Intraoperative ultrasound staging for colorectal liver metastases in the era of liver-specific magnetic resonance imaging: is it still worthwhile?

Abstract

Background: To assess the efficacy of intraoperative ultrasound (IOUS) compared with liver-specific magnetic resonance imaging (MRI) in patients with colorectal liver metastases (CRLM). Methods: From January 2010 to December 2015, 365 patients underwent MRI as a part of preoperative work-up within one month before hepatectomy and were considered for the study. Early intrahepatic recurrence was assessed at 6 months after the resection and was considered as residual disease undetected by IOUS and/or MRI. Performance of IOUS and MRI was compared on patients by patients analysis. Long term outcomes were also studied. Results: A total of 1638 CRLM were detected by MRI. Preoperative chemotherapy was administered in 251 patients(68.8%). Intraoperatively 174 new nodules were found in 92 patients. Among 174 nodules newly identified, 151 were histologically proven CRLM (9.2% of entire series). Median size of new CRLM was 6±2.3mm. Preoperative surgical plan was intraoperatively changed in 77 patients (21%). Early intrahepatic recurrences were 15%. The sensitivity (88.2% vs 68.5%) and specificity (96.7% vs 96.4%) of IOUS were superior to MRI. Five-years overall survival (33.4% vs 51.8%, p=0.008) and 5-years disease free survival 22.4% vs 39.2%, p=0.004) were significantly worse in patients with new CRLM than without. Conclusion: IOUS improves staging in patients undergoing resection for CRLM even in the era of liver specific MRI. Intraoperative detection of new CRLM negatively affects long term outcomes.