Comparison of dye-spraying chromoendoscopy and virtual chromoendoscopy for colonic dysplasia detection in longstanding Inflammatory Bowel Disease

Abstract Background Dye-spraying chromoendoscopy (DCE) is the technique of choice for colonic surveillance in patients with long-standing extensive Inflammatory Bowel Disease (IBD). Conversely, the use of virtual chromoendoscopy (VCE) is still controversial. This study aimed to compare lesion and dysplasia detection and accuracy of margins delineation between VCE and DCE. Methods Eleven gastroenterologists were given a survey with 20 pairs of pictures of IBD surveillance colonoscopies (10 with nondysplastic lesions, 5 with dysplastic lesions and 5 with no lesions). Each pair contained the same image captured during colonoscopy using VCE and DCE. The 40 pictures were randomly ordered to avoid any classification bias. For each picture, the gastroenterologist assessed the presence/absence of lesion and, when a lesion was identified, assessed the presence/absence of dysplasia and delineated its margins. To compare lesion and dysplasia detections between techniques, the sensitivity, specificity and inter-observer agreement (using fleiss’ kappa (K) test) were calculated. The chi-square test was used to assess the accuracy of margins delineation. Results When assessing lesion detection using VCE, sensitivity (S) and specificity (E) were 0.93 and 0.49 and in, DCE, 0.97 and 0.38, respectively. When assessing dysplasia detection using VCE, S and E were 0.74 and 0.60 and, in DCE, 0.67 and 0.62, respectively. Interobserver agreement analysis revealed that VCE and DCE had a moderate agreement in lesion detection - 0.57 and 0.58, respectively; however, for dysplasia detection, VCE had a fair agreement (k=0.30) and DCE a slight agreement (k=0.11). The rate of accurately defined margins was similar for both techniques (p=0.22). Conclusion Similar lesion and dysplasia detection and margins delineation were achieved with both techniques. However, concerning dysplasia detection, interobserver agreement was slightly better using VCE. Therefore, VCE may constitute a valid alternative to DCE for dysplasia screening in IBD. Further studies are needed to validate these findings.