[Impact of spiral CT cholangiography on suspected obstructive jaundice]

To study spiral CT cholangiography (SCTC) before treatment in patients with obstructive jaundice due to unknown cause.

Between October 1998 and November 2000, a total of 59 patients with obstructive jaundice of unknown cause were examined by two-phase enhanced spiral CT (eSCT). Twenty-nine of these cases were excluded because they had had T-Bil of > 34 micromol/L so that their biliary duct system could not have been visualized. The remaining 30 patients were 17 male and 13 female with an age range of 31 - 76 years (mean 56.6). Pathologically, the lesion was proven to be carcinoma of pancreatic head (n = 9), Vater's ampulla carcinoma (n = 4), extrahepatic or hilar cholangiocarcinoma (n = 13), hepatocellular carcinoma (n = 1), chronic pancreatitis (n = 1) and cholelithiasis (n = 2). SCTC was performed through intravenous injection of 20 ml 50% Cholografin within 20 min before eSCT. SCTC was undertaken with parameters of a slice thickness of 2 - 3 mm, a table feed of 3 - 5 mm, a gantry time of 0.75 sec, a reconstruction interval of 1 - 2 mm, a pitch of 1.1 - 1.2, a voltage of 120 kV, a current of 220 - 240 mA, a matrix of 512 x 512 and a scan range from the level above hepatic hilum to the third segment of duodenum within 60 - 105 min following the injection. Both reconstructed SCTC source images and later eSCT scans were considered as axial CT (ACT). Multiplanar reconstruction (MPR) was obtained immediately on the operator console. 3D imaging adopted in our study was volume rendering technology (VRT) that was processed on the Siemens 3D Virtuoso workstation within 30 min. Opacification of biliary tree (OBT) analyzed by Grades 1 to 5 and image quality (IQ) assessed by 4 scales as excellent, good, fair and poor were investigated in ACT, MPR and VRT, respectively. The correlation between total OBT, which was the highest among the 3 image methods in the same case, and T-Bil, D-Bil, ALT, severity of the biliary obstruction (SBO) as well as level of the obstruction was analyzed.

In OBT, no statistically significant difference was found in the five grades by the three imaging techniques (P > 0.05), the distribution of percentages being 0, 0, 13.3%, 30.0% and 56.7% in ACT, 0, 6.7%, 20.0%, 30.0% and 43.3% in MPR and 0, 0, 13.3%, 40.0% and 46.7% in VRT. The evident correlation between total OBT and D-Bil (r(s) = -0.719), ALT (r(s) = -0.544) and SBO (r(s) = 0.650) was showed. In IQ, only a statistical significance existed between ACT and MPR (P = 0.034), having the scales "excellent to poor" in percentages of 93.3%, 6.7%, 0 and 0 for ACT, 66.7%, 30.0%, 3.3% and 0 for MPR and 70.0%, 23.3%, 6.7% and 0 for VRT, respectively.

According to our study, spiral CT cholangiography is very useful for the evaluation of selected patients with suspected obstructive jaundice before treatment.