Iodine material density images in dual-energy CT: quantification of contrast uptake and washout in HCC

PurposeTo determine the diagnostic potential of Material Density (MD) iodine images in dual-energy CT(DECT) for visualization and quantification of arterial phase hyperenhancement and washout in hepatocellular carcinomas compared to magnetic resonance imaging (MRI).Materials and MethodsThe study complied with HIPAA guidelines and was approved by the ethics committee of the institutional review board. Thirty-one patients (23 men, 8 women; age range, 36-87years) with known or suspected Hepatocellular Carcinoma (HCC) were included. All of them underwent both single-source DECT and MRI within less than 3months. Late arterial phase and portal venous phase CT imaging was performed with dual energies of 140 and 80 kVp, and virtual monoenergetic images (at 65keV) and MD-iodine images were generated. We determined the contrast-to-noise ratio (CNR) for HCC in arterial phase and portal venous phase images. In addition, we introduced a new parameter which combines information of CNR in arterial and portal venous phase images into a single ratio (combined CNR). All parameters were assessed on monoenergetic 65keV images, MD-iodine images, and MRI. Paired t test was used to compare CNR values in Mono-65keV, MD-iodine, and MR images.ResultsCNR was significantly higher in the MD-iodine images in both the arterial (81.8740.42) and the portal venous phases (33.31 +/- 27.86), compared to the Mono-65keV (6.34 +/- 4.23 and 1.89 +/- 1.87) and MRI (30.48 +/- 25.52 and 8.27 +/- 8.36), respectively. Combined CNR assessment from arterial and portal venous phase showed higher contrast ratios for all imaging modalities (Mono-65keV, 8.73 +/- 4.03; MD-iodine, 119.87 +/- 52.94; MRI, 34.87 +/- 27.34). In addition, highest contrast ratio was achieved in MD-iodine images with combined CNR evaluation (119.87 +/- 52.94, P<0.001).Conclusion p id= Par4 MD-iodine images in DECT allow for a quantitative assessment of contrast enhancement andwashout, with improved CNR in hepatocellular carcinoma in comparison to MRI.