Use of contrast material for spiral CT of the abdomen: comparison of hepatic enhancement and vascular attenuation for three different contrast media at two different delay times.

Abstract

When IV contrast material was injected with a low-flow-rate monophasic bolus, a delay time of 60 sec, longer than that typically used for dynamic incremental scanning, provided greater hepatic enhancement in spiral CT. This result was significant for the three contrast media tested. Aortic attenuation was significantly greater at shorter delay times when a smaller volume of contrast material was injected. Portal vein attenuation was greater at longer delay times, suggesting that the optimal delay time may be longer than 60 sec. Further work to determine the optimal scanning window for hepatic enhancement in spiral CT by use of time-density curves is indicated.