burning depth. In post-CSA patients, edema over a 650 μm depth range caused by freezingwas observed. Compared to RFA, CSA appeared to cause less overall architecture distortionin the tissue. Endoscopic OCT enables 3D real-time analysis over a large area of the treatedsite, potentially allowing assessment of treatment effectiveness using different ablation techno-logies. The correlation of these architectural changes to actual tissue destruction will befurther investigated. CONCLUSIONS: While endoscopic 3D-OCT does not possess the samemagnification or contrast as conventional histopathologic analysis, it is capable of visualizinglarge and deeper tissue volumes In Vivo. RFA demonstrates greater tissue architecturalchanges, but CSA shows treatment effects in deeper tissue structures. The ability to detecttissue structural changes following different ablation therapies makes 3D-OCT an ideal toolto assess the treated regions, help identify areas for retreatment, and guide refinements intreatment dosing.

T1214

Clinical Significance of Incidental Gastrointestinal FDG Uptake Found onPET/PET-CT Scans During Staging of Multiple MyelomaSomashekar G. Krishna, Shyam M. Dang, Brian T. Hughes, Dhaval H. Patel, FarshadAduli

Background: 2-(F)-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography-com-puted tomography (PET-CT) scans are non-invasive imaging modalities used to detect andfollow malignant tumors. FDG uptake is also seen in non-malignant process like granulomat-ous lesions, infective or inflammatory lesions, and physiologic sites with increased metabol-ism. Purpose: To evaluate the endoscopic and pathological findings of incidental gastrointesti-nal tract (GIT) FDG uptake on PET and PET-CT during staging of patients with multiplemyeloma. Methods: We conducted a retrospective review of PET and PET-CT scans forstaging of patients with multiple myeloma (January 2004 - December 2006). The incidenceof scans showing incidental GIT uptake, corresponding intensity [standard uptake value(SUV) based on lean body mass] and location was determined. The results of all endoscopicprocedures and histopathological findings were reviewed. Results: A total of 729 PET andPET-CT scans results were reviewed. Endoscopy was performed to verify FDG uptake in46 patients; endoscopic abnormalities were noted in 24 patients (52%), 18 of whom (39%)had biopsy proven disease. Lower gut diagnoses included tubular and/or tubulovillousadenoma (7 patients, SUV 5-17); plasmacytomas (SUV 10-14), adenocarcinoma (SUV ~7)and colitis (diffuse uptake), 2 patients each. Four patients had diverticulosis only (SUV 2-4). Upper gut involvement included esophagitis (3 patients, SUV 2-3), and gastricplasmacytoma (SUV 13.6), hiatal hernia (SUV 3.9) and Zenker's diverticulum (SUV 4.2),one patient each. The SUV for abnormal endoscopic findings ranged from of 2 to 17 (n =13, mean = 7.485) compared to normal endoscopic findings, range of 4-15 (n = 17, mean =6.812); p-value of 0.657. Conclusion: Among a homogenous population of patients withmultiple myeloma, incidental focal FDG uptake localized by PET or PET-CT within the GITappears to have clinical significance. Because intensity of FDG uptake was not predictive ofhistology, endoscopic workup is warranted in such patients.

T1215

Development of a Breath Test for the Evaluation of the Postprandial GastricAccommodation ProcessRafael Tojo, Laura Nieto, Enrique Dominguez-Munoz

Background: Gastric accommodation (GA) process provides a gastric reservoir allowing theingestion of a meal without increasing intragastric pressure or inducing postprandial symp-toms. GA is adapted to the properties of the meal and contributes to a correct gastricemptying of nutrients for a normal digestion process. Alteration of GA is accepted as a majorpathogenetic factor in functional dyspepsia. Methods to evaluate GA are invasive, non-physiological or inaccurate. Aim: To design a non-invasive, physiological method to evaluateGA based on the 13C-acetate breath test for gastric emptying of liquids. This GA breathtest is based on the hypothesis that two liquid meals of different volumes and the samecaloric load are emptied from the stomach at the same rate due to the GA process. Subjectsand methods: An experimental, open label, crossover study on 14 healthy volunteers (7men and 7 women, aged 20 - 25 years, mean age 22.6 + 0.8 years) was performed. Gastricemptying of four different liquid test meals containing 300Kcal each, and a volume of 200,400, 600 and 800 mL, respectively, was measured by the 13C-acetate breath test at fourdifferent days one-week apart. Breath samples were collected at 15min intervals for 180min,and analyzed by mass spectrometry. The half gastric emptying time (t1/2) for each test mealwas calculated and compared by ANOVA and Bonferroni test. Results: Gastric t1/2 was thesame for meals of 200, 400 and 600mL (68.4+11.0min, 64.5+8.4min, and 66.2+8.3min,respectively). On the contrary, 800mLmeals were emptied at a faster rate (t1/2=54.9+7.2min,p<0.05). Conclusions: The difference in gastric emptying rate (t1/2) of two meals of 600and 200mL as measured by 13C-acetate breath test is an adequate method to evaluate gastricaccommodation. In healthy subjects this difference is close to zero due to a normal GA. Ameal with a volume of 800mL exceeds the physiological GA capacity.

T1216

Vital Dye Enhanced Fluorescence Imaging of Esophageal and ColorectalNeoplasiaNadhi Thekkek, Timothy J. Muldoon, Alexandros D. Polydorides, Noam Harpaz, DipenMaru, Sharmila Anandasabapathy, Rebecca Richards-Kortum

Current endoscopic surveillance is limited in its ability to sample entire at-risk epithelium.High-resolution (HR) modalities such as confocal endomicroscopy afford an ‘optical biopsy'of epithelium, however these technologies image a small area (< 1mm). ‘Red flag' imagingof large surface areas is needed to identify mucosal changes warranting ‘optical biopsy.' Theobjective of this ex vivo study was to evaluate the feasibility of using widefield (WF) andHR fluorescence imaging with vital dye contrast to improve endoscopic evaluation in subjectswith gastrointestinal (GI) neoplasia. Methods: Proflavine (0.01%), a fluorescent dye that

S-513 AGA Abstracts

stains nuclei, was applied topically to fresh surgical resections. Two systems were used toimage; amultispectral microscope (WF resolution: 50-100μm) and a probe-basedmicroendo-scope (HR: 4-7μm). Proflavine excites at 450 nm and emits at 510 nm; corresponding filtersets were used. Images were compared to histopathologic gold-standard read by a GIpathologist. Results: WF fluorescence imaging of proflavine enhanced visualization of archi-tecture, such as glandular distortion and crowding associated with neoplastic progression.WFdifferences were further evaluatedwithHR imaging: neoplastic progressionwas associatedwith glandular heterogeneity and disorganization and nuclear crowding. In the esophagus- normal squamous, intestinal metaplasia and cancer were observed. In the colon - normalcolumnar, dysplasia, and cancer were observed (example shown in Fig. 1). Abnormalitiesvisible on WF images correlated to glandular and nuclear changes seen in HR images aswell as pathology. Conclusions: Imaging using topical proflavine shows promise in delineatingthe epithelial features of neoplasia. Enhanced glandular features seen using WF imagingcan guide HR probe placement for microscopic imaging and correlation with standardhistopathologic features. This preliminary work suggests that fluorescent endoscopic imagingusing a single dye provides a useful ‘bridge' between standard endoscopy and ‘optical biopsy'techniques. In Vivo evaluation is underway.

T1217

Endomicroscopy Can Readily Identify In Vivo Dysfunctional Cell Sheddingand Local Barrier Dysfunction in the Upper GI-Tract of Patients With Crohn'sDiseaseLee Guan Lim, Janina Patricia Neumann, Martin Goetz, Arthur Hoffman, Markus F.Neurath, Peter R. Galle, Alastair J. Watson, Ralf Kiesslich

Introduction: Increased epithelial cell shedding and epithelial gaps formation might play acrucial role in the intestinal barrier dysfunction of patients with Crohn's disease (CD). Aninitial study from our group reported an increased number of epithelial gaps within themacroscopically unaffected terminal ileum in CD which could only be identified usingconfocal laser endomicroscopy (Pentax, Japan). The aim of the study was to clarify whetherincreased gap formation is a local (terminal ileum) or systemic (involvement of the upperGI-tract) phenomenon. Primary outcome analysis was the total number of gaps withinunaffected gastric or duodenal mucosa.. Methods: Patients with known history of Crohn'sdisease and matched controls were recruited. Upper endoscopy with fluorescein aidedendomicroscopy (systemic application - 5ml; 10%) was performed and the mucosa of theantrum and duodenum were endomicroscopically imaged from the lumen to the laminapropria [z-stacks]. From each z-stack, 3 images with the most epithelial gaps were selectedfor interpretation. Total epithelial gaps (TEG) were the sum of confluent epithelial gaps(more than one cell-size width) and isolated epithelial gaps (one cell width). The amountof cell shedding was graded from 0 (none) to 8 (maximum). Luminal signal was gradedfrom 1 (black) to 6 (total white). Brighter luminal signal would imply leakage of fluoresceinacross epithelial gaps into the intestinal lumen and hence be a measure of local barrierfunction. Results: 6 patients with Crohn's disease and 4 controls were recruited. Patientswith CD showed significant higher amount of gaps, cell shedding and luminal signal comparedto controls (see table). Conclusion: Confocal laser endomicroscopy is the only imaging toolwhich enables the diagnosis of local barrier dysfunction and epithelial gap formation. Patientwith Crohn's disease without macroscopically affected upper GI-tract unequivocally showedendomicroscopically an increased amount of cell shedding, gaps and luminal fluoresceinleakage in the duodenum compared to normal controls. These findings imply that dysfunc-tional cell shedding is a systemic phenomenon of the small bowel and may play an importantrole in the pathogenesis of Crohn's disease.

T1218

Detection of Aberrant Crypt Foci in Patients at High-Risk for ColorectalCancer Using Confocal Laser EndomicroscopySanne Gulikers, Eveline Rondagh, Ann Driessen, Ad Masclee, Silvia Sanduleanu

Aberrant crypt foci (ACF) are considered putative precursors of neoplastic lesions and mightrepresent an early biomarker for colonic carcinogenesis. Previous studies in humans usinghigh-magnification chromoendoscopy showed large heterogeneity in the prevalence of ACF,resulting from technical difficulties in the histological confirmation. Confocal laserendomicroscopy (CLE) is a rapidly emerging endoscopy technique, which provides In Vivo

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