A study of hepatic vascular anatomy and variants using multislice CT angiography

Objective: To explore the feasibility of reconstructing hepatic vessels by multislice spiral CT (MSCT) during an injection of contrast media, to optimize the delay time and postprocessing techniques of portal vein, and to discuss the accuracy of delineating hepatic arterial anatomy with MSCT compared with conventional angiography. Methods: One hundred cases were included in this study. Maximum intensity projection (MIP), surface shadow display (SSD), and volume rendering (VR) were used for all cases. 84 cases were classified into 4 groups which were performed enhanced scanning at 25 s, 50 s; 25 s, 55 s; 25 s, 60 s; and 25 s, 50 s, 75 s after the initiation of injection at the rate of 3 ml/s with the volume of contrast media according to 1.5 ml/kg body weight after plain scanning. Raw data of another 16 cases were acquired at 25 s after the initiation of contrast media injection. DSA were performed in 24 cases. Hepatic artery was classified according to Michels' anatomy. The order of portal vein and value of three post-processing techniques were compared, meanwhile, the anatomy and variants of portal vein and hepatic vein were recorded. Results: Accuracy of CTA for visualizing hepatic artery anatomy was 95.8% (23/24). Normal type of hepatic artery accounted for 69.0% (69/100), and the aberrant hepatic artery 31.0% (31/100). The image quality of portal veins in the 50 s group was better than that in the 60 s group and in the 55 s group (χ2=17.119, P<0.001). VR and MIP had a similar ability in showing the portal vein (Z =-0.805, P>0.05), and were better than SSD. Normal type of portal vein accounted for 86.9% (73/84), and the variants 13.1% (11/84). Visualization rate of hepatic vein was 60.0% (50/84) and right posterior vein 34.0% (17/50). Conclusion: It is feasible to reconstruct hepatic vessels using MSCT during an injection of contrast media. CTA has a high accuracy for delineating hepatic vascular anatomy in comparison with DSA. Using the delay time of 50 s, post-processing techniques of VR and MIP can better display the portal vein. (authors)