Abstract

Background: Dual-Energy Computed Tomography (DECT) enables the direct measurement of iodine accumulation in the extracellular space.

Objective: To compare measures of liver fibrosis and function with Extracellular Volume (ECV) from iodine/water images using DECT.

Methods: Data was obtained from 119 consecutive patients who underwent abdominal DECT. A region of interest was set in the right lobe of the liver, pancreas, spleen, and aorta on iodine density images. ECV was calculated using the following formula: ECV = (1 − hematocrit) × [iodine concentration in the liver (or pancreas, spleen) / iodine concentration in the aorta]. The severity of liver fibrosis was estimated using the aminotransferase/platelet ratio index (APRI) and the Fibrosis-4 (FIB-4) index. Liver function was assessed by the Child-Pugh classification and albumin-bilirubin (ALBI) grade. Data were analyzed by the Spearman rank correlation coefficient, one-way analysis of variance, and post hoc analysis.

Results: The correlation between ECV and fibrosis indices (APRI and FIB-4) was only significant, with a weak magnitude for liver ECV quantification at the equilibrium phase (r=0.25 and r=0.20, respectively). The correlations between liver function index and ECV quantification were more robust than with fibrosis index. The highest correlations (r=0.50) were found between ALBI grade and liver ECV at the equilibrium phase. Liver ECV values at the equilibrium phase had a significant difference between ALBI grade 1 vs. 2 and grade 1 vs. 3.

Conclusion: Liver ECV quantification by DECT is more suitable for evaluating liver function than liver fibrosis severity.

Keywords: Dual-energy CT, extracellular volume fraction, liver fibrosis, liver functional reserve, aminotransferase/platelet ratio index (APRI), Fibrosis-4 (FIB-4) index, Child-Pugh classification, albumin bilirubin (ALBI) grade.