Prediction of colorectal tumor grade and invasion depth through narrow-band imaging scoring

Figure 1 Study design. Schematic of the retrospective study of resected specimens used develop and validate a novel statistical model based on narrow-band imaging findings for the diagnosis of colorectal lesions. All patients were of Japanese ethnicity and comprised 85 men and 53 women with a mean age of 65.7 ± 10.1 years. NBI: Narrow-band imaging; SM: Submucosa.

Figure 2 Classification of surface patterns of colorectal tumors as revealed by narrow-band imaging. Colorectal lesions were broadly classified into tubular or papillary types, based on narrow-band imaging observations of histopathologic appearances and proliferation patterns; this was followed by an evaluation of the microstructure of the superficial layer of each lesion. Regarding the surface pattern, lesions with a clearly visualized surface microstructure were defined as the “clear type,” whereas lesions with a visualized but not readily discerned surface microstructure were defined as the “unclear type.” Lesions with a surface microstructure characterized by uniformly-sized pits in a regularly arranged pattern were defined as the “regular type,” whereas those with an irregular pit size and arrangement were defined as the “irregular type.” Representative images are shown. Magnification: 125 ×.

Figure 3 Vascular patterns of colorectal tumors as revealed by narrow-band imaging endoscopy. Colorectal lesions were broadly classified into tubular or papillary types based on narrow-band imaging observations of the histopathologic appearances and proliferation patterns, followed by an evaluation of the microvessel architecture. “Disturbed arrangement” was defined as a disturbance in the form, size, and arrangement of microvessels; “disrupted vessels” was defined as an evident disruption of the microvessels; “varied caliber” was defined as a variance of caliber in the same vessel; “size irregularity” was defined as variance in caliber among different vessels; “thick vessels” was defined as an area harboring cyan-colored vessels relative to vessels in adjacent areas; “avascular area” was defined as an area with no visible vessels; and “vessel meandering” was defined as evident meandering of the blood vessels along a twisting and winding path. Representative images are shown. The locations of vessels representative of each vascular pattern and classification are denoted by arrowheads. Magnification: 125 ×.

Figure 4 Development of a model for predicting the tumor grade and depth of submucosal invasion in colorectal tumors based on narrow-band imaging findings. The associations of surface and vascular patterns [as visualized by narrow-band imaging (NBI)] with the tumor grade (A) and depth of submucosa (SM) invasion (B) were analyzed in a multivariate analysis based on a logistic regression model, followed by the stepwise selection of variables from the NBI findings. A scoring system was established based on the statistical values thus estimated, and a model was developed for predicting the tumor grades and SM invasion depths of colorectal tumors. ROC: Receiver operating characteristic; AUC: Area under the curve.