Volumetric low-tube-voltage CT imaging for evaluating hypervascular hepatocellular carcinoma; effects on radiation exposure, image quality, and diagnostic performance

To assess the value of hepatic arterial-phase (HAP) imaging with a low tube voltage (80 kVp), using non-helical, volumetric acquisition with a 320-detector-rows area-detector CT (ADCT) scanner for evaluating hypervascular hepatocellular carcinoma (HCC) compared with routine 120-kVp HAP imaging. This study enrolled 128 patients with 148 HCCs. Seventy-six patients with 79 HCCs underwent HAP imaging with 80 kVp obtained using a 320-detector-rows ADCT scanner. The remaining 52 patients with 69 HCCs underwent routine HAP imaging with 120 kVp obtained by 64-slice helical acquisition. Image noise and tumor to liver contrast-to-noise ratio (CNR) of the two sets of images were compared. Three radiologists evaluated both sets of images using receiver operating characteristic analyses. Although there was a two-fold increase in the mean image noise with 80 kVp over that with 120 kVp (p < 0.001), no significant differences were observed in CNR among the two sets. The mean area under the curve (Az value) and the sensitivity for detecting HCC with 80 kVp (0.980, 78/79, respectively) were higher than that of 120 kVp (0.892, 55/69, respectively). HAP imaging with 80 kVp obtained by an ADCT scanner significantly improves the diagnostic performance for evaluating hypervascular HCC.