Helical CT cholangiography in the evaluation of the biliary tract:: application to the diagnosis of choledocholithiasis

Background: We evaluated the role of helical computed tomographic (HCT) cholangiography in the study of the biliary tract, especially in the detection of choledocholithiasis, and compared it with direct cholangiography. Methods: One hundred one patients with biliary lithiasic pathology undergoing direct cholangiography to rule out choledocholithiasis were included in this study. HCT was performed before and after slow infusion of cholangiographic contrast. Three-dimensional reconstructions and axial images were reviewed by two independent observers. Ultrasonography also was performed on all patients. Results: The success rate of HCT cholangiography was 99%, with only a slight reaction to the contrast. The density values were significantly higher in the distal region of the tract and showed a significant correlation with serum bilirubin levels. Anatomic evaluation of the biliary tract with CT was similar to that with direct cholangiography. Anatomic variants were found on 23 studies. Twenty-two patients had choledocholithiasis, and 21 cases were detected with HCT cholangiography. The sensitivity of this technique (95.5%) was greater than that with unenhanced CT (60%) and ultrasonography (27.3%). Maximum intensity projection reconstructions were the most valuable for detecting choledocholithiasis. Conclusion: HCT cholangiography is a reliable technique that is similar to direct cholangiography in visualizing biliary anatomy, anatomic variants, and choledocholithiasis.