Supplementary Material for: Subtype Classification of Intrahepatic Cholangiocarcinoma Using Liver MR imaging Features and its Prognostic Value

Introduction: Small duct (SD) and large duct (LD) subtypes of cholangiocarcinoma have been investigated for their prognostic factors. This study aimed to evaluate the diagnostic value of liver magnetic resonance imaging (MRI) in differentiating SD- and LD-types of intrahepatic cholangiocarcinoma (iCCA) and its prognostic value in predicting survival outcomes. Methods: One-hundred forty patients with surgically confirmed iCCAs (93 SD-type and 47 LD-type) who had available preoperative gadoxetic acid-enhanced liver MR images were retrospectively included. MRI features suggestive of LD-type over SD-type were analyzed using multivariate logistic analyses. Postoperative recurrence-free survival (RFS) and overall survival (OS) for 107 patients with available survival data were compared according to MRI features. Results: MRI features suggestive of LD-type included infiltrative contour (odds ratio [OR] 14.2, 95% confidence interval [CI]: 2.5 – 81.7, p = 0.003), diffuse biliary dilatation (OR 9.7, 95% CI: 1.2 – 76.9, p = 0.032), no arterial phase hyperenhancement (OR 17.8, 95% CI: 2.7 – 118.6, p = 0.003), and vascular invasion (OR 4.5, 95% CI: 1.3 – 15.4, p = 0.018). When two or more features were combined, sensitivity was 59.6% (28/47) and specificity was 95.7% (89/93) in discriminating the LD-type. RFS/OS was significantly shorter in patients with two or more MRI features, compared to those with none or one (310 days versus 529 days, p = 0.011/964 days versus 2023 days, p=0.010). Conclusions: Preoperative liver MRI may help predict the pathologic subtype of iCCAs as either the SD-type or LD-type, allowing preoperative identification of patients with poorer survival outcomes.