Differentiating pelvic veins and enlarged lymph nodes: optimal CT techniques.

A study was done to find the best technique of administering contrast material intravenously to enable differentiation of pelvic veins and enlarged lymph nodes on computed tomographic (CT) scans. Seventy-eight patients with suspected pelvic malignancies were evaluated with CT. After precontrast scans were obtained at a selected pelvic level, 150 mL of contrast material was injected as a two-phase bolus; images were obtained at the same level 1.5, 3, 5, and 7 minutes after initiation of the bolus. Mean pelvic venous enhancement was maximal between 3 and 7 minutes in all the patients. Venous attenuation changes did not correlate with the presence of cardiac or peripheral vascular disease, but there was significantly less enhancement in patients with diabetes mellitus. The time of maximum vein enhancement begins at 3 minutes and continues for at least 4 minutes. A delayed technique of scanning the pelvis may be preferable to rapid scanning to optimize enhancement of the pelvic veins.