Clinical Significance of Image-Enhanced Endoscopy, Autofluorescence Imaging (AFI) Observations in Differentiation Between Colonic Neoplastic Lesions and Non-Neoplastic Lesions

Abstract

Background/Objectives: Some flat type colonic lesions could be missed with conventional white light endoscopy. In the DDW 2007 meeting, we demonstrated the benefit of Autofluorescence Imaging (AFI) observation, which makes detection of neoplastic lesions easier. The purpose of the present study was to investigate feasibility of differentiation between neoplastic and non-neoplastic lesions using AFI system. Subjects/Method: Investigations were made on 155 cases with 190 lesions for which endoscopic or surgical resections had been performed after white light and AFI observations at our department during the period from September 2005 to November 2007. The intensity of the magenta color of the lesion observed with the AFI system was graded into 4 levels from Grade 0 to 3, and compared with the final pathological diagnosis. Furthermore, the possibility of making differential diagnoses between serrated adenomas and hyperplastic polyps, for which conventional endoscopic differentiations are difficult, was investigated. Results: The pathological details of the 190 lesions are as follows: 44 cases of submucosal invasive cancers, 61 cases of intramucosal cancers, 46 cases of tubular/villous adenomas, 12 cases of serrated adenomas, and 27 cases of hyperplastic polyps. In AFI observations, 25, 33, 100 and 32 cases were graded as 0, 1, 2 and 3, respectively. 165 cases which had been graded as 1-3, included 44 cases of submucosal invasive cancers, 61 cases of intramucosal cancers, 45 cases of tubular/villous adenomas, 11 cases of serrated adenomas, and 4 cases of hyperplastic polyps. On the other hand, the other 25 cases which had been graded as 0 contained 23 cases of hyperplastic polyps and each 1 case of tubular adenoma and serrated adenoma. Under the diagnostic criteria that neoplastic lesions were at Grade 1 or above, the sensitivity, specificity and positive predictive values were 97.6%, 92.0%, and 98.8%, respectively. In addition, differentiation of serrated adenomas from hyperplastic polyps was possible with 91.7%, 85.2%, and 73.3% sensitivity, specificity and positive predictive values, respectively, under similar diagnostic criteria. Conclusions: It was clarified that differentiations between neoplastic and non-neoplastic lesions as well as between serrated adenomas and hyperplastic polyps were possible using fluorescent property diagnoses made by grading AFI. Furthermore, it was suggested that the evaluation of AFI as an optical biopsy might be possible by establishing diagnostic criteria for endoscopic observations using AFI system, which does not require magnified observations.