HEPATIC HELICAL CT - CONTRAST MATERIAL INJECTION PROTOCOL

PURPOSE: To develop and compare contrast material injection protocols suitable for hepatic helical computed tomography (CT). MATERIALS AND M ETHODS: Monophasic and biphasic helical CT were performed with contras t material with an iodine load of 50 g at 3 mL/sec for 60 seconds or a t 5 mL/sec for 10 seconds and 2 mL/sec for 65 seconds, respectively. I n 58 men and 51 women, aged 22-77 years, aortic and hepatic enhancemen t curves were constructed from a cluster acquisition with a slip-ring scanner operating in a nonhelical mode. RESULTS: The monophasic protoc ol produced a higher peak aortic enhancement (180 HU +/- 47 [+/-1 stan dard deviation]) than the biphasic protocol (150 HU + 24). Peak hepati c enhancement (63-64 HU +/- 15) was equivalent. Calculated equilibrium time for the monophasic protocol was 95.1 seconds and for the biphasi c protocol was 101.4 seconds. The contrast enhancement index differed only marginally between the two protocols (P <.4). CONCLUSION: Monopha sic and biphasic protocols produced equivalent results when tailored f or the shorter temporal window of a rapid-sequence helical acquisition .