Detection of Hepatocellular Carcinoma: Comparison of Angiographic C-Arm CT and MDCT

OBJECTIVE. The aim of this study was to compare the accuracy, sensitivity, and positive predictive value of C-arm CT with those of MDCT in the detection of hepatocellular carcinoma. MATERIALS AND METHODS. We retrospectively evaluated the cases of 50 patients with nodules of hepatocellular carcinoma who underwent biphasic MDCT and selective C-arm CT with flat-detector angiographic systems. We evaluated arterial phase C-arm CT images and the corresponding biphasic MDCT images of 59 hepatic areas in 50 patients. Three independent blinded observers rated both sets of images using a detection confidence scale. The diagnostic accuracy of the two techniques was compared on the basis of area under alternative free-response receiver operating characteristic curve (A(1)). Focal accumulation of iodized oil was the reference standard. RESULTS. Accuracy was significantly higher for C-arm CT (A(1) = 0.830) than for MDCT (A(1) = 0.618) for lesions smaller than 10 mm in diameter (p < 0.001), but the accuracy of the two techniques did not differ significantly for lesions measuring 10 mm or larger. C-arm CT was significantly more sensitive than MDCT in the detection of lesions 20 mm or smaller (74.1% vs 34.0% for lesions < 10 mm [p < 0.001]; 94.7% vs 77.1% for lesions 10-20 mm [p < 0.001]). The positive predictive values of the two techniques did not differ significantly irrespective of lesion size. CONCLUSION. Compared with biphasic MDCT, C-arm CT depicted hepatocellular carcinoma lesions smaller than 10 mm with more accuracy and those 20 mm and smaller with more sensitivity. The two techniques were equally accurate in the detection of hepatocellular carcinoma lesions 10 mm in diameter and larger.