Dual Energy CT-Derived Liver Extracellular Volume Fraction for Assessing Liver Functional Reserve in Patients with Liver Cirrhosis

<i>Background and Objectives</i>: The extracellular volume fraction (fECV) of the liver, as measured by contrast-enhanced computed tomography (CT), has been shown to correlate closely with the histological stages of hepatic fibrosis. This study aimed to investigate the diagnostic performance of a liver extracellular volume fraction derived from dual-energy CT (DECT) for evaluating liver functional reserve based on the Child-Pugh class in cirrhotic patients, compared with other noninvasive markers. <i>Materials and Methods</i>: This retrospective study included 258 patients with liver cirrhosis who underwent contrast-enhanced DECT. The fECV was measured using iodine maps derived from equilibrium phase images obtained 3 min after contrast injection at 100/140 Sn kVp. Statistical analyses included Welch's ANOVA with post hoc tests, Spearman's correlation, and ROC analysis. The area under the curve (AUC) was compared among fECV and other noninvasive markers (aspartate transaminase to platelet ratio index [APRI], Fibrosis-4 [FIB-4], and model for end-stage liver disease [MELD]) using DeLong's test. Intra- and interobserver reliability of fECV was assessed with the intraclass correlation coefficient (ICC). The area under the receiver operating characteristic curve (AUC) for differentiating Child-Pugh classes was compared among the fECV and other noninvasive markers (aspartate transaminase to platelet ratio index [APRI], Fibrosis-4 [FIB-4], and model for end-stage liver disease [MELD]). <i>Results</i>: The fECV increased significantly with advancing Child-Pugh classes (<i>p</i> < 0.001), showing a moderate correlation with Child-Pugh class (r = 0.53). The mean differences in fECV among the Child-Pugh classes were 8.88 between A and B (95% confidence interval [CI], 5.85-11.92; <i>p</i> < 0.001) and 7.42 between B and C (95% CI, 1.92-12.91: <i>p</i> < 0.001). The AUC for differentiating Child-Pugh classes A and B demonstrated no significant differences among the fECV (0.84), APRI (0.83, <i>p</i> > 0.99) and FIB-4 (0.83, <i>p</i> > 0.99), except for MELD, which had a significantly higher AUC (0.94, <i>p</i> = 0.047). For differentiating Child-Pugh classes B and C, the fECV demonstrated a significantly higher AUC (0.78), compared with FIB-4 (0.50, <i>p</i> = 0.038) and APRI (0.49, <i>p</i> = 0.037), whereas no significant difference was observed between fECV and MELD (0.92, <i>p</i> = 0.12). The intra- and interobserver reliabilities of the fECV measurements were excellent (ICC, 0.93; 95% CI, 0.91-0.95 and 0.91; 95% CI, 0.88-0.92, respectively). <i>Conclusions</i>: DECT derived fECV is a useful noninvasive marker for assessing liver functional reserve based on the Child-Pugh classification.