Computed tomography-guided lipiodol marking enables margin-secure wedge resection for colorectal pulmonary metastases.

Background: Achieving adequate surgical margins is crucial in pulmonary metastasectomy for colorectal cancer, but thoracoscopic resection of small, deeply situated lesions is technically demanding. Failure to obtain sufficient margins may increase the risk of local recurrence, especially when wedge resection is performed in patients who often require repeat pulmonary surgery. The aim of this study was to assess whether computed tomography (CT)-guided lipiodol marking facilitates margin-secure wedge resection. Methods: This retrospective cohort study included forty-seven patients (61 nodules <10 mm in diameter or located ≥5 mm from the pleura) who underwent lipiodol marking followed by wedge resection between 2016 and 2023. The primary outcome was a pathologic margin-to-tumor (M/T) ratio ≥1. Multivariable logistic regression with bootstrap validation was used to identify predictors of M/T ratio ≥1. Local recurrence and perioperative complications were also recorded. Results: R0 resection was obtained for all nodules and M/T ratio ≥1 was achieved in 82%. Greater tumor depth [odds ratio (OR) =0.10] and diameter (OR =0.64) were independent predictors of failure to reach M/T ratio ≥1. Local recurrence occurred only in lesions with M/T ratio <1 (36.4%). There were no serious marking-related complications. Conclusions: CT-guided lipiodol marking is safe and enables precise, lung-preserving wedge resection with adequate margins in colorectal lung metastases. These findings support its use as a valuable adjunct in thoracoscopic metastasectomy and highlight the importance of margin assessment in surgical planning.