Detection of Tumor Multifocality in Resectable Intrahepatic Cholangiocarcinoma: Defining the Optimal Pre-operative Imaging Modality.

Background Multiple tumor foci (MTF) in intrahepatic cholangiocarcinoma (ICC), including satellitosis and true multifocality, is a known negative prognostic factor and can inform pre-operative decision-making. Lack of standardized pre-operative liver staging practices may contribute to undiagnosed MTF and poor outcomes. We sought to investigate the sensitivity of different cross-sectional imaging modalities for MTF at our institution. Methods We identified n = 52 patients with ICC who underwent curative-intent resection from 2004 to 2017 in a multidisciplinary hepato-pancreato-biliary cancer program. Timing and modality of pre-operative imaging were recorded. Blinded review of imaging was performed and modalities were evaluated for false-negative rate (FNR) in detecting MTF, satellitosis, and true multifocality. Results Forty-one (79%) patients underwent CT and 20 (38%) underwent MRI prior to hepatectomy. MTF was pre-operatively identified in six (12%) patients. An additional seven patients had MTF discovered on final surgical pathology, despite a median interval from CT/MRI to surgery of 20 days. On blinded review the FNR of MRI compared to CT for multifocality was 0% vs. 38%, 50% vs 80% for satellitosis, and 22% vs 46% for MTF as a whole. Conclusion CT is inadequate for pre-operative diagnosis of MTF in resectable ICC, even when performed within 30 days of hepatectomy. We recommend liver-protocol MRI as the standard pre-operative imaging modality in non-metastatic ICC.