Indocyanine green (ICG) fluorescence in minimally invasive liver resection: The Italian Society of Endoscopic Surgery (SICE) liver ICG study

BACKGROUND: Parenchymal-sparing liver resections are increasingly used for colorectal liver metastases but may increase positive surgical margin risks. Indocyanine green fluorescence imaging may improve lesion detection and provide real-time intraoperative margin assessment. This study evaluated indocyanine green fluorescence during minimally invasive parenchymal-sparing resections for colorectal liver metastases. METHODS: The Italian Society of Endoscopic Surgery LIVER Indocyanine Green study is a multicenter, prospective cohort study including consecutive patients undergoing laparoscopic or robotic indocyanine green-guided nonanatomic wedge liver resection for colorectal liver metastases between May 2024 and December 2025. A standard 10 mg indocyanine green dose was administered the day before surgery. Intraoperative ultrasound and indocyanine green fluorescence were used for lesion localization, occult metastases detection, and real-time margin assessment. RESULTS: Overall, 57 patients underwent minimally invasive parenchymal-sparing liver resection, and 91 colorectal liver metastases were resected. Indocyanine green fluorescence identified 71 peripheral lesions and detected 2 additional subcentimeter occult metastases. Preresection fluorescence patterns included rim, partial, and total fluorescence. After resection, 4 patterns were observed: absent residual fluorescence, rim discontinuity, residual rim, and protruding rim. Complete fluorescent rim integrity was associated with R0 resection in all cases. Conversely, R1 margins (<1 mm) occurred in resections showing rim discontinuity, residual rim, or protruding rim. When R0 resection was achieved despite altered rim integrity, histopathologic margins were narrow, ranging from 1 to 3 mm. CONCLUSION: Indocyanine green fluorescence imaging successfully supported lesion detection and provided valuable real-time information on margin status during minimally invasive wedge liver resections for colorectal liver metastases. Fluorescent rim integrity represents a reliable intraoperative marker of R0 resection and should be further validated in standardized clinical trials.