[Pre- and postoperative study of the bile ducts with spiral computerized tomography]

To investigate the capabilities of Helical CT in imaging the biliary tract after administration of an oral cholecystographic contrast agent.

Forty-five adult patients and one 8-year-old child were examined with Helical CT 12 hours after the oral administration of hyopanoic acid (3 g). All the examinations were performed with the following parameters: thickness 5 mm, pitch factor 1.5, standard reconstruction algorithm, acquisition time 20-30 s, image index 2.5 mm, 130 kV, 125 mA. In 37 cases CT was performed in patients candidate to laparoscopic cholecystectomy, in 8 cases to assess the positioning of surgical clips in patients with postcholecystectomy syndrome and in 1 case (the 8-year-old child) to confirm the US diagnosis of choledochal cystic dilatation. Helical CT images were reconstructed with a Volume Rendering (VR) software.

The extrahepatic biliary tract was visualized in all the cases with CT and VR. II grade biliary ducts were visualized in 87% (CT) and 91% (VR), III grade ducts in 76% (CT) and 78% (VR), IV grade ducts in 28% and 35%, respectively. No statistically significant difference was found between CT and VR in the visualization of the biliary structures (p > 0.05), while three-dimensional VR reconstructions improved the evaluation of the anatomical relations in the biliary tract in comparison with CT both in normal cases and in patients with congenital abnormalities of the biliary tract. Also, three-dimensional VR reconstructions were superior in assessing the correct positioning of surgical clips in patients with postcholecystectomy syndrome (p < 0.05).

Cholecysto-cholangio-CT with VR reconstructions is a reliable imaging technique for the biliary tract in patients candidate to laparoscopic cholecystectomy, to diagnose choledochal cystic dilatation and to assess the positioning of surgical clips.