Hepatic extracellular volume fraction obtained by dual-energy CT: a comparison of 3 and 5 minute delayed phases and correlation with clinical data

This study aimed to compare 3-minute delayed phase images with 5-minute delayed phase images for quantifying hepatic extracellular volume fraction (ECV) using dual-energy computed tomography (CT). Between January 2020 and July 2022, eighty consecutive patients with chronic liver disease (45 men and 35 women, mean age: 69.3 ± 10.4 years) were included in this study cohort. All patients underwent both 3- and 5-minute delayed phase CT scans for assessing focal liver lesions. ECV value was calculated by the iodine densities of the hepatic parenchyma and aorta, and compared between in each phase. Correlations between ECV values in each phase with the albumin-bilirubin (ALBI) score and grade, fibrosis-4 index (Fib-4), and clinical fibrosis stage were statistically analyzed. No significant difference was found in ECV values between the 3- and 5-minute delayed phase images (p = 0.056). The ratio of ECV values for 3-minute to 5-minute delayed phase images was 0.984 ± 0.078, ranging from 0.85 to 1.16. The ECV calculated on 3- and 5-minute delayed phase images showed strong and moderate correlations with ALBI grade (Spearman's ρ; 0.763 and 0.724, respectively) and ALBI score (Spearman's ρ; 0.707 and 0.668, respectively), and also showed moderate correlations with Fib-4 (Spearman's ρ; 0.548 and 0.543, respectively) and clinical fibrosis stage (Spearman's ρ; 0.468 and 0.435, respectively). Three-minute delayed phase images were found to be equivalent to 5-minute delayed phase images for the calculation of ECV.