Pediatric hepatic CT: An injection protocol

Abstract

Objective. To determine an injection protocol for pediatric hepatic CT and to investigate the use of power injection.Materials and methods. Eighty-seven studies were prospectively performed using ioversol (320 mg iodine per cc) at 2 cc/kg. Three techniques were used: helical (1 s/slice); dynamic, non-breath-hold (5.5 s/slice); dynamic, breath-hold (10 s/slice) scans. The liver-scan time for each study was determined. Scan initiation ranged from 25 to 80 s. An injection duration (50–100 seconds) was selected. From the contrast volume (2 cc/kg × kg body wt) and injection duration, the injection rate (cc/s) was calculated for each patient. Each study was grouped by injection rate corrected for body weight (cc/kg/min) into: 1.2–1.5, 1.51–2.0, and 2.01–2.4. The aortic/liver attenuation curves were plotted for each group.Results. Liver-scan time for helical studies was a mean of 26 s, for dynamic, non-breath-hold studies 75 s, dynamic breath-hold scans were 154 s. Injection rates of 1.2–1.5 cc/kg/min produced a scanning interval of 165 s. Injection rates of 1.51–2.0 cc/kg/min produced a scanning interval of 120 s. Injection rates of 2.01–2.4 cc/kg/min produced a scanning interval of 90 s. There was no increase in hepatic attenuation for the injection rates 2.01–2.4 cc/kg/min compared with 1.51–2.0 cc/kg/min. There was one complication related to injection through a central line.Conclusions. An injection protocol was determined for helical studies with injection rates of 1.7–2.0 cc/kg/min with initiation at 60 s; for dynamic, non-breath-hold studies with injection rates of 1.5–1.7 cc/kg/min with initiation at 50 s; and for dynamic breath-hold studies with injection rates of 1.2–1.5 cc/kg/min with initiation at 45 s. Power injection was used safely in our population.