Narrow Band Imaging Yields Clear Images of Subepithelial Microvessels in Large Airways in Combination With High Magnification Bronchovideoscopy

A narrow band imaging (NBI) is reported to be useful for observation of the mucosal lesions. We examined the usefulness of NBI for observation of bronchial mucosa by high magnification bronchovideoscopy. The NBI system uses 2 narrow band filters, NBI-B (390 to 445 nm) and NBI-G (530 to 550 nm). The side viewing high magnification bronchovideoscope provides information on bronchial mucosa with a maximum magnification of 110 times. Between April 2004 and July 2005, 11 patients without abnormality in large airways were enrolled into this study. Patients underwent high magnification bronchovideoscopy with the conventional imaging and the NBI. The NBI images and the conventional images were compared in regard with the following 3 parameters: vessel area ratio, vessel length ratio, and vessel area to length ratio. These parameters of the NBI-B and the NBI-G were compared. The subepithelial microvessels were more clearly visualized by NBI than by conventional imaging. Vessel area ratio and vessel length ratio were significantly higher in the NBI than in the conventional images (both P<0.0001). Thin vessels were visualized in the NBI-B, whereas the NBI-G provided images of thick vessels. Vessel area ratio and vessel length ratio were significantly higher in the NBI-B than in the NBI-G (P=0.0004, P<0.0001, respectively). Vessel area to length ratio was significantly lower in the NBI-B than in the NBI-G (P<0.0001). We concluded that NBI yielded clear images of the subepithelial microvessels. The NBI-B was good for imaging thin vessels, whereas the NBI-G was suitable for visualization of thick vessels in combination with high magnification bronchovideoscopy.