CIO 2022-10 Gallium-68 Fibroblast Activation Protein Inhibitor Imaging versus FDG-PET Imaging in Hepatocellular Carcinoma

Purpose: This study aims to assess the diagnostic accuracy of fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) assessment of hepatocellular carcinoma (HCC) and the benefit of using gallium-68 (68Ga) fibroblast activation protein inhibitor (FAPI) instead of FDG in the PET assessment of the same.

Materials and Methods: This study is a prospective study that has been carried out at our institution on 850 patients between January 2015 and January 2022 who were diagnosed to have HCCs on PET/CT assessment with confirmation on either biopsy or alpha-fetoprotein assessment. The maximum standardized uptake value (SUVmax) of these tumors using both FDG and 68Ga FAPI were studied and compared.

Results: A total of 850 patients had both FDG and 68Ga FAPI assessment 1 day apart. A total of 581 patients had lesions in which the largest dimension was more than 5 cm, and 269 patients had a largest lesion dimension of less than 5 cm. A total of 443 patients had background cirrhosis, and 407 patients did not have chronic liver disease. Of the total 850 patients who underwent FDG PET/CT, 781 lesions were FDG avid, and 69 lesions did not show FDG uptake, but all 850 patients who underwent 68Ga FAPI imaging showed lesion avidity. The mean SUVmax results of HCCs among the 850 patients who underwent both imaging modalities 1 day apart were 4.39 + 2.1 for FDG and 12.29 + 6.86 for 68Ga FAPI with P < 0.05 (significant). The sensitivity of FDG in detection of HCC was 92%, and that of 68Ga FAPI was 100%.

Conclusions: 68Ga FAPI PET assessment for HCC is a useful imaging tool in terms of definitive assessment of malignancy and scores higher than FDG PET in accuracy for diagnosing HCC and can possibly replace FDG in the future.