REAL TIME IMAGING AND QUANTITATIVE EVALUATION OF THE EMPHYSEMATOUS LUNG USING INFRARED THORACOSCOPY IN EXPERIMENTAL DOGS

Abstract

OBJECTIVES: It is necessary to determine the emphysematous region in patients undergoing lung volume reduction surgery or bullectomy. In order to remove the emphysematous region accurately, we attempted to visualize its margin using infrared thoracoscopy (IRT) with indocyanine green (ICG) intravenous injection. METHODS: Emphysema was created in the canine lung by injecting elastase via the bronchi and evaluated periodically by computed tomography and lung biopsy. IRT was performed just after injection of ICC, which becomes distributed in normal lung tissue via its abundant blood flow, and absorbs infrared at 805 nm upon irradiation by IRT. Digitalized static IRT images were prepared at specific time points and their color distribution was analyzed. After IRT, the experimental lung was examined microscopically. RESULTS: The emphysematous lung region was visualized as white and normal lung as blue in real time. The images indicated the zones of transformation between the blue-stained areas of rich blood flow and the white areas where blood flow was absent. Microscopic examination revealed that the blue-stained areas had a normal lung structure whereas the white areas were emphysematous; the zones of transformation represented marginal emphysema. CONCLUSIONS: IRT with ICG administration allowed visualization of the emphysematous lung in real time during thoracoscopic surgery in this animal model, and the images obtained revealed the margin of the emphysematous region.