and to assess course of disease. The endoscopic assessement of MH using white light endoscopy comprise a broad range of macroscopic scores. The analysis of the mucosal microstructure using confocal endomicroscopy might give new insight into the process of MH during therapy and indicate more precisely MH. Aims: The aim was to investigate the utility of CLE for assessing in vivo the microscopical changings of the mucosa before and after start of infliximab (IFX) therapy in UC. CLE-morphological criteria (crypt number and architecture: distortion and crypt lumen; crypt erosions and ulcerations, goblet cell ratio, vascularity including leakage and cellular infiltrates) were evaluated. Secondly, to establish an endomicroscopical MH-score (eMHS). Materials & Methods: Consecutive active UC patients (Mayo6) were prospectively included and underwent colonoscopy with endomicroscopy before and after 3 IFX infusions. Based on the Mayo-score two groups i.e. therapy responders (Mayo3) and nonresponders (Mayo3) were defined. Further, a total of 300 random endomicrographs were analyzed in a blinded fashion by two experienced endoscopists, as follows: 100 micrographs from the responder group before and another 100 micrographs after 3 IFX infusions; 50 random confocal micrographs were analyzed from the non-responder group before and 50 after IFX therapy. The CLE features of the eMHS and their quantification was as follows: crypt number (absolute value), crypt distortion; crypt lesions), goblet cell ratio, vascularity, perivascular leakage, and cellular infiltrates. The score ranged from 0 to 9. Results: Post-IFX treatment, patients in the responder group showed an increase in crypt numbers and a decrease of the eMH score). The differences between these two parameters were found to be statistically significant within the responder group (P 0,0001 in the unpaired t test). In the non-responder group however the differences observed between the pre- and post-treatment scores did not reach the statistical significance level (P=0,3362, according to the Mann Whitney test). Mucosal healing was defined as eMH score 0. Endomicroscopic residual activity -not visible using white light endoscopy- ranged from eMH score 0-3 and consisted mostly in enlarged crypt lumen, leakage or hypervascularity. Conclusions: The new CLE classification system showed excellent accuracy with the therapy response assessed by clinical and endoscopic Mayoscore. Furthermore, microscopic aspects allow a more precise assessment of MH. CLE can accurately assess MH in vivo based on the newly developed and statistically validated eMH-classification system for UC. 1136 In Vivo Endoscope-Based Confocal Laser Endomicroscopy (eCLE) Improves Detection of Unlocalized Barrett’s Esophagus- Related Neoplasia Over High Resolution White Light Endoscopy: an International Multicenter Randomized Controlled Trial Marcia I. Canto* 1 , Sharmila Anandasabapathy 2 , William R. Brugge 3 , Gary W. Falk 4 , Kerry B. Dunbar 5 , Kevin E. Woods 3 , Jose Antonio N . Almario 1 , Ursula Schell 6 , Martin Goetz 6 , Ralf Kiesslich 6 1 Medicine, Gastroenterology, Johns Hopkins Medical Institutions, Baltimore, MD; 2 Gastroenterology, Mount Sinai School of Medicine, New York, NY; 3 Gastroenterology, Massachusetts General Hospital, Boston, MA; 4 Gastroenterology, University of Pennsylavnia, Philadelphia, PA; 5 Gastroenterology, VA North Texas Health Care System, Dallas, TX; 6 Gastroenterology, University of Mainz, Mainz, Germany Confocal laser endomicroscopy (CLE) may increase the detection of endoscopically-inapparent Barrett’s esophagus (BE) high grade dysplasia and early adenocarcinoma (neoplasia) compared to standard endoscopy. However, the role of endoscope-based CLE (eCLE) for prediction of BE neoplasia compared to high resolution endoscopy (HRE) is unknown. Aim: To compare the diagnostic yield, performance characteristics, and clinical impact of HRE+eCLE followed by targeted biopsy (TB) with HRE alone with TB and random biopsy (RB) for detection of BE neoplasia. Methods: 5 centers participated in this international, multicenter double-blind randomized trial. Participating site investigators from the all sites had baseline eCLE experience of  25 cases and passed a test for interpretation of esophageal eCLE images. Patients with proven BE 1-10cm in length were stratified by indication for endoscopy (routine surveillance or suspected neoplasia) then randomized to either HRE alone (Group A) or HRE + eCLE (Group B) using a 1:1 ratio. Patients with known localized neoplasia, esophageal lesion  2cm, prior ablation, or fluorescein-allergy were excluded. In Group A patients, HRE with TB of lesions followed by a standard RB protocol was performed. In Group B patients, HRE followed by fluorescein-aided eCLE with TB of endoscopic lesions and flat BE was performed. Before and after eCLE, a diagnosis was determined for each imaging site and a plan (do nothing, biopsy, or EMR) was recorded. After eCLE, EMR and/or RB protocol were performed. Biopsies were also taken for calculation of test characteristics during and after eCLE. Biopsies were interpreted blindly by 2 experienced pathologists. Results: Among 200 patients enrolled, 178 were evaluable at time of analysis (median age 62.6 years, 75% men, mean BE length was 2.9cm). 44 patients had suspected neoplasia, 134 were undergoing routine surveillance (final neoplasia prevalence 23% and 3.7%, respectively). 3 of the endoscopists had performed  75 eCLE cases, 2 were less experienced. 46 lesions in 33 patients were detected by HRE. Using a per biopsy analysis, the overall diagnostic yield for neoplasia (45.6% vs. 8.8%, p  0.0001) was 5.2-fold greater using eCLE, despite fewer biopsies obtained. The difference in diagnostic yield was primarily in patients with unlocalized neoplasia (59.5% vs. 12.7%, p 0.0001, 5.2-fold difference). Using a per patient analysis, HRE + eCLE led to 4-fold increase in diagnostic yield for BE neoplasia (79.3% vs. 20%, p0.0001). In 26 Group B lesions, eCLE changed the HRE diagnosis to a correct one in 15 (53.6%) and correctly changed the treatment plan in 9 (34.6%). CONCLUSION: Compared to HRE with RB, HRE+eCLE+TB improved detection of BE neoplasia with significantly fewer biopsies. eCLE led to greater sensitivity for diagnosis of neoplasia compared to HRE alone and impacts in vivo decision-making. Table. Performance Characteristics for Detection of Barrett’s Esophagus- Related Neoplasia (Per Biopsy Analysis n769) Group A HRE Alone Group B HRE  eCLE Sensitivity (%) 36.0 75.0 Specificity (%) 96.2 93.8 Positive predictive value (%) 37.5 72.6 Negative predictive value (%) 95.9 94.8 Accuracy(%) 92.6 90.9 1137 Multicenter, Randomized Controlled Trial of Confocal Laser Endomicroscopy Assessment of Residual Neoplasia After Mucosal Ablation or Resection of Gastrointestinal Neoplasia in Barrett’s Esophagus (Clean Margin Trial) Michael B. Wallace* 1 , Julia Crook 1 , Michael D. Saunders 3 , Laurence Lovat 2 , Emmanuel Coron 5 , Irving Waxman 4 , Prateek Sharma 6 , Joo HA Hwang 3 , Matthew R. Banks 2 , Mathieu De Preville 5 , Jean Paul Galmiche 5 , Vani J. Konda 4 , Nancy Diehl 1 , Herbert C. Wolfsen 1 1 Mayo Clinic, Jacksonville, FL; 2 University College London, London, United Kingdom; 3 University of Washington, Seattle, WA; 4 University of Chicago, Chicago, IL; 5 CHU Nantes, Nantes, France; 6 University of Kansas, Kansas City, MO Background: Endoscopic ablation has recently become the standard of care for high-grade dysplasia in Barrett’s esophagus (BE). The treatment endpoint, eradication of all glandular mucosa in the distal esophagus, cannot be reliably determined at endoscopy. The aim of this study was to assess if use of probe- based Confocal Laser Endomicroscopy (pCLE) in this setting could aid in more accurate determination of the presence of BE and guide continued ablation in real-time. Methods: Consenting patients were randomized to follow up of previous ablation with high definition white light (HDWL) endoscopy or HDWL plus pCLE. Treatment was based on whether the endoscopist suspected residual BE. In the HDWL+pCLE arm, a suspicion of BE (defined as endoscopic appearance of columnar lined esophagus; including intestinal or gastric metaplasia in the tubular esophagus) based on HDWL had to be confirmed with pCLE for treatment to proceed. Biopsy was performed immediately after imaging and patients had a follow-up procedure 3 months later. The primary outcome was the proportion of “optimally treated” patients defined as those with residual BE who were treated and had complete ablation, plus those without BE who were not treated and had no evidence of disease at follow-up. The original target sample size of 270 patients. Results: The study was halted based on a priori criteria at the planned interim analysis. This was based on (i) a much lower than expected proportion of patients with optimal treatment per protocol: 30% rather than the originally assumed 70 to 85% (ii) the higher than expected proportion of patients who were withdrawn after being consented and randomized, and (iii) the criteria for futility was met with conditional power estimated to be less than 20% (using updated assumptions).One hundred sixty- four patients were randomized (82 to each arm). Among the 119 patients with follow-up, there was no difference in the proportion of patients achieving optimal outcomes in the two groups (15/57, 26% for HDWL, 17/62, 27% with HDWL+pCLE). Other outcomes including over-treatment, under-treatment and findings at follow-up were similar. Conclusions: This study yields no evidence that the addition of pCLE to HDWL imaging for detection of residual Barrett’s esophagus or dysplasia can provide improved treatment. However the study was limited due to high rate of residual Barrett’s at follow up exam which implied that most patients in the study required retreatment. The way in which pCLE could be used to guide treatment was restricted since the main potential application is to distinguish residual BE when there in endoscopic uncertainty. Thus further evaluation of this imaging modality is needed to understand its utility in guiding continued ablation in this setting. Abstracts www.giejournal.org Volume 75, No. 4S : 2012 GASTROINTESTINAL ENDOSCOPY AB174