Detection of Colorectal Liver Metastases Using Near-Infrared Fluorescence Imaging During Hepatectomy: Prospective Single Centre UK Study

Introduction Small superficial colorectal liver metastases (CLM) may be difficult to localise intraoperatively, especially during minimally invasive hepatectomy due to reduced tactile feedback and limitations of ultrasound (US). Near-infrared (NIRF) fluorescence imaging is an emerging technology that permits detection of liver tumours after systemic injection of indocyanine green (ICG). Our aim was to report our experience using NIRF to detect CLM. Patients and Methods Patients with small, superficial resectable CLM received a 10-mg IV bolus of ICG the day before hepatectomy. All patients underwent preoperative liver-specific MRI. CLM were localised intraoperatively using a combination of white light/ultrasound (WL-US) and NIRF. Sensitivity and specificity of NIRF were compared with WL-US. Results Between March 2019 and July 2021, NIRF was utilised in 15 patients who underwent hepatectomy (laparoscopic 13, open 2). Thirty-two lesions were detected by MRI (including 3 disappearing CLM), of which 2 were ICG-negative and not resected (1 haemangioma, 1 disappearing CLM). Of 30 resected lesions, the median tumour diameter was 11 mm (range 2-25), median distance from liver surface was 4.5 mm (range 0-20) and all were confirmed CLM on histology (RO resection rate 71%). Twenty-three of thirty (77%) and twenty-seven of thirty (90%) resected CLM were detected by WL-US and NIRF, respectively. Of 7/30 (23%) resected CLM that were WL-US negative, 5 were ICG-positive. Two resected 'disappearing' CLM were ICG-positive, one of which contained viable cancer cells. Overall, NIRF influenced the operative strategy in 6 patients (43%). Conclusion Near-infrared fluorescence imaging allows detection of small, superficial colorectal liver metastases that are missed by conventional techniques and warrants further study.