68Ga-PSMA PET/CT Versus 18F-FDG PET/CT for Imaging of Hepatocellular Carcinoma

Abstract

Objectives: This study aimed to compare the metabolic parameters obtained from ¹⁸fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA) PET/CT and investigate the relationship between serum alpha-fetoprotein and PET scan parameters in patients with hepatocellular carcinoma.

Methods: Fourteen patients were recruited after dynamic magnetic resonance imaging (MRI) of the upper abdomen, and ¹⁸F-FDG and ⁶⁸Ga-PSMA PET/CT imaging studies were conducted. Regions of interest (ROIs) were drawn from lesion-free liver tissue, abdominal aorta (A), and right medial gluteal muscle (G) for the background activity. Maximum standard uptake value (SUV_max) of these regions were compared with the SUV_max of primary tumor (T).

Results: On visual assessment, five patients (36%) experienced low ¹⁸F-FDG uptake in the primary lesion, three patients (21%) experienced moderate uptake, and six patients (43%) experienced high uptake. However, only one patient (7%) showed low ⁶⁸Ga-PSMA uptake, two patients (14%) showed moderate uptake, and 11 patients (79%) showed high uptake. Four patients with a low ¹⁸F-FDG uptake showed high ⁶⁸Ga-PSMA uptake, while one patient exhibited low uptake with both ¹⁸F-FDG and ⁶⁸Ga-PSMA. The number of lesions on ⁶⁸Ga-PSMA PET/CT and MRI was significantly higher than ¹⁸F-FDG PET/CT (p=0.042 and 0.026, respectively). T/A and T/G values were significantly higher in ⁶⁸Ga-PSMA than ¹⁸F-FDG (p=0.002 and 0.002, respectively).

Conclusion: ⁶⁸Ga-PSMA PET/CT is superior to ¹⁸F-FDG PET/CT in the staging of hepatocellular carcinoma. High ⁶⁸Ga-PSMA uptake could be promising for PSMA-targeted radionuclide treatments.

Keywords: 18F-FDG; 68Ga-PSMA; AFP; Hepatocellular cancer; PET/CT.

Figure 1

A 69-year-old male diagnosed with hepatocellular carcinoma (AFP: 4.5 ng/mL) by magnetic resonance imaging. The left lobe mass showed (A) an intense ⁶⁸Ga-PSMA (T/L: 4.49), while it showed no significant ¹⁸F-FDG (B) uptake (T/L: 1.01) AFP: Alpha-fetoprotein, ⁶⁸Ga: Gallium-68, ¹⁸F-FDG: ¹⁸Fluorine-fluorodeoxyglucose, T: Tumor uptake, L: Normal liver parenchyma uptake, PSMA: Prostate-specific membrane antigen

Figure 2

A 62-year-old male with alcohol-induced cirrhosis. Magnetic resonance imaging revealed a mass compatible with hepatocellular carcinoma, showing a typical contrast enhancement pattern (not shown). AFP: 1.648 ng/mL. ⁶⁸Ga-PSMA: (A) SUV_max: 9.3; T/L 0.93. ¹⁸F-FDG: (B) SUV_max: 4.5; T/L 0.85 AFP: Alpha-fetoprotein, ¹⁸F-FDG: ¹⁸Fluorine-fluorodeoxyglucose, SUV_max: Maximum standard uptake value, PSMA: Prostate-specific membrane antigen, T: Tumor uptake, L: Normal liver parenchyma uptake

Figure 3

A 67-year-old cirrhotic male with hepatocellular carcinoma in the left lobe of the liver. ⁶⁸Ga-PSMA: (A) SUV_max: 28.1; T/L: 3.95; T/G: 31.2. ¹⁸F-FDG: (B) SUV_max: 10.1; T/L: 2.76; T/G: 7. In arterial phase CT images (C), it is seen that PSMA uptake is higher in the hyperenhancement areas and ¹⁸F-FDG uptake is higher in the non-enhancing areas of the tumor T: Tumor uptake, L: Normal liver parenchyma uptake, G: Gluteus medius muscle uptake, ⁶⁸Ga: Gallium-68, ¹⁸F-FDG: ¹⁸Fluorine-fluorodeoxyglucose, PSMA: Prostate-specific membrane antigen, SUV_max: Maximum standard uptake value, CT: Computed tomography