Hepatic spiral CT in children: Scan delay time-enhancement analysis

Purpose. To compare the effect of different time delays between contrast administration and the start of spiral CT scanning on hepatic enhancement in children. Materials and methods. Forty-five children (2-9 years old, mean 6 years) with no evidence of hepatic disease were examined with spiral CT. Sequential spiral scans through the entire liver were performed following a uniphasic injection of nonionic contrast medium. In group 1 scanning started at 80% of the contrast injection time, in group 2 scanning started at 100% of injection time, and in group 3 scanning started at 150% of injection time. Mean hepatic, aortic, and inferior vena caval enhancement were determined using regions-of-interest measurements. Results. Mean hepatic enhancement was 41.4, 47.0, and 40.6 HU for the 80%, 100%, and 150% injection times, respectively. Enhancement was significantly greater in the 100% injection time group (p < 0.05). A mean aortocaval difference of greater than 10 HU was present in all examinations. Conclusion. Our results suggest that delaying the initiation of spiral CT scanning until the completion of the contrast injection increases hepatic enhancement in children. These data should help to improve the quality of hepatic spiral CT in pediatric patients.