Value of MRI in the diagnosis of main bile duct stones The sensitivity, specificity, accuracy, positive predictive value, negative predictive value of MRI in the diagnosis of stone position were, respectively: 97.05%; 93.75%; 96.42%; 98.51%; 88.23% for main extra-hepatic bile duct, 95.65%; 94.73%; 95.23%; 95.65%; 94.73% for right intrahepatic bile ducts, 96.49%; 88.98%; 94.04%; 94.82%, 92.30% for left intrahepatic bile ducts.