Comparison of accuracy of CT and MRI in the preoperative evaluation of malignant perihilar biliary obstruction

Abstract

Objective To summarize the imaging features of computed tomography (CT )and magnetic resonance imaging (MRI) combined with multi-technology imaging and compare its effects in the preoperative evaluation of malignant perihilar biliary obstruction. Methods The clinical data of 20 patients receiving CT and MRI who were diagnosed with malignant perihilar biliary obstruction by pathological examination at the Wuxi Second People's Hospital between January 2008 and April 2014 were retrospectively analyzed. Patients receiving CT combined with negative-contrast CT cholangiopancreatography (nCTCP) and computed tomography angiography (CTA) were allocated into the CT group, and patients receiving MRI combined with magnetic resonance cholangiopancreatography (MRCP) and magnetic resonance angiography (MRA) were allocated into the MRI group. The images of the 2 groups were analyzed by 2 independent reviewers. The classification of malignant perihilar biliary obstruction, hepatic artery and portal vein invasions and lymph node and organ metastases were evaluated respectively, and then the results of evaluation were compared with the results of surgery and pathological examinations. The comparison between the accuracy of imaging examination in the 2 groups and accuracy of perihilar biliary obstruction classification were analyzed by the chi-square test. The comparison of evaluating accuracy (sensitivity and specificity) among vascular invasion and lymph node and organ metastases were done by the receiver operating characteristic (ROC) curve analysis, and the comparison of its accuracy were done by thez-score test. Results The imagings of bile duct involvement of the 2 groups showed that there were irregular thickening bile duct wall combined with retrograde intrahepatic bile duct dilatation. The symptoms of vascular invasion included the stricture and occlusion of blood vessels or more than half of vascular contact surface with tumor. The symptoms of lymph node metastasis included the enlarging short-axis or round-like circular enhanced lesions. The symptoms of organ involvement included the unclear boundary of lesions or low-density necrotic foci within organ. All the 20 patients underwent the surgical treatment, including 13 patients with hilar cholangiocarcinoma and 7 patients with gallbladder carcinoma. Hepatic artery invasions were detected in 5 patients, portal vein invasions in 10 patients, lymph node metastases in 10 patients and organ metastases in 4 patients. The cases of classification of perihilar biliary obstruction, hepatic artery invasion, portal vein invasion, lymph node metastasis and organ metastasis which were evaluated respectively by reviewer 1 and 2 were 18/ 18, 19/ 18, 18/ 18, 17/ 16 and 18/ 19 in the CT group and 17/ 16, 14/ 13, 17/ 16, 15/ 14 and 19/ 18 in the MRI group. The imaging of the 2 groups were compared with the evaluating accuracies of classification of malignant hilar biliary obstruction, hepatic artery and portal vein invasions, lymph node and organ metastases in the 2 groups, showing no significant differences (χ2=12.593, 8.889, z=1.823, 1.956, 0.462, 0.817, 0.977, 0.751, 0.233, 1.403, P >0.05) . Conclusion CT and MRI for malignant hilar biliary obstruction had the same imaging features, meanwhile, they can provide an equivalent performance in the classification of malignant hilar biliary obstruction, hepatic artery and portal vein invasions and lymph node and organ metastases. Key words: Perihilar biliary obstruction; Malignance; Tomography, X-ray computed; Magnetic resonance imaging