Diagnosis of Colorectal Lesions with the Magnifying Narrow-band Imaging System

Background: Narrow-band imaging (NBI) emphasizes the surface microvasculature of the GI tract and may help in detecting small neoplasms.

Objective: The aim of this study was to clarify the value of the NBI system in tissue characterization and differential diagnosis.

Design: A prospective study.

Setting: Digestive Disease Center of Showa University Northern Yokohama Hospital.

Patients: The subjects were 495 patients who, from January 2006 to June 2007, underwent a complete colonoscopic examination. A total of 617 lesions were evaluated in the 495 patients (33 hyperplastic polyps, 532 adenomas, 52 submucosally invasive [T1] cancers).

Results: Most hyperplastic polyps showed a faint pattern. The vascular patterns of adenomas were mainly the network pattern or the dense pattern. The major vascular patterns of cancers were the irregular pattern and the sparse pattern. The irregular pattern was characteristic for protruded or flat-elevated cancers, whereas the sparse pattern was unique for depressed cancers. When we assumed that the faint pattern was diagnostic for hyperplastic polyps, we could differentiate between neoplastic and non-neoplastic lesions with a sensitivity of 90.9% and a specificity of 97.1%. Likewise, irregular and sparse patterns were assumed to be indices of massively invasive submucosal cancer, the sensitivity was 100%, the specificity was 95.8%, and the accuracy rate was 96.1%.

Limitations: This study was performed at a single center.

Conclusions: The NBI system was valuable for distinguishing between neoplastic and non-neoplastic lesions, as well as between cancers and adenomas. Vascular pattern analysis can also be a promising tool for determining treatment selection, either endoscopy or surgery.