Dose optimization of nonionic contrast agent in dynamic computed tomography scanning of the abdomen and pelvis

A prospective, randomized study was performed to examine the image quality of varying reduced doses of an intravenous (IV) nonionic contrast agent (ioversol, 320 mg/ml organically bound iodine) compared with the quality obtained using the maximum permissible dose (150 ml) of the same agent. Forty-five patients referred for abdominal-pelvic computed tomography (CT) scan were randomized into five groups to receive contrast doses equivalent to 100, 75, 65, 50, or 30% of 150 ml of contrast agent. The images were scored for diagnostic image quality in eight anatomical regions of interest and, in addition, quantitative analysis of density measurements were performed in the abdominal aorta and inferior vena cava. There was no statistically significant difference in either image quality, in any anatomical region, or in vascular density measurements between the group receiving 100% and the group receiving 75% of 150 ml of nonionic contrast agent. Patients receiving 65% and lower doses demonstrated a statistically significant decrease in enhancement, although all scans were diagnostically adequate. This study demonstrates that dynamic abdominal and pelvic CT scans obtained using a reduced dose of nonionic IV contrast agent are equivalent in diagnostic im age quality compared with those scans obtained with the higher permissible dose of the same agent.