Objectives: We investigated a new technique for identifying the lung intersegmental line using infrared thoracoscopy with intravenous injection of indocyanine green.
Methods: This was an experimental animal study, and target segments were established preoperatively. Six adult beagle dogs underwent thoracotomy. After the corresponding pulmonary artery of the target segment had been ligated, indocyanine green was administered intravenously during infrared thoracoscopy. The lung was separated into 2 areas, white and blue, according to the blood flow on the monitor. We marked the visceral pleura with electrocautery along the transition zone showing a change in color from blue to white. The experimental lung was removed and subjected to pathologic and radiologic analysis.
Results: After injection of indocyanine green, infrared thoracoscopy showed that the area of normal perfusion changed to blue, whereas the area at which perfusion was absent remained white. The transition zone between colors was distinct, and the blue stain remained visible during the marking procedure. Three-dimensional computed tomographic analysis indicated that the marking separated the target segmental bronchus from the adjacent one. Detailed macroscopic and microscopic study confirmed that the marking corresponded to the intersegmental line.
Conclusion: By using infrared thoracoscopy with indocyanine green, it is possible to detect the intersegmental line without inflating the lung.