Differentiation of ampullary tumor from benign papillary stricture by thin-section multidetector CT.

The objective of this paper was to determine the criteria for differentiation of ampullary tumor from benign papillary stricture using thin-section multidetector CT images. Multidetector CT images with 2.5 mm slice-thickness in 57 consecutive patients (24 with ampulla of Vater tumor and 33 with benign papillary stricture) with extrahepatic duct dilatation due to ampullary obstruction were reviewed retrospectively. The papilla/papillary mass was evaluated regarding size, homogeneity of enhancement, attenuation value, and the diameters of extrahepatic duct and main pancreatic duct were measured. The measurability, enhancement pattern, the attenuation value of papilla/papillary mass on portal venous phase, and the maximum diameters of extrahepatic duct and main pancreatic duct were different between two groups. Multiple logistic regression analysis showed the papilla/papillary mass size was the only independently differentiating variable of ampullary tumor from benign stricture (P = 0.016) with an odds ratio of 2.424 (95% confidence interval, 1.179-4.903). The most appropriate cutoff value of papilla/papillary mass size was 12.3 mm with 91.7% sensitivity, 92.3% specificity, and 92.0% accuracy. Ampullary tumor and benign papillary stricture could be effectively differentiated by thin-section multidetector CT based on papilla/papillary mass size.