Watershed analysis of the target pulmonary artery for real-time localization of non-palpable pulmonary nodules

Background: Some pulmonary nodules are not suitable for computed tomography-guided percutaneous localization. This study aimed to investigate the feasibility and safety of real-time localization for these non-palpable pulmonary nodules using watershed analysis of the target pulmonary artery during thoracoscopic wedge resection.

Methods: Watershed analysis is a novel technique that can be used to create a specific area on the lung surface for nodule localization. This analysis is performed by temporarily blocking the target pulmonary artery and using indocyanine green fluorescence during surgery. In our study, the surgery was simulated and evaluated preoperatively using a high-precision three-dimensional reconstruction model obtained by multidetector spiral computed tomography. The lung was observed using an infrared thoracoscopy system after an intravenous injection of indocyanine green (2.5 mg/mL), and the white-to-blue transitional zone was marked using electrocautery, after which a wedge resection was performed.

Results: A total of 25 out of 26 patients underwent successful wedge resection. The mean tumor size and depth based on computed tomography scans were 13.2±6.4 and 12.2±7.8 mm, respectively. The mean operation duration was 142.6±52.8 min. The mean bleeding volume during surgery was 12.9±9.7 mL. The mean drainage tube indwelling time was 35.6±20.0 h, and the median length of postoperative stay was 3 days (range, 2-6 days).

Conclusions: Our experience showed that the watershed analysis of the target pulmonary artery for nodule localization was safe and feasible. It may become an effective and attractive alternative method for localizing non-palpable pulmonary nodules in selected patients undergoing thoracoscopic wedge resection.