Identification of the portal vein: Wedge hepatic venography with CO2 or iodinated contrast medium

Rationale and Objectives. The purpose of this study was to evaluate the uti lity of CO2 versus iodinated contrast medium for wedge hepatic venography i n identifying portal vein anatomy during transjugular intrahepatic portosys temic shunt (TIPS) procedures. Materials and Methods. Wedge hepatic venograms obtained with CO2 or iodinat ed contrast medium and direct portograms of 43 patients undergoing TIPS pro cedures were analyzed retrospectively, Wedge venography was performed in 23 patients with CO2 and in 21 with iodinated contrast medium; direct portogr aphy was subsequently performed in 42 of 44 patients with iodinated contras t medium and in one with CO2. All cases were reviewed systematically to com pare portal vein anatomy and completeness of anatomic identification betwee n direct portography and wedge venography, and the results with CO2 were co mpared to those with iodinated contrast material. Results. On the basis of opacification of the main portal trunk, branches, or both, the portal vein appearance (definition of the portal bifurcation) was good to excellent in 21 of 23 patients imaged with CO2 but in only two of 20 patients imaged with iodinated contrast medium. Wedge venograms agree d with direct portograms in 91% (21 of 23) of the CO2 cases and in 10% (two of 20) of the iodinated contrast medium cases. The two patients with poor opacification using CO2 had poor delineation of the main portal trunk, bran ches, and varices. TIPS could not be created in three patients, In two, abn ormal morphology was identified at CO2 venography; in the third, wedge veno graphy was not performed, Conclusion. Wedge hepatic venography with CO2 compared with iodinated contr ast medium has a substantially higher likelihood of correctly and completel y identifying the location and anatomy of the portal vein.