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What Is The Advantage Of MRI?

agnetic Resonance Imaging hasdeveloped into a powerful diag-

nostic imaging tool. Utilizing physicalproperties of magnetic fields and radiowaves, MRI can successfully generatehigh-quality images of human anatomy,displaying high tissue contrast and spa-tial resolution.

MRI is the superior modality for present-ing images that may demonstrate patho-logical changes in soft tissue. Bone dis-tortion is non-existent, thus making MRa commonly used procedure for brain,spine and musculoskeletal imaging. Inaddition, MR’s sensitivity to flowing

blood makes the technique particularlyeffective for cardiovascular imaging. As aresult, many steps are being taken to fur-ther develop MR Angiography in thedetection and localization of vascularmalformation.

MRI provides a safe and easy procedurefor the patient, with no ionizing radiation.This inherent safety combined with con-stantly improving MR imaging techniqueshave made magnetic resonance anextremely successful and popular modality.MRI will continue to develop asmore and more physicians utilize thetechnology for primary clinical screening.

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How Does MRI Work?

agnetic Resonance Imagingsystems are able to generate high

quality diagnostic images through theuse of a powerful magnetic field.

Hydrogen protons within the bodyalign with the magnetic field. By apply-ing short radio frequency (RF) pulsesto a specific anatomical slice, the pro-tons in the slice absorb energy at theresonant frequency causing them tospin perpendicular to the magneticfield. As the protons relax back intoalignment with the magnetic field, asignal is received by a RF coil that actsas an antennae. This signal is processed

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by a computer to produce diagnosticimages of the anatomical area of inter-est. Depending on the type of RF pulsesequence used, either T1 or T2 weight-

ed images are generated. Thesecontiguous thin slice images canbe obtained in various planesfor optimum clinical evaluation.

Is MRI Safe For My Patients?

RI is a convenient and safediagnostic procedure for

most patients. During the scan,the patient experiences nophysical sensations. There isonly a knocking sound made bythe gradients switching.

MRI is easy to operate like CT,but MRI does not utilize anyform of ionizing radiation. Thefact that there are no side or aftereffects associated with MRI fur-ther enhances its clinical accept-ance. MRI can eliminate the needfor other expensive or complicat-ed diagnostic procedures.

However, contraindications existfor some patients. The field inor near the magnet may fatallyinterfere with the operation ofdevices such as cardiac pace-makers. The static magneticfield may move or dislodge fer-

romagnetic materials within the body,such as intracranial aneurysm clips,which could cause life-threatening situ-ations. Patients with the followingshould also avoid MRI scans:

• Electromechanical aids, includingcochlear implants and spinalstimulators (Tens-unit)

• Inferior Vena Cava umbrellas• Implanted drug infusion devices• Metal workers (individuals who

might have an increased risk ofintra-ocular metallic objects)

• Shrapnel or bullet wounds

Newer non-metallic devices are nowmanufactured which would be safe inan MRI study. Patients should checkwith their physician.

MRI is not generally recommended forpregnant patients, as safety claims ofMR imaging during pregnancy have notyet been evaluated by the FDA. MRimaging may be used in pregnantwomen if other non-ionizing forms ofdiagnostic imaging are inadequate or ifthe examination provides importantinformation that would otherwiserequire exposure to ionizing radiation.

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Why Should I Refer My PatientsTo An AIRIS II?

he patient-oriented Hitachi AIRIS IIsystem provides a comfortable envi-

ronment during magnetic resonanceimaging examinations. It has an award-winning open gantry design that provideseasy access from all four sides and offersthe patient a comfortable non-claustro-phobic environment. The open designeasily accommodates not only claustro-phobic patients but also those who areanxious or large. For example, in manyprocedures, the patient’s head is outsideof the magnet. The large gantry openingprovides the opportunity to constantlyand directly attend to patients.

Popular features of the AIRIS II includethe comfortably padded patient table,which is power-driven in three direc-tions and aids in transferring patientsfrom hospital beds and wheelchairs.The table is extra wide and ultra thin,

T supporting large patients.Another popular feature is theAIRIS II Soft Sound® gradients,which are extremely quiet dur-ing the scan.

To ensure maximum comfort,a two-way intercom systemprovides communicationbetween the technologist andthe patient.

What Does The AIRIS IIProvide For Me Clinically?

he AIRIS II high performancepremium open MR system

has an open design that com-bines a 0.3T field strength andadvanced permanent magnet tech-nology for outstanding image qual-ity. In a clinical practice, the qualityof the images is extremely impor-tant to you and your patients.The AIRIS II high performanceopen MR system delivers trulyexceptional clinical imaging.

AIRIS II has an extremely fast

and powerful 15mT/m gradient systemthat provides thin slice imaging at smallFOV’s, and the extensive compliment ofRF coils provides high signal-to-noisefor the specific anatomical areas to beimaged. AIRIS II also has the addedthroughput with a state-of-the-art RISC-based workstation and easy-to-useOpenWindows™-based graphical userinterface.

MRI is used for all parts of the bodyand is effective in the clinical evaluationof many conditions.

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RI offers the best ofall imaging modalities

because of its superior con-trast differentiation betweenmuscle, fat, vessels, tendons,ligaments, cartilage, corticalbone and marrow bonespace. MRI displays excellentdelineation of soft tissue andbony tumors and is extremelyuseful in detecting avascularnecrosis of bone, particular-ly of the hip. High resolu-tion knee imaging tech-niques provide unparal-leled detail of the menisci,ligaments and cruciates.

MR imaging is very wellsuited for the evaluation ofligaments, muscle and bonyabnormalities of the shoul-der, without the need forpainful invasive procedures.MRI demonstrates similaradvantages in imaging othercomplex anatomy such asthe elbow, wrist, foot andankle due to its multi-pla-nar imaging capability, itssensitivity to soft tissue andbone disease processes andits ability to identifydislocations and fractures.

This T1-weighted coronal wrist image uses thinslice and small FOV to provide highly detailedanalysis of the triangular fibrocartilage, carpalbones, radius and ulna.

High intensity signal is depicted in thesupraspinatus area on this coronal oblique fastspin echo shoulder.

This 3mm FSE T2-weighted sagittal image ofthe knee demonstrates a high signal intensitytibial lesion and increased joint space fluid.

An Achilles tendon tear is demonstrated on thissagittal T1-weighted image of the ankle.

Orthopedic Imaging CapabilitiesM

RI of the brain hassurpassed CT in the

detection of diseaseprocesses due to its superi-or sensitivity and excellentpresentation of contrastbetween various anatomicalstructures. Compared toCT, MR studies of the pos-terior fossa are more well-defined because MRI is notsubject to bone artifactsthat obscure lesions, partic-ularly to those in the cere-bellar-pontine region.Complex imaging planesare possible which, for

example, allow direct imag-ing of the optic nerve andits tracts through theorbital apex and beyondthe optic chiasm.

MRI of the spine has longbeen the procedure recog-nized as yielding morediagnostic information forevaluation of primary ormetastatic tumors of thespinal cord. MR imaging ofother important anatomicalstructures of the spinal

This sagittal T1-weighted cervical spine imageprovides extended anatomical coverage frombrainstem to T-5.

This fast spin echo sagittal image of the lumbarspine demonstrates a large disc herniation atL5-S1.

A large enhancing lesion is visualized on thiscoronal post-contrast spin echo sequence.

This axial Fast FLAIR image offers detailedevaluation of white matter areas in the brainwith high T2-weighted contrast and suppressionof CSF.

Neurological Imaging CapabilitiesM

cord such as the nerve and nerve roots,neural foramina, ligaments and disc spacesis further enhanced by exceptional resolu-tion and contrast without boneartifacts which are common in CT spinalimaging.

Using orthogonal and oblique sliceplanes, along with various selections oftissue contrast, MR provides a highlyeffective alternative to X-ray myelogra-phy and the risks associated withintra-thecal contrast injections.

R angiography (MRA),the non-invasive MR

imaging method used toassess vascular conditions,has been proven effective inthe evaluation of vasculardisease without the discom-fort and the risk associatedwith using iodinated con-trast agents and cathetersused in conventionalangiography. It has beenfound to be instrumental inthe evaluation of acute vas-cular processes and acutehead trauma during whichtime the earliest and mostaccurate diagnosis is crucial.

A3DTOFmultiple slab image volume provides non-invasive visualization of intercranial vasculature.

This 2DTOF carotid MRA allows for evaluationof the carotid bifrications and the vertebralarteries in the neck.

This 2DTOF MRA provides a three dimensionalview of the venous flow from the sagittal sinus.

This 2DTOF femoral MRA demonstrates thefemoral bifrication using non-invasive MRimaging.

Vascular Imaging Capabilities

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Other Imaging CapabilitiesFacial/NeckMRI is also very effective inimaging other parts of thebody. Superb soft tissuedetail consistently demon-strated by MR imagingallows for enhanced evalua-tion of facial and neckstructures. Pre-surgical andpre-radiation treatmentplanning and follow-up areenhanced by MRI’s abilityto delineate anatomicalboundaries. In addition, itis easy to determine bothsize and extension oflesions in the face and neckarea. MRI also excels in theability to determine vascu-lar from non-vascularanatomy without the riskassociated with iodinatedcontrast agent use.

Abdomen/PelvisMRI of the liver offersunmatched sensitivity topathology compared to CTin the detection of primaryand metastatic liver tumors.Abdominal MR has beenimproved to provide fasterimaging techniques, allow-ing imaging within a singlebreathhold. MRI also pro-vides high resolution imag-

ing capability of the adrenals, kidneys,pancreas and spleen for diagnosis oftumors, infections and other vascularanomalies.

MRI of the pelvis and genitourinary sys-tem offers the advantages of improvedsoft tissue discrimination and absenceof bone artifacts. Also, MRI provides forsafe imaging of the reproductive regionof adults as well as children without theuse of ionizing radiation.

A sagittal fast spin echo pelvic image depictsabnormal signal intensities in the uterus.

Chest/CardiacChest anatomy inherently offers contrastwell suited for MR imaging from struc-tures such as fat, muscle, lung and flow-ing blood. Cardiac gating techniques pro-vide motion-free imaging for diagnosis ofvascular as well as non-vascular patholo-gy by capturing the images at the samepoint throughout the cardiac cycle. Avariation of this technique enables car-diac structures to be obtained in a cineformat for evaluation of the dynamics ofblood flow, cardiac valves, and cardiacwall motion.This ECG gated chest image provides extensive

visualization of the mediastinum void of flowrelated artifacts from the heart.

Dual-angle oblique capabili-ties along with pulsesequences designed toaccentuate flowing bloodallow imaging of the cardiacchambers in the long andshort axis. MRI is also ben-eficial for evaluation of thethymus and diseaseprocesses of the thoracicinlet due to the lack ofbone artifacts typically asso-ciated with CT scanning.

©Hitachi Medical Systems America, Inc. 1999All rights reserved999/15000/A2DE

Printed in U.S.A. MRI—

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iagn

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EdgeThe Hitachi AIRIS®II provides

the versatility needed to meeta demanding range of clinicalrequirements. It providescomfort for the patient whiledelivering consistently highquality images needed forcomprehensive diagnosis.And of course, the AIRIS IIis backed by Hitachi MedicalCorporation, a recognizedleader in diagnostic imagingtechnology.

OpenWindows is a trademark of Sun Microsystems, Inc.AIRIS II and SoftSound are registered trademarks of Hitachi Medical Systems America, Inc.