Su1422 Preliminary Feasibility Study Using a Novel Narrow Band Imaging System With Dual Focus Magnification Capability in Differentiating Colorectal Polyps

Abstract

Preliminary Feasibility Study Using a Novel Narrow Band Imaging System With Dual Focus Magnification Capability in Differentiating Colorectal Polyps Rajvinder Singh*, William Tam, Mahesh Jayanna, Nazree Nordeen Gastroenterology, Division of Medicine, Lyell McEwin Hospital, Adelaide, SA, Australia; Department of Medicine, University of Adelaide, Adelaide, SA, Australia Introduction: Advances in endoscopic imaging with real time diagnosis of colorectal polyps may lead to substantial time and cost savings and could potentially reduce complications associated with polypectomy and endoscopic resection. We prospectively assessed the utility of a novel Narrow Band Imaging (NBI) system with dual focus magnification (DF) in differentiating colorectal polyps. Methods: Consecutive patients undergoing a colonoscopy for any indication were invited to participate. All procedures were performed with a prototype 190 series Exera III NBI system (Olympus Co. Ltd, Japan) with DF capability. The NBI image has been brightened by 150% and the DF function enables magnification of upto 70X. Both are push button techniques and image enhancement with magnification occurs within 1-2 seconds. Histology of each polyp which was detected was predicted in real time with NBI-DF based on the modified Sano’s capillary network (cn) pattern; Type I: absent cn (hyperplastic polyp), Type II: cn present, surrounding mucosal glands (adenoma), Type IIIa: high density cn with turtousity and lack of uniformity (high grade dysplasia/ intramucosal cancer) and Type IIIb: nearly avascular cn (invasive cancer). This was followed by polypectomy, endoscopic or surgical resection. NBI-DF diagnosis was then compared to the final (blinded) histopathology results. The primary end point was the Sensitivity (Sn), Specificity (Sp), Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of neoplastic (Sano’s II, IIIa & IIIb) vs. non neoplastic polyps (Sano’s I). In addition, we also assessed a novel concept of ’endoscopic resectability’ of these polyps (Sano’s II/ IIIa vs. Sano’s I, IIIb). Results: A total of 44 polyps [mean size (range): 8.1 (3-40) mm] in 25 patients (17 males), with a mean age (range): 65.9 (43-83) years] have been evaluated to date. Twenty six polyps were located in the left colon (spleenic flexure and beyond) and 18 in the right. According to the Paris classification, 33 polyps were type Is, 6 Ip, 3 IIa and 2 IIa c. The Sn, Sp, PPV and NPV in differentiating neoplastic from non neoplastic polyps was 97%, 91%, 97% and 91% respectively. The Sn, Sp, PPV and NPV in differentiating endoscopic resectability was 97%, 91%, 97% and 91% respectively. Conclusion: In this preliminary feasibility study, NBI-DF permitted prediction of histology of colorectal polyps with high Sn, Sp, PPV and NPV. This approach may allow prompt decisions to be made if a polyp should be left in situ (Sano’s I), endoscopically resected (Sano’s II/IIIa) or biopsied and sent for further surgical intervention (Sano’s IIIb).