Material and Method: A retrospective study was performed in 55 patients with obstructive jaundice from distal common bile duct (CBD) obstruction as a result of ampullary lesion underwent 64-slice MDCT. The patients were enrolled between February 2007 and August 2014. The patients’ MDCT scans of abdomen were retrospectively evaluated by two gastrointestinal radiologists without knowledge of patient’s history, clinical data, and final diagnosis. Readers recorded the presence or absence of ampullary mass, size, shape, margin, enhancing pattern of ampullary lesion, diameter of CBD, and additional finding.

Results: CBD dilatation in malignancy and benign groups were 1.9±0.7 cm and 1.5±0.5 cm, respectively (p<0.05). Intrahepatic duct dilatation was more present in malignant ampullary lesion. Target pattern of ampullary lesion were found in only benign group (p<0.05) and pancreatic divisum were found in only malignant group (p>0.05). As compared pathological results and CT findings of benign and malignant lesions represent 95.4% sensitivity and 58.3% specificity.

Conclusion: MDCT is helpful to differentiate benign and malignant nature of ampullary lesion that causes distal CBD obstruction. Benign and malignant ampullary lesion that cause distal CBD obstruction could not be definite differentiated by size, density, and enhancement pattern on CT image but degree of CBD, intrahepatic duct dilatation, pancreatic divisum, and target pattern may be distinguished.

Keywords: Ampullary tumor, Common bile duct obstruction, Multidetector computed tomography