High resolution chromo-endoscopy: An affordable and accurate non-biopsy technique for predicting histology of colorectal polyps

Background: Visual, non-biopsy techniques for predicting histology of diminutive colorectal polyps have not proven reliable. We recently reported our initial experience using a high resolution colonoscope (HRC). the Fujinon EC-400 HM/HL. in combination w/indigo carmine dye (ICD) for the diagnosis of small polyps. The sensitivity and specificity of our technique in distinguishing adenomatous from non-adenomatous polyps was 93% and 95%. respectively. Clinical application of this technique was limited by the cost of the HRC and accompanying video processor ($55K). We now report on our more recent experience utilizing a less expensive 2nd generation HRC (cost of scope/video processor = $25K). Methods: Complete colonoscopy using the Fujinon EC-200LR was performed in patients w/polyps. All polyps <10mm were sprayed w/ 0.4% ICD and subsequently photographed. Histologic diagnosis was predicted based on the polyps surface architecture ("pit pattern"=hyperplastic (HP). "grooves/sulci"=adenomatous (AP)). All polyps were then subjected to either biopsy or polypectomy All histologic diagnosis were reviewed and confirmed by a single blinded pathologist. Results: 58 polyps w/a mean diameter of 4.5mm were evaluated from 34 patients. Actual Histology Predicted Histo: AP Predicted Histo: HP Diagnostic Accuracy AP (n=26) 25 1 96% HP (n=25) 3 22 88% Other (n=7)*3 4 NA*lymphoid aggregate (n=6). fragment w/cautery effect (n= 1) When attempting to separate AP from non-AP (HP+Other) this technique has a sensitivity of 96% and a negative predictive value of 96% (ie., if a polyp is predicted to be hyperplastic there is a 96% (26/27) likelihood that it is not a AP). Retrospective video review of the one mispredicted AP revealed a predominant "pit" or "dot" pattern but also a single central grove. Conclusions: HRC in combination w/ ICD is very effective in separating non-AP form AP. The more affordable 2nd generation Fuinon HRC is equally capable of providing visual data that may allow endoscopists to predict histology w/o biopsy thus reducing the cost of colon cancer screening.