Abstracts

337

Suction Parameters for the Development of a Robotic

Endoscope for Traversing the Small IntestineRoberto Montane, Lukasz M. Kowalczyk, Anand Gupte, Carl D. Crane,Mihir S. WaghBackground: The upper GI tract and the colon are readily endoscopically accessiblebut the small intestine is relatively difficult to evaluate even with newer balloon andSpirus enteroscopes. This research focuses on using suction to design a self-advancing endoscope providing complete access into the small intestine. Aim: Todemonstrate the feasibility of utilizing suction as a means of locomotion within thesmall intestine and specifically, to determine the parameters that generate thegreatest amount of holding force while minimizing tissue damage. Methods:Prototype suction devices were designed in our laboratory. Segments of cadavericswine small intestine with mesentery were resected from the peritoneal cavity.Suction tips were advanced into the bowel lumen in a special setup and variousvacuum pressures applied. Test pieces of intestine were pulled against withincremental force until the suction cup disengaged from the intestinal wall or causedmucosal or mural damage. The amount of force needed to detach the suction tip fromthe intestine was recorded. The site of application of suction was inspected for trauma(tears or avulsions). For in-situ experiments, 2 suction devices (1 fixed tip and 1movable tip) were attached to the outside of the endoscope and advanced into thesmall intestine. By creating suction in the fixed tip, the endoscope was anchored andremained stationary while the movable tip was advanced two inches into the smallbowel. Suction was then applied to the extended movable tip to attach it to the distalmucosa. Suction on the fixed tip was then released and a puff of air instilled to detachit from the lumen. The movable tip with suction was then pulled back resulting inadvancement of the scope. These steps were repeated to advance the scope into thesmall bowel. Results: Vacuum pressures from 64 kPa - 85 kPa were applied to suctiontips. The measured force increased from 1.62 Newton (6 oz) to 3.89 Newton (14 oz)with increasing vacuum pressure. Even at high vacuum pressures no intestinal traumawas seen. A maximum force of 3.89 Newton could be attained from a single tip. In in-situ experiments the scope was advanced at least 25 cm into the small intestine withsequential suction application to the fixed and movable tip. Conclusions: This pilotstudy shows the feasibility of using suction for locomotion through the small intestinethat may ultimately allow the design of a self-advancing robotic endoscope. A highforce can be generated without causing mucosal tears or avulsion. Tip design will playa major role in the amount of force generated and future studies in live animals arewarranted.

338

The Clinical Utility of Tandem Auto-Flourescence (AFI) and

Narrow Band Imaging (NBI) in Patients with Barrett’s Esophagus

(BE)Ajay Bansal, Vikas Singh, Amit Rastogi, Sachin B. Wani, Mandeep Singh,April D. Higbee, Prateek SharmaBackground: Detection of neoplasia in BE pts may be facilitated by multi-modalityimaging that includes broad based (red-flag) techniques such as AFI followed bya focused examination with zoom NBI. Aim: To evaluate multi-modality imaging inBE pts using white light (WLE), AFI and NBI for the detection of neoplasia.Methods: Using a prototype multi-modality endoscope (GIF240, Olympus Inc),distal esophagus of BE pts (either undergoing surveillance or referred forendoscopic treatment of HGD/cancer) was evaluated with WLE, AFI and zoom NBIin a tandem fashion. Areas with purple fluorescence on AFI and an irregular/distorted pattern on zoom NBI were called abnormal. A ‘‘photomap’’ detailinglocations of ‘normal’ and ‘abnormal’ areas by each technique was noted usinga standardized form. Extent of BE was defined using the Prague C&M criteria. Inaddition to targeted biopsies from ‘abnormal’ areas, two representative biopsieswere also obtained from the ‘normal’ mucosa geographically distant from abnormalareas. All biopsies were collected in labeled separate containers and reviewed byblinded pathologists. Primary endpoint was detection of high-grade dysplasia/esophageal adenocarcinoma (HGD/EAC). For patient based analysis, a techniquewas credited with a positive outcome if a) an abnormal area was seen b) biopsyfrom the same area showed HGD/EAC. Results: 25 pts (7 referred for endoscopictherapy of HGD/EAC) with a mean age of 61 yrs (range: 51-84) were prospectivelyenrolled, all males and majority Caucasians. Mean C & M extents for BE were 3.5 cm(range: 0-6) and 5.4 cm (range: 1-15) respectively. 95% of the pts had a hiatus hernia(mean length: 3 cms (range: 0-9). Final histology was: cardiac type mucosa (nZ1),intestinal metaplasia (nZ11), low-grade dysplasia (nZ6) and HGD/EAC (nZ7).Five pts had visible lesions on WLE (3 nodules, 2 ulcers). AFI identified 23 abnormalareas in 11 pts and zoom NBI identified 19 abnormal areas in 12 pts. Patient basedanalysis showed: AFId(sensitivity 57%, specificity 61%, PPV 36%, NPV 79%) andzoom NBId(sensitivity 83%, specificity 63%, PPV 42%, NPV 92%). Area basedanalysis showed: AFId(sensitivity 69%, specificity 74%, PPV 46%, NPV 88%) andzoom NBId(sensitivity 75%, specificity 81%, PPV 47%, NPV 94%). Conclusion: Theresults of this prospective study demonstrate that the sensitivity of AFI for thedetection of HGD/EAC is sub-optimal even in an enriched BE population,irrespective of patient or area based analysis. This should dampen the enthusiasmfor AFI in its current form as a broad based (red flag) surface imaging technique.The high NPV of NBI should be confirmed in future randomized multi-center trials.

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339

Detection of Pre-Neoplastic Gastric Lesions in a High Risk

Chinese Cohort Using Endoscopic Autofluorescence Imaging

Followed By Narrow Band Imaging Versus Standard White Light

Endoscopy - Prospective Randomized Double Blind Crossover

StudyAndrea Rajnakova, Manuel Salto-Tellez, Ming Teh, Huak Y. Chan, JimmyB. SoBackground: Autofluorescence Imaging (AFI) and Narrow Band Imaging (NBI) arenew endoscopic techniques that may improve the detection of pre-neoplasticgastric mucosal changes and early gastric cancer. Objective: ProspectiveRandomized Double Blind Cross-Over Study using combined AFI and NBImodalities vs standard white light endoscopy (WLE) to improve the detection ofpre-neoplastic gastric lesions, such as intestinal metaplasia and mucosal atrophyand in high risk cohort. Patients: Informed consent was obtained from all subjectsenrolled prospectively in study. Sixty-five Chinese patients age O 50 years withdyspepsia were examined by both standard WLE and combined AFI/NBI techniquesconsecutively in a randomized sequence at the same setting by two independentendoscopists blinded for the results of different endoscopic modality used. In thecombined technique, the stomach was first examined by AFI followed by NBI. Allidentified lesions were documented in systematic order and biopsied. Lesional andtwo random biopsies from antrum, body, incisura and cardia were examined by twoexpert pathologists in a blinded fashion. Results: Of 65 patients recruited, onepatient was excluded for advanced gastric cancer diagnosed by both methods. Inremaing 64 patients, 228 lesions were identified and confirmed by histopathology,of which 146 (64%) lesions were identified by AFI/NBI technique and 82 (36%) byWLE. For the AFI/NBI technique 43/95 (45.3%) false positives and 20/51 (39.2%)were false negatives whereas for WLE it was 13/34 (38.2%) and 13/48 (27.1%)respectively. In total 30/63 (47.6%) subjects had intestinal metaplasia, of which 26(86.7%) were correctly identified by AFI/NBI technique (sen Z 83.9%, spec Z31.9%) and only 12 (40%) by WLE (sen Z 54.5, spec Z 71.0), p Z 0.004. Formucosal atrophy, it was 10/12 (83.3%, sen Z 58.8%, spec Z 65.1%) for AFI/NBI and4/12 (33.3%, sen Z 50.0%, spec Z 80.0%) for WLE, p Z 0.109. The overallsensitivity and PPV to identify any abnormal mucosal changes for AFI/NBI was 72.2%and 41.9% respectively compared to WLE 61.8% and 72.9% respectively. Randombiopsies analysis showed that from 11 subjects, 15/82 (18.3%) sites were missed byWLE compared to only 7/146 (4.8%) for AFI/NBI, p Z 0.001. For intestinalmetaplasia, from 8 subjects, 10 (12.2%) sites were missed by WLE compared to 3(2.1%) by AFI/NBI, p Z 0.002. There were no differences in the sites missedmucosal atrophy, from 6 subjects, by WLE (6.1%) and AFI/NBI (2.7%), p Z 0.211.Conclusion: This study confirms that AFI/NBI technique is increases the detectionof intestinal metaplasia which is a pre-malignant gastric lesion of clinicalsignificance.

340

Guided Esophageal Surveillance Biopsy with a Laser Marking

Optical Frequency Domain Imaging SystemMelissa J. Suter, Priyanka A. Jillella, Benjamin J. Vakoc, Brett E. Bouma,Norman S. Nishioka, Guillermo J. TearneyOptical coherence tomography (OCT) is a high-resolution cross-sectional imagingmodality that has been shown to accurately detect and diagnose esophagealpathology. We have previously demonstrated comprehensive microscopic screeningof the entire distal esophagus (~6 cm) using a second generation OCT technology,termed optical frequency domain imaging (OFDI), and a balloon catheter.Esophageal screening with OFDI opens up the possibility of significantly reducingsampling error by providing the capability to target high-risk biopsy sites. In orderto guide biopsy during esophageal surveillance, a method for registering neoplasticlesions identified by OFDI with endoscopy is required. We have developeda balloon catheter, guided biopsy platform that serves this purpose by firstscreening the distal esophagus with OFDI and then allowing the selection ofsuspect OFDI images based on previously established diagnostic criteria.Subsequently, with the balloon catheter still in place, these regions are markedusing a 300 mW, 1450 nm laser for 2-seconds. The marking process induceslocalized superficial thermal damage to the esophageal mucosa, which is visibleduring conventional endoscopy. To demonstrate the feasibility of the OFDI targetedbiopsy system, we have tested this method in swine in vivo. A total of 68 randomtargets where placed in the esophagus of 3 swine using the laser marking devicewith an exposure duration of 5 seconds. OFDI screening of the esophagus wassubsequently performed, the targets were located on the OFDI images, and laser-induced marks were placed on either side of the targets. Our results show that thetarget locations were correctly marked with an accuracy of 97.07% (95% CI: 99.7%,89.8) and that all laser-induced marks were visible by endoscopy. These resultsindicate that OFDI guided biopsy is feasible and may be utilized as an alternative toconventional random biopsy to decrease sampling errors during esophagealsurveillance.

lume 69, No. 5 : 2009 GASTROINTESTINAL ENDOSCOPY AB107