Quantitative Analysis of Hypervascular Hepatic Metastases and Hepatocellular Carcinoma using Spectral CT Imaging

Abstract

Objective The goal of this study is to evaluate the performance of spectral CT-based quantitative analysis in differential diagnosis of hypervascular hepatic metastasis (HVHM) and hepatocellular carcinoma (HCC). Methods Spectral CT scans were performed for 47 patients with hepatic malignant tumors, including 20 patients with HVHM and 27 patients with HCC, which generated the following sets of data: single energy images in the arterial phase; iodine and water maps; marginal areas of lesions that manifested apparent signal intensification; and energy spectral parameters of normal liver tissues and abdominal aorta. Subsequently, we calculated the normalized iodine concentrations (NIC), lesion-normal parenchyma iodine concentration ratio (LNR), iodine concentration difference (ICD) between the arterial phase and the venous phase, and the spectral curve slope. An independent samples t test and receiver operating characteristic (ROC) curve analysis were applied to examine these quantitative parameters. Results In the arterial phase, the HVHM and HCC groups displayed no differences in NIC, LNR, or spectral curve slope (P > 0.05). In the venous phase, the two groups displayed significant differences in NIC, LNR, and spectral curve slope; the NIC was 0.59 ± 0.08 for the HVHM group and 0.4 5 ± 0.10 for the HCC group; the LNR was 1.17 ± 0.22 and 0.92 ± 0.16, respectively; the spectral curve slope was 1.85 ± 0.49 and 1.18 ± 0.34, respectively. In addition, there was no significant difference in ICD between the HVHM group (0.54 ± 0.39 g/L) and HCC group (0.45 ± 0.39 g/L) (P > 0.05). Finally, there were no significant differences of water or iodine concentration between the arterial phase and venous phase (P > 0.05). Taken together, the spectral curve slope in the portal venous phase had the best performance in differentiating HVHM from HCC. Conclusions HVHM and HCC have apparent differences in spectral curve and concentrations of radiocontrast agents in the portal venous phase. Hence, spectral CT imaging provides a new multiparameter quantitative approach for differentiating HVHM and HCC.