Comparison of Two Dye Marking Methods for Preoperative Localization of Pulmonary Nodules Guided by Electromagnetic Navigation Bronchoscopy

BACKGROUND: The increasing detection of pulmonary nodules has made accurate preoperative localization clinically urgent. Although electromagnetic navigation bronchoscopy (ENB)-guided dye marking is effective, evidence is limited, and the optimal dye remains unclear. This study compared methylene blue (MB) and indocyanine green (ICG) to determine the more efficient option for pulmonary nodule localization. METHODS: A total of 101 patients who underwent preoperative ENB localization between 2015 and 2021 were included. Patients were divided into two groups according to the dye used (MB or ICG) for comparative analysis. The primary outcomes were localization success rate and ENB-related complications. Secondary outcomes included the impact of different dyes on operative efficiency, assessed by the time from the beginning of the operation to submission of the specimen for frozen section analysis (target time), concordance between intraoperative freezing and postoperative paraffin results, and 5-year overall survival (OS) and disease-free survival (DFS). RESULTS: Among 101 patients (ICG: 58 patients, 71 nodules; MB: 43 patients, 47 nodules), all nodules were successfully localized using both dyes, with no serious ENB-related complications. Compared with the MB group, ICG use was associated with a shorter target time. Consistency of intraoperative freezing and postoperative paraffin results was comparable between the two groups (p = 0.96). Five-year DFS and OS were also comparable between the two groups. CONCLUSIONS: ENB-guided dye localization enables accurate and safe minimally invasive resection of pulmonary nodules. Both MB and ICG are effective, while ICG was associated with a shorter operative time and may offer a potential efficiency benefit.