MRI combined with MR cholangiopancreatography versus helical CT in the evaluation of patients with suspected periampullary tumors: a prospective comparative study

PURPOSE: To establish the diagnostic accuracy of MRI including MR cholangiopancreatography (MRCP) compared with helical CT in the differentiation of malignant and benign lesions in the periampullary region. MATERIAL AND METHODS: Fifty-one patients (27 M, 24 F, mean age 66 years, range 39-86 years) with obstructive jaundice and sonographic evidence of intra- and extrahepatic bile duct dilatation (n=31) or suspicion of periampullary tumor, based on previously performed ultrasound and/or CT examination (n=20), were studied. MRI with MRCP and helical CT were reviewed blindly under standardized conditions. Lesion status (differentiation of malignant versus benign) was rated on a 5-point diagnostic confidence scale. Reference standards for comparison were findings at surgery or laparoscopy and/ or the clinical outcome. The predictive value of imaging findings was determined with multivariate logistic regression analysis. RESULTS: The areas under the receiver operating characteristic curve were 0.96 for MRI with MRCP and 0.81 for CT (P <0.05). Multivariate analysis of eight imaging variables at MRI indicated that a stricture with malignant characteristics at MRCP was the best predictor of malignancy. CONCLUSION: MRI with MRCP was significantly more accurate than CT in differentiating between malignant and benign lesions in patients with suspected periampullary tumors, mainly due to the information obtained on the MRCP images of the biliary and pancreatic duct anatomy.