Multidetector computed tomography assessment of vascular involvement in perihilar cholangiocarcinoma

Background In approximately 40% of patients with perihilar cholangiocarcinoma (PHC), the tumor is deemed unresectable at laparotomy, often due to vascular involvement. On imaging, occlusion, narrowing, wall irregularity and >180° tumor-vessel contact have been suggested to predict vascular involvement in patients with PHC. The objective of this study was to correlate computed tomography (CT) findings in PHC with surgical and histopathological results, in order to evaluate the accuracy of currently used CT criteria for vascular involvement. Methods Patients with PHC undergoing exploration in a single tertiary center (2015-2018) were included. Tumor-vessel relation of portal vein and hepatic artery on CT were scored by two independent radiologists, blinded for surgical and pathological outcomes. Intraoperative findings were scored by the surgeon in theatre or derived from operation/pathology reports. Results A total of 42 CT scans were evaluated, resulting in assessment of 115 vessels. Portal vein occlusion, narrowing and presence of an irregular wall on CT corresponded with a positive predictive value (PPV) for involvement of 100%, 83% and 75%, respectively. For the hepatic artery, PPV of occlusion and stenosis was 100%, whilst other criteria had PPV 180° contact, narrowing, irregularity or occlusion) resulted in PPV, sensitivity and specificity of 85%, 67% and 94%, respectively, for the portal vein and 53%, 40% and 75%, respectively, for the hepatic artery. Conclusions Prediction of vascular involvement on CT is more difficult for the hepatic artery than for the portal vein. Suggestion of hepatic artery invasion on imaging, other than occlusion or stenosis, should not preclude surgical exploration.