Gadoxetic Acid-Enhanced Liver MRI for Differentiating Metabolic Predominance in Hepatocellular Carcinoma on Dual-Tracer PET/CT

Abstract

Rationale and Objectives The metabolic predominance of hepatocellular carcinoma (HCC) on dual-tracer PET/CT with C-11 acetate and F-18 fluorodeoxyglucose (FDG) reflects tumor differentiation, but a practical MRI-based biomarker for predicting this phenotype remains needed. This study aimed to assess whether enhancement patterns on gadoxetic acid-enhanced liver MRI can differentiate the metabolic predominance of HCC. Materials and Methods This exploratory retrospective study included patients with HCC who underwent both dual-tracer PET/CT and liver MRI between January 2015 and December 2021. HCC lesions were categorized as acetate- or FDG-dominant based on tracer avidity. Signal intensity (SI) in each MRI phase was quantified using the percentage signal ratio (PSR), defined as the ratio of SI in adjacent normal liver parenchyma to that in the lesion. The area under the receiver operating characteristic curve (AUC) was measured to determine the MRI phase that best distinguished the metabolic predominance of HCC lesions. Results In 38 patients (mean age, 62.0 ± 8.0 years) with 48 HCC lesions, median PSR values were lower in acetate-dominant group (28 lesions) than in FDG-dominant group (20 lesions) during the early arterial (64.7 vs. 113.9; P <0.001), late arterial (103.8 vs. 135.4; P <0.001), and portal venous (114.5 vs. 142.3; P = 0.001) phases, but not in the hepatobiliary phase (171.6 vs. 161.9; P = 0.390). The AUC was highest in the early arterial phase (0.99; 95% CI: 0.96, 1.00; P <0.001), where a PSR cutoff of 95.2 effectively distinguished the metabolic predominance of HCC. Conclusion PSR on liver MRI, especially in the early arterial phase, differentiates acetate- from FDG-dominant HCCs, indicating metabolic predominance.