Integrated Dedicated Liver 18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging of Hepatocellular Carcinoma and Correlations of Positron Emission Tomography with Diffusion-Weighted Imaging and Morphological Findings.

Abstract

Purpose: This study evaluated the correlations between findings from ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET), contrast-enhanced magnetic resonance imaging (MRI), and diffusion-weighted imaging (DWI) for hepatocellular carcinoma (HCC) lesions, and differences in imaging features between the infiltrative and noninfiltrative morphological subtypes of HCC were investigated. Methods: In this retrospective study, 79 patients with HCC imaged with hepato-specific contrast-enhanced dedicated liver PET/MRI were included. Patients were grouped as positive or negative based on MRI, and the sensitivity and specificity of PET imaging were calculated. In addition, patients were classified as infiltrative and noninfiltrative, and tumor SUV, metabolic tumor volume, total lesion glycolysis (TLG), and apparent diffusion coefficient (ADC) variables were compared. Correlations between SUV, tumor size, and ADC values were investigated through regression analyses. Linear regression analyses were used to investigate the relationships between DWI-/PET-derived variables and serum alfa-feto protein (AFP) levels. Results: A total of 79 patients were included in the study. PET imaging demonstrated 77% sensitivity and 88% specificity, and 19 (27%) patients had infiltrative morphology. The infiltrative subgroup showed a higher rate of portal venous tumor thrombosis (79%), and most tumor thrombi (79%) were ¹⁸F-FDG-avid. A significant relationship was observed between tumor SUV values, ADCmin, and tumor size. Serum AFP levels correlated with SUV_peak (R² = 0.223) and TLG (R² = 0.283; both p < 0.001) values. Conclusions: Higher ¹⁸F-FDG uptake was observed in infiltrative lesions compared with noninfiltrative ones. The majority of malignant tumor thrombi exhibited increased ¹⁸F-FDG uptake. Although the ability of ¹⁸F-FDG PET to detect HCC lesions is limited by the variable uptake in HCC tumors, it proves valuable in assessing tumor aggressiveness.