Evaluation of microvessels in colorectal tumors by narrow band imaging magnification

Background: Narrow band imaging (NBI) uses optical filters for sequential green and blue illumination and narrows the bandwidth of spectral transmittance. Objective: We determined the clinical usefulness of NBI magnification for evaluation of microvascular architecture and qualitative diagnosis of colorectal tumors. Design: This study was a retrospective study. Setting: Department of Endoscopy Hiroshima University, Hiroshima, Japan. Patients and Main Outcome Measurements: A total of 189 colorectal lesions were analyzed. Each lesion was observed by NBI magnifying endoscopy and classified according to microvascular features (ie, thickness and irregularity). Microvessel thickness was classified as invisible, thin, or thick, and microvessel irregularity was classified as invisible, regular, mildly irregular, or severely irregular. NBI endoscopic images were compared with histologic findings. Results: With respect to microvessel thickness, invisible microvessels were found significantly more often in hyperplasia lesions, and thick microvessels were found significantly more often in carcinoma with submucosal massive invasion (sm-m) (P <.01). With respect to microvessel irregularity, invisible microvessels were found significantly often in hyperplasia lesions, and severely irregular microvessels were found significantly often in sm-m lesions (P <.01). Accuracy of diagnosis of sm-m on the basis of thick and severely irregular lesions was 100%. Conclusion: Microvascular features determined by NBI magnification are associated with histologic grade and depth of submucosal invasion. These results indicate that NBI magnification is useful for the prediction of histologic diagnosis and selection of therapeutic strategies of colorectal tumors.