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sTu1185

Three-Dimensional Optical Coherence Tomography on Endoscopic MucosalResection Specimens Confirms Identification of Malignant From MetaplasticLesions in Patients With Barrett's EsophagusHsiang-Chieh Lee, Chao Zhou, Tsung-Han Tsai, Tejas Kirtane, Yuankai K. Tao, Osman O.Ahsen, Desmond C. Adler, Joseph M. Schmitt, Qin Huang, James G. Fujimoto, HiroshiMashimo

BACKGROUND/AIMS: Endoscopic mucosal resection (EMR) has been an effective methodto assess patients with esophageal nodules arising in Barrett's esophagus (BE). OpticalCoherence Tomography (OCT) enables real-time, three-dimensional (3D) imaging of tissuemicrostructure, with resolution approaching histology and can be used to evaluate patholo-gical features both In Vivo and within EMR specimens. In comparison, the latter is difficultto assess on confocal endoscopy which depends on In Vivo fluorescein to achieve optimalimages . METHODS: A prototype OCT imaging system was developed in collaboration withthe LightLab imaging Inc., providing images with an axial resolution of ~5um in tissue and~15um along the transverse dimension. The OCT system has an axial scanning rate of~59kHz and the system sensitivity is 103dB. The in-house developed fiberoptic imagingprobe (2.5mm in diameter) can pass through the working channel of the endoscope. A 3D-OCT dataset covering an imaging area of 20 mm x 8 mm x 2 mm can be acquired in 20s.Standard EMR was performed on 12 patients using Duette (Cook Medical, Inc.). Twenty-four EMR specimens, including 9 benign, 6 BE, 2 BE with low-grade dysplasia, 1 BE withhigh grade dysplasia, and 6 early adenocarcinomas, were subsequently imaged with 3D-OCT and sent for standard H&E histology. Imaging features identified in the OCT imageswere then compared with matching histology. RESULTS: Cross-sectional and en face imagescould be reconstructed from the 3D-OCT dataset. Cross-sectional OCT image showed featuresmatching with the corresponding histology. BE glands were observed at regions over thelamina propria layer while both the lamina propria layer and the muscular mucosa werepreserved in 87% of OCT imaging dataset. En face OCT highlighted the distribution of theglandular structures in Barrett's esophagus and allowed quantification of BE gland density.In lesions with intramucosal and invasive adenocarcinoma, the muscular mucosa layer wasless distinct or lost in the OCT images. This may be due to the destruction of tissuearchitecture or the thickened mucosa from the tumor. No lamina propria layer is identifiedin the datasets of 6 early adenocarcinomas. In addition, the shape and the distribution ofthe glandular structures were irregular compared to those of the BE glands. These distinctivepatterns associated with adenocarcinoma were observed in both cross-sectional and en faceOCT images. CONCLUSIONS: We demonstrated 3D-OCT images of EMR specimens ofhuman esophagus ranging from benign nodules, BE with LGD, BE with HGD to adenocarcin-oma. These studies comparing 3D-OCT images with histology are promising in improvingIn Vivo evaluation of esophageal nodules in the future. ACKNOWLEDGEMENT: NIH 5R01-CA075289-14 and AFOSR FA9550-07-1-0101.

Tu1186

Reversibility of Optical-Cleared Porcine Ileal Specimens Enables Integration of3-Dimensional Microscopy With the Standard H&E Tissue AnalysisYuan-An Liu, Shih-Hua Lee, Yun Chen, Shiue-Cheng Tang

Background & Aims: Optical clearing reduces random scattering as light travels across anopaque tissue such as the endoscopic biopsy. We have previously combined optical clearingwith confocal microscopy to develop a microtome-free method for 3-dimensional (3D)visualization of intestinal tissues with subcellular-level resolution (Fu et al., Gastroenterology,137:p453-463, 2009). Because optical clearing is reversible and the procedure of confocalimaging is noninvasive to the specimen, we aimed to use 3D microscopy as an add-on priorto the standard H&E procedure for tissue examination. Methods: Paraformaldehyde-fixedporcine ileal specimens were labeled with nuclear and membrane fluorescent dyes beforebeing immersed in the optical-clearing solution FocusClear (US Patent 6472216) for 3Dconfocal microscopy. Afterwards, optical clearing was reversed by washing the tissues withsaline. The specimens were subsequently processed with the standard H&E procedure.Results: Using Peyer's patches as the landmark, we observed matched tissue informationbetween the 3D confocal and standard H&E micrographs. Notably, 3D image acquisitiongenerated a continuous flow of information to supplement the H&E micrographs for anintegral visualization of the tissue structure. Conclusion: Incorporation of 3D microscopyprior to the H&E procedure adds connected 3D views to the robust, yet limited, 2-dimen-sional analysis of the gastrointestinal tissues.

S-762AGA Abstracts

Correlation between the ileal tissue map, 3D projection of the area of interest, and H&Emicrograph of the microstructure. Dimensions of the 3D projection: 326 X 326 X 105(depth) micrometers.

Tu1187

Safety of Endoscopic Cystgastrostomy in Patients With Gastric VaricesNitin Kumar, Christopher C. Thompson

Background: Pseudocysts are a common complication of pancreatitis with an incidence ashigh as 20-25%. Internal drainage via endoscopic cystgastrostomy (ECG) is an increasinglyemployed alternative to percutaneous or surgical drainage. The most worrisome complicationof ECG is uncontrollable hemorrhage. Additionally, patients with pseudocysts have a highrate of gastric varices (GV), with prevalence of 24% in one series, and some reports in theliterature have specified that GV are a contraindication to ECG. Aim: To determine thesafety of ECG in patients with confirmed GV on esophagogastroduodenoscopy (EGD) orendoscopic ultrasound (EUS). Methods: We retrospectively studied patients referred forECG for drainage of pancreatic fluid collection or necrosectomy of walled-off pancreaticnecrosis (WOPN) to determine which patients had GV confirmed on EGD and EUS. Allpatients with confirmed GV who underwent ECG are included in this series. Results: 6patients with confirmed GV, median age 53.5 (27-86), 3M+3F, were included. Cyst, GV, andECG characteristics are shown in Table 1. All patients had endoscopic video documentation ofGV. EUS was used in all cases to confirm lack of significant vascular structures within theneedle path during ECG. 19-gauge ultrasound needle was used to enter the cyst via transgast-ric approach in all cases; needle-knife was used to enter the cyst with Endocut settings incase 3 (Table 1). 5 patients underwent dilation of the cystgastrostomy site with balloon toa mean 18.6 ±1.0 mm (15-20mm); 1 patient had balloon dilation to 6mm. 4/6 cysts wereentered with a gastroscope and three of these patients underwent endoscopic necrosectomy.All patients had follow-up hematocrit within 10 days. There were no bleeding events orother complications during this period in any patients. In addition to finding of GV on EUSin all patients, 2 patients had bridging GV through the cyst cavity and 2 patients had GValong the cyst wall overlying the stomach on endoscopic cyst evaluation. On follow-up cystendoscopy, 2 patients were found to have ulcerations overlying the GV in the cyst cavity.Conclusions: Our experience in patients with GV suggests that ECG can be performedsafely with some modifications. We endorse endoscopic examination of the stomach withuse of EUS and color Doppler to guide needle insertion. GV must be kept under visualizationduring stent insertion and a guidewire used given the risk of vascular injury during stentplacement and subsequent removal. Additionally, when using pigtail stents, special caremust be used to avoid hooking the stent around a bridging varix. Given our encounterswith ulcerations overlying GV within the cyst cavity, we recommend that patients with GVwho undergo ECG be placed on PPI.Table 1: Cyst, GV, and ECG characteristics