19%, for the cobalt therapy machine, and 0.11% (95% CI, 0.08% to 0.14%), with a range of 0 to 0.33%, for the 6MV linear accelerator. All points within the clinical target volume received greater than 95% of the prescribed dose, and less than 107% of the prescribed dose, for each of the ten treatment setups with both treatment machines. Discussion/Conclusions: The use of a petroleum based bolus and Superflab provided clinically acceptable dose uniformity across the clinical target volume in the canine tarsal region. The petroleum based bolus is tissue equivalent, conforms well to the irregular contours of the canine extremity, retains its shape once positioned, and can be made in a veterinary radiation facility at a reasonable cost. The use of this petroleum based bolus could be extended to other areas of the body in which the patient contour is irregular and leads to air gaps between bolus material and the skin surface.

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PREOPERATIVE RADIOTHERAPY IN CANINE AND FELINE MALIGNANCIES.

S.M. North, H. L’Eplattenier, L. Findji. VRCC (Veterinary Referrals and Cancer Centre), Laindon, Essex, SS15 6TP England. Introduction/Purpose: Radiotherapy (RT) is traditionally used to eradicate microscopic disease, “cleaning up” dirty margins. Large tumours or those too deeply attached to be removed are considered inoperable. We report on the preoperative use of RT targeted to shrink tumour mass or sterilise margins facilitating surgery. Results are reported in 8 dogs & 2 cats. Methods: Experienced surgeons (HLE or LF) determined inoperability in 7 dogs & 1 cat, in 1 case (acanthomatous epulis, AE) surgery could have been performed (mandibulectomy) without prior RT but the client refused. 1 feline thymoma was evaluated for surgery only after RT. Canine tumour types included soft tissue sarcomas (STS) (2), haemangiosarcoma (HSA) on the ventral neck (1), thyroid carcinoma (1), malignant melanoma (MM) of the soft palate (1), oral squamous cell carcinoma (SCC) (1), oral fibrosarcoma (FSA) (1), AE (1). Feline tumours were both thymomas. All patients had confirmation of tumour type & appropriate staging prior to treatment. 3 cases had CT’s evaluating tumour extent & for RT planning (1 HSA, SCC and STS). For canine tumours a coarse fractionated protocol was used (900 cGy/fraction, 1/wk for 4 wks) using a 6MV Linac. Depending on location & size either parallel-opposed or single field plans were used. Dogs were assessed for response 2-3 weeks after treatment. RT protocol was chosen minimising number of treatments & acute effects of radiation that might delay surgery. Results: In 6 out of 7 dogs the tumours were considered operable, only 1 case was the tumour still inoperable. Reduction in size of the tumour facilitated surgery for patients with oral MM, FSA, SCC, facial FSA & thymoma. The AE patient had significant reduction in tumour size & had a partial mandibulectomy. Tumours made mobile as a result of RT (thyroid carcinoma, HSA & FSA) made dissection of the tumour possible. Acute side effects from RT were minimal: mild mucositis in dogs receiving oral radiation. Surgery was uneventful & no wound healing problems were reported. For feline thymomas either 1 or 2 treatments of 800cGy were given followed by thoracotomy. Discussion/Conclusions: We demonstrate the application of preoperative RT in a variety of tumours. The goal was to make inoperable tumours suitable for surgical excision by focusing treatment on reducing tumour size (lateral margins) & deep attachment in STS, HSA and thyroid carcinomas. All patients, except 1 (HSA) are currently alive & tumour-free (range 7-217 days post surgery).

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MONITORING EFFECTS OF RADIOTHERAPY IN CANINE TUMORS USING DYNAMIC CONTRAST ENHANCED MRI. H.K.Skogmo, Å.Søvik, D.R.Olsen, E. Malinen. Norwegian School of Veterinary Science and The Norwegian Radium Hospital, Oslo, Norway. Introduction/Purpose: To assess the clinical value of frequent dynamic contrast enhanced MRI (DCEMRI) during fractionated radiotherapy in a canine tumor model, and to evaluate the possible role of DCEMRI in biologically adapted radiotherapy. Methods: Six dogs with head and neck tumors were treated with fractionated conformal radiotherapy with 54 Gy given in 18 fractions. The tumors were investigated with T1- and T2-weighted MRI prior to each treatment fraction. The T1-weighted protocol included pre- and post-contrast imaging with a temporal resolution of 15 s over a time period of 15 min. The contrast agent was Magnevist® with a bolus dose of 0.4 ml/kg body weight. The images were analyzed using custom made software. Both the temporal and spatial enhancement pattern was investigated on a voxelwise level. The time intensity curves were subjected to pharmacokinetic analysis, providing physiological tumor parameters. The radiation dose dependence of both descriptive and pharmacokinetic parameters were investigated. The dogs were followed for the remaining of their lives, allowing for recording of disease-free interval and survival. Results: The characteristics of the individual enhancement patterns were persistent throughout the treatment course. The treatment affected the absolute level of enhancement for most tumors. However, the radiation-induced changes differed between the tumors, as seen for both the descriptive and pharmacokinetic parameters. The only consistent feature was a decline in the relative leakage rate of the contrast agent into the extravascular space. The number of patients was too scarce to make any firm conclusions on the predictive value of the MR images. The potential use of DCEMR images in adapted radiotherapy was explored by assuming a correlation between the contrast enhancement and the oxygenation. Discussion/Conclusions: DCEMRI for monitoring radiation-induced effects is feasible. Large intertumoral variations in contrast enhancement pattern may be expected.

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DIFFUSION WEIGHTED IMAGING IN CANINE SARCOMAS. DE Thrall1, BL Viglianti2, J MacFall2, 1North Carolina State University, Raleigh NC 27606, 2Duke University Medical Center, Durham NC 27710. Introduction/Purpose: Diffusion weighted imaging (DWI) is a magnetic resonance (MR) procedure used to assess Brownian motion of water. DWI is valuable for distinguishing acute stroke from other T2-hyperintense brain lesions causing acute signs, based on the highly restricted water diffusion that characterizes stroke-associated cytotoxic edema. As DWI is a functional imaging tool, it has also found use in humans in assessing water diffusion in solid tumors before and during treatment. Changes in DWI, most notably an increase in the water diffusion during treatment, are sometimes associated with improved outcome. Thus, DWI may have value as a predictor of outcome in canine tumors. The purpose of this study was to assess the feasibility of DWI in canine sarcomas and to characterize the pattern of change following treatment. Methods: Fourteen dogs with a soft tissue sarcoma entered in a prospective trial of thermal dose have been studied to date. Tumors received the same total thermal dose, using one of two fractionation prescriptions, in combination with fractionated radiation therapy comprised of 25 daily fractions of 2.25Gy. DWI was performed at 1.5 Tesla (Siemens Symphony, Malvern, PA) before treatment and during the last week of treatment using a half Fourier acquisition, diffusion-weighted, single shot turbo spin echo (HASTE) sequence. Diffusion images were acquired using two different gradient strengths (b values), from which an image of apparent diffusion coefficient (ADC) was computed, and quantified using ImageJ, a public domain Java image processing program. Initial ADC values and pattern of change were assessed. Results: HASTE DWI resulted in images in each dog wherein ADC values could be quantified. Pretreatment ADC values were typically in the range of 0.001-0.0015 mm2/sec while 4 dogs had higher values, between 0.0015-0.002 mm2/sec. At the end of treatment, the ADC had increased in 5 dogs, decreased in 6 dogs and was unchanged in 3 dogs. Results are consistent with canine sarcomas having relatively similar water diffusion prior to treatment, with variation in water diffusion as a function of treatment. Discussion/Conclusions: Assessing treatment efficacy early in the course provides an opportunity to tailor treatment to the patient. However, any method must be easy to perform, and have a relationship to outcome. HASTE diffusion imaging can be accomplished on most 1.5T units and is a quick sequence to acquire. As more animal cancer patients undergo MR imaging, inclusion of HASTE DWI will not be problematic. We found that HASTE DWI is feasible in canine sarcomas and that the pattern of change is variable between patients; another desirable characteristic of a predictive assay. Whether changes in DWI will be a robust predictor of outcome will require a larger study where all variables known to affect outcome can be considered along with changes in ADC. Supported in part by grant P01CA42745 from the Department of Health and Human Services.

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IRRADIATION USING STRONTIUM-90 APPLICATOR: INDICATIONS AND EFFICACY (30-YEARS EXPERIENCE). J. M. Turrel. Pacifica CA, 94044. Strontium-90 irradiation has been used since the early 1950’s to treat neolasms in human and veterinary medicine. Originally it was developed as an ophthalmic applicator for humans having non-neoplastic, benign or malignant ocular lesions. The active surface is concave and covered silver foil. Strontium-90 emits pure electron beam with a maximum energy of 2.27 MeV. Dose falloff is < 10% at 4 mm. Applicator activity varies widely and ranges from 40 to 140 mCi. Calculated surface dose ranges from 100 to 150 Gy resulting in treatment times varying from 2 to 5 minutes. Treatment is given as a single large dose resulting in tumor death within 14 to 20 days. Minimal side effects are observed although antiinflammatory or analgesic drugs may be needed. Since treatment itself is painless, physical restraint (cat bag, sand bags) was often adequate. Painful tumors required either mild sedation or general anesthesia. Tumors amenable for treatment are well defined and are 4 mm or less deep. Techniques to reduce tumor size are dependent on tumor type and location. Tumors with a high inflammatory component may shrink after parenteral methylprednisone and treatment is delayed for 2 to 10 days. Simple tumor debulking is feasible for exophytic masses or by expressing soft tumor tissue. Compression of the mass between a hard surface like a tongue depressor and the applicator can minimize tumor thickness. Treatment selection is best made on presumptive or cytologic examination. If the diagnosis is in question, a shave biopsy is preferred to punch biopsy. The punch can inject tumor cells deep into the tissue beyond the reach of the limits of the electrons. Subsequent inflammation after biopsy can increase tumor depth beyond the reach of the electron beam. Strontium-90 treatment can be combined with surgery, chemotherapy, hyperthermia or intralesional chemotherapy. Large cutaneous lesions such as multiple solar-induced SCC or SCC in situ can be time consuming and depending on the site strontium may be applied to some lesions and surgery done to others. On frequent treatment dilemma is SCC of the pinna of outdoor cats. If tumor numbers are low and the owner is inspired to make the cat live indoors, then Sr-90 is done. Otherwise, complete amputation of pinna is sometimes more realistic. Feline neoplasms treated are dermal SCC of eyelids, preauricular region, nasal planum, pinna, oral tumors including lingual (most were gently debulked), gingiva, hard and soft palates, tonsil. Bowen's lesions are sensitive regardless of size and location (oral and cutaneous). Hemangioma, hemangiosarcoma, fibrosarcoma and mast cell tumor fit the selection criteria. Canine, avian, equine, bovine, pocket pets, farm animals and exotic animals with superficial localized tumors can be effectively treated.

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RADIATION THERAPY PLANNING USING CT AND MR IMAGES OF THE BRAIN. N Lee, J.M. Poulson, C Azuma. Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA 01532.


Computed tomography (CT) based three-dimensional radiation therapy treatment planning systems are widely used as a standard system. CT provides excellent definition between structures with different electron densities due to the attenuation of x-rays by tissues as a function of atomic number, with fat, soft tissue, air, and bone attenuating x-rays differently. CT may not be useful for differentiating between structures with similar electron densities, including tumors, unless there is an obvious fat or air interface, or the tumor is enhanced after contrast administration. CT based systems can utilize the different electron densities to map the dose by regions of high electron density (bone) or low electron density (air) resulting in an accurate estimation of dose within heterogeneous tissues. Magnetic resonance (MR) techniques are based on the measurement of radio-frequency radiation resulting from transitions induced between nuclear spin states of tissue hydrogen atoms (protons) in the presence of a strong external magnetic field. Since MR imaging is based on the chemical characteristics of tissue rather than electron densities, MR provides better delineation of tumor extent and of adjacent critical structures. MR has become the gold standard for imaging tumors in the anatomical sites such as the brain and spinal cord, as well as for soft tissue regions. MR has been of limited use for radiation planning, the concern being that without the electron density information the dose estimation might not be as accurate as with CT based systems using heterogeneity correction. A recent study concluded that there was no clinical difference in heterogeneity-corrected versus uncorrected CT-based treatment plans in canine brain tumors, suggesting that the results validate the principle of using MR images directly for radiation planning of canine brain tumors.

The purpose of this study is to assess the dose distribution of MR image based radiotherapy planning for small animal brain tumors by comparing CT-based and MR-based plans for each patient. Our hypothesis is that there is no clinical difference in the dose distribution in the MR-based plans and the CT-based plans.

Methods: Three-dimensional conformal plans based on CT and MR were constructed using an XiO treatment planning system (CMS, St. Louis). Retrospective plans were made for twelve patients with brain tumors. Each patient had a CT scan and an MR scan, not more than 7 days apart, without any therapy between scans. Thirteen tumors were identified and each plan was developed. CT and MR plans were directly compared based on dose heterogeneity, target volume coverage, and dose-volume histograms.

Results: Preliminary results suggest that there is no clinical difference between 3D conformal plans developed using CT or MR images of brain tumors.

Discussion/Conclusions: It is predicted that there will be no significant difference in the dosimetric accuracy of radiotherapy planning using MR versus CT images for small animal brain tumors.

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American College of Veterinary Radiology

ACVR 2008 Conference Special Activities

Wednesday, October 22

San Antonio Ballroom Reception supported by

Orthopedic Foundation for Animals &

Universal Medical Systems, Inc. 6:30 – 7:30 p.m.

Special dedication to the memory of Dr. Myron “Mike” Bernstein

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