The administration of a contrast agent to obtain optimal images at three-dimensional computed tomographic (CT) angiography of the hepatic artery by using multi-detector row helical CT was investigated. Three-dimensional CT angiographic images were evaluated visually, and quantitative evaluation was performed by measuring the postcontrast CT number of the aorta. The injection rate of 5 mL/sec was significantly superior to that of 4 mL/sec in both evaluations. At administration of a contrast agent with 300 or 350 milligrams of iodine per milliliter, there were no significant differences in either evaluations. The preferable injection rate to obtain sufficient three-dimensional CT angiographic data was 5 mL/sec. (C) RSNA, 2003.