Liver function estimation using multiphase hepatic CT: diagnostic performance of iodine-uptake and volumetric parameters.

Abstract

Objectives: To investigate whether multiphase hepatic CT can predict liver function measured with indocyanine-green-retention test (ICG-R15) and identify patients with severe liver dysfunction contraindicating major hepatectomy, defined as ICG-R15 ≥ 20%, compared to technetium-^99m-galactosyl serum albumin (^99mTc-GSA) scintigraphy.

Materials and methods: This retrospective study included 118 patients (84 men, mean age, 69.4 ± 11.3 years) who underwent ICG-R15, ^99mTc-GSA, and multi-phase CT including early portal-venous-phase and 3-min delayed-phase. CT-derived extracellular volume fraction (ECV), iodine washout rate (IWR), liver and spleen volumes normalized by body-surface-area (LV/BSA and SpV/BSA, respectively), and ^99mTc-GSA-derived blood clearance index (HH15) and liver receptor index (LHL15) were quantified. Each parameter was compared between ICG-R15 ≥ 20% (n = 22) and ICG-R15 < 20% (n = 96) groups. Correlations with ICG-R15 were analyzed. The diagnostic performance to predict ICG-R15 ≥ 20% was assessed with areas under the receiver operating characteristic curve (AUC). Multivariable logistic regression analysis was used to identify independent CT predictors, and combined performance was determined.

Results: In the ICG-R15 ≥ 20% group, IWR (p < 0.001), LV/BSA (p = 0.026), LHL15 (p < 0.001) were lower and ECV (p = 0.001), SpV/BSA (p = 0.005), and HH15 (p < 0.001) were higher compared to ICG-R15 < 20% group. ICG-R15 showed positive correlations with ECV (r = 0.355), SpV/BSA (r = 0.248), and HH15 (r = 0.385), while negative correlations with IWR (r = -0.523), LV/BSA (r = -0.123, not statistically significant), and LHL15 (r = -0.504). The AUC of ECV, IWR, LV/BSA, SpV/BSA, HH15, and LHL15 were 0.719, 0.845, 0.653, 0.694, 0.844, and 0.878, respectively. IWR, SpV/BSA, and LV/BSA were independent predictors, with a combined AUC of 0.924.

Conclusion: IWR predicted liver function better than ECV and hepatosplenic volumetry. The combined IWR and volumetry yielded an accurate prediction of severe liver dysfunction.

Key points: Question Despite the widespread use of multiphase CT in patients with hepatobiliary diseases, its potential role in assessing liver function has been scarcely evaluated. Findings Iodine washout rate (IWR), liver volume indexed by body surface area, and spleen volume indexed by body surface area were independent predictors for severe liver dysfunction. Clinical relevance Combined IWR and hepatosplenic volumetry on routine hepatic CT may help assess hepatic function for optimizing treatment strategies and predicting patient prognosis.