Utility of Iodine Density-based Arterial Enhancement Fraction: Hypoenhancing Indeterminate Hepatic Nodule Differentiation

This study evaluated the utility of iodine density-based arterial enhancement fraction in differentiating hypoenhancing indeterminate hepatic nodules. A retrospective analysis was conducted on 135 patients who underwent dual-energy computed tomography between January and December 2024, including 45 with hepatocellular carcinoma, colorectal liver metastases, and cysts. To adjust for variations in contrast agent usage and imaging conditions, normalization was performed using a region of interest on the abdominal aorta. Additional regions of interest were placed on hepatic lesions and liver parenchyma for arterial enhancement fraction measurement. Pearson correlation analysis showed a strong positive correlation between Hounsfield Unit-based and iodine density-based arterial enhancement fraction (r = 0.933, p < 0.05). The mean Hounsfield Unit-based arterial enhancement fraction values were 50.83 ± 12.57% for hepatocellular carcinoma, 36.59 ± 11.23% for colorectal liver metastases, 18.57 ± 4.57% for liver parenchyma, and 0.01 ± 0.03% for cysts. The mean iodine density-based arterial enhancement fraction values were 50.02 ± 13.30%, 37.23 ± 9.63%, 22.43 ± 5.06%, and 0.04 ± 0.26%, respectively. One-way analysis of variance and post-hoc tests confirmed statistically significant differences among all groups (p < 0.05). The intraclass correlation coefficient for Hounsfield Unit-based arterial enhancement fraction indicated good reliability, while iodine density-based arterial enhancement fraction showed excellent reliability. Iodine density-based arterial enhancement fraction enables lesion quantification without non-contrast imaging, reducing radiation exposure while maintaining diagnostic accuracy. Omitting non-contrast imaging also minimizes respiratory motion artifacts, improving early detection and follow-up evaluation of hepatic malignancies.