Quantitative CT Color Mapping of the Arterial Enhancement Fraction of the Liver to Detect Hepatocellular Carcinoma

Purpose: To investigate the diagnostic value of quantitative determination and three-dimensional color mapping of the arterial enhancement fraction (AEF) of the liver for the detection of hepatocellular carcinoma (HCC). Materials and Methods: This retrospective study was approved by the institutional review board; informed consent was waived. Eighty-two patients (mean age, 56.2 years +/- 10.7 [ standard deviation]), 69 men (mean age, 57.1 years +/- 10.0) and 13 women (mean age, 51.6 years +/- 13.6), were followed-up for HCC or liver cirrhosis by using available multiphasic multidetector computed tomographic (CT) scans. Quantitative AEF color maps (the ratio of the attenuation increment during the arterial phase to the attenuation increment during the portal venous phase) of the whole liver were created from routine CT images by using prototypic software. Three radiologists independently analyzed a multiphasic CT image set; 4 weeks later, to avoid any potential recall bias, they independently analyzed a combined image set of the quantitative color maps and the multiphasic CT images. The additional diagnostic value of the color mapping was evaluated by means of jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis. Results: The mean AEF of HCCs (75.6 +/- 13.3) was significantly higher than that of liver parenchyma (23.4 +/- 8.2) (P < .001). The average JAFROC figure of merit was 0.861 on the initial multiphasic CT image set. This increased to 0.933 on the second session with the combined image set (P < .05). The mean sensitivity for HCC detection increased from 71.7% with the multiphasic CT image set to 88.8% with the combined image set. Conclusion: Quantitative color mapping of the AEF can increase the sensitivity and diagnostic performance of multiphasic multidetector CT for detecting HCC. (C) RSNA, 2009