Detection of hypervascular modular hepatocellular carcinomas: Value of triphasic helical CT compared with iodized-oil CT

OBJECTIVE. The objective of this study was to compare the capability of arterial, portal venous, and delayed phases of helical CT with that of iodized-oil CT for revealing nodular hepatocellular carcinomas. MATERIALS AND METHODS. Forty-eight patients with nodular hepatocellular carcinomas underwent triphasic helical CT examination with l0-mm collimation at 10-mm/sec table speed. We injected 120 mi of contrast material (36 g of iodine) at the rate of 3 ml/sec. Arterial-phase, portal venous-phase, and delayed-phase images were obtained with 30-sec, 65-sec, and 360-sec delays, respectively. All 48 patients also underwent angiography and intraarterial infusion of iodized oil after helical CT; iodized-oil CT was performed about 2 weeks after infusion of iodized oil. Helical CT images were compared with iodized-oil CT images for revealing hepatic nodules. RESULTS. In 48 patients, 79 hepatocellular carcinomas were seen with iodized-oil CT. Using helical CT, the arterial phase revealed 68 lesions (86%), the portal venous phase revealed 53 lesions (67%), and the delayed phase revealed 57 lesions (72%). The arterial phase proved superior to the portal venous and delayed phases for revealing lesions (p = .0025). The portal venous phase showed no significant difference for revealing lesions compared with the delayed phase. When combined, helical CIT of the arterial anl-l portal venous phases revealed 73 lesions (92%); a combination of the arterial and delayed phases revealed 72 lesions (91%); and a combination of the portal venous and delayed phases revealed 63 lesions (80%). Any combination of two phases that included the arterial phase proved superior to the combination of the portal venous and delayed phases (p = .0033). Overall, the combination of the arterial and portal venous phases (92%) or the combination of all three phases (92%) proved best at revealing lesions. CONCLUSION. The arterial phase of helical CT is better for revealing nodular hypervascular hepatocellular carcinoma than are the portal venous and delayed phases. The combination of the arterial and portal venous phases is superior to the arterial phase alone. Also, the combination of the arterial and portal venous phases is equal to the combination of the three phases for revealing hypervascular hepatocellular carcinomas.