Detection of focal liver lesions at biphasic spiral CT: Randomized double-blind study of the effect of iodine concentration in contrast materials

PURPOSE: To evaluate the effect of iodine concentration on the detection of focal liver lesions at biphasic spiral computed tomography (CT). MATERIALS AND METHODS: One hundred two patients (64 men, 38 women) with neo plastic(n = 85) and nonneoplastic focal lesions (n = 17) were prospectively assigned to biphasic injection group A or B and received 180 mt of iopromi de containing 370 or 300 mg of iodine per milliliter, respectively, during spiral CT. Comparison included assessment of quantitative and qualitative p arameters. RESULTS: Hepatic time-attenuation curves and mean hepatic enhancement in th e portal venous phase and aortic time-attenuation curves in both arterial a nd portal venous phases were statistically superior in group A compared wit h group B. There was no significant difference in the mean enhancement in a ll lesions in either group. In contrast, among patients with hepatocellular carcinoma, mean contrast enhancement in lesions in the arterial phase was significantly superior in group A compared with group B. Blinded readers cl assified hepatic attenuation and lesion visibility as very good and as impr oved significantly more often in group A than in group B. CONCLUSION: A decrease in iodine concentration significantly affects aortic and hepatic contrast enhancement and may impair the detectability of focal liver lesions during biphasic spiral CT.