Nodular hepatocellular carcinomas: detection with arterial-, portal-, and delayed-phase images at spiral CT.

PURPOSE: To evaluate the effectiveness of three-phase spiral computed tomography (CT) for the evaluation of nodular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Images obtained at three-phase spiral CT in 45 patients with 81 nodular HCCs were reviewed. Images were obtained with 10-mm collimation and 10 mm/sec table speed during intravenous administration of 2 mL/kg 68% nonionic contrast material at a rate of 3 mL/sec. Hepatic arterial-phase (AP), portal-phase (PP), and delayed-phase (DP) images were obtained 25-30 seconds, 60-70 seconds, and 300 seconds, respectively, after injection of the contrast material. Lesion detectability and conspicuity were compared among these three protocols by two readers. RESULTS: The AP images depicted a statistically significantly larger number of lesions (n = 67), although the differences in the number of lesions depicted between the PP and DP images were not statistically significant. Twenty-one lesions were detected only with the AP images, three with the PP images, and seven with the DP images. The most clearly visualized lesions were most commonly depicted on the AP images (n = 47) rather than the PP images (n = 11) or the DP images (n = 23). CONCLUSION: Lesion detection and conspicuity were best with the AP images. However, some lesions were detected only with the DP and PP images, so that maximum lesion visualization is achieved by using all three phases.