Detection of biliary duct narrowing and choledocholithiasis: Accuracy of portal venous phase multidetector CT

Purpose: To retrospectively evaluate the sensitivity and specificity of 64-detector computed tomography (CT) in the portal venous phase by using transverse images and both multiplanar and minimum intensity reformations for the detection of biliary duct narrowing and choledocholithiasis, with magnetic resonance cholangiopancreatography (MRCP) or endoscopic retrograde cholangiopancreatography (ERCP) as the reference standard. Materials and Methods: Approval from institutional review board was obtained for this HIPAA-compliant retrospective study; informed consent was waived. The study included all patients (42 men, 52 women; mean age, 61 years) who underwent abdominal 64-detector CT within 2 months of MRCP and/or ERCP. All patients underwent portal venous phase intravenous contrast material-enhanced abdominal CT. Sixty-one patients underwent MRCP and 54 patients underwent ERCP (21 patients underwent both). Two radiologists, blinded to the reference standard, independently evaluated the CT images, including multiplanar and minimum intensity reformations, for biliary duct narrowing and choledocholithiasis. Standard of reference examinations were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Twenty-three (24%) of 94 patients had a biliary duct narrowing at reference examinations. For detecting biliary duct narrowing, observer 1 had a sensitivity of 78.2%, specificity of 100%, PPV of 100%, and NPV of 93.4% and observer 2 had a sensitivity of 69.6%, specificity of 100%, PPV of 100%, and NPV of 91.0%. In 18 (19%) of 94 patients, choledocholithiasis was detected at reference examinations. For detecting choledocholithiasis, observer 1 had a sensitivity of 77.8%, specificity of 96.1%, PPV of 82.4%, and NPV of 94.8% and observer 2 had a sensitivity of 72.2%, specificity of 96.1%, PPV of 81.2%, and NPV of 93.6%. Conclusion: Portal venous phase multidetector CT images are highly specific and moderately sensitive for the detection of biliary duct narrowing and choledocholithiasis.