[68Ga]Ga-FAPI-04 and [18F]FDG PET/CT in Patients With Primary Liver Malignancies

Abstract

Aim/Introduction:This study compares the diagnostic performanceof [68Ga]Ga-FAPI04 (FAPI) and [18F]F-FDG PET/CT in patientswith known or suspected hepatocellular carcinoma (HCC) andintrahepatic cholangiocarcinoma (ICC). Materials and Methods:Thirty-two patients undergoing FAPI, FDG PET/CT, and contrastenhanced MRI (n=28) due to suspected or known HCC (n=14) andICC (n=18) were included. All images were evaluated, documentingall lesions with abnormal uptake and classified as primary liverlesions and extrahepatic metastases. Histopathological examination(biopsy/surgery) of liver lesions was performed in 20 patients and,together with MRI, was admitted as the reference standard for thefinal diagnosis. Maximum standardized uptake values (SUVmax) ofall lesions and target-background ratio (TBR) of liver lesions weremeasured, and the sensitivity of both modalities was calculated.Results: The cohort included 32 patients (18 male, 14 female, meanage 59.2±12.8 years). The median AFP, CEA and Ca19-9 levels were545.7 ng/ml (1.7-147150), 48.5 ng/ml (1-611) and 1649 U/ml (5-13822), respectively. FDG and FAPI were positive in 21 (65.6%) and22 (%68.7) patients and in 107 and 160 lesions, of which 98 and156 were true positive, respectively. Median SUVmax and TBR werehigher on FAPI than FDG (12.1 vs. 6.0 and 5.3 vs. 2.6, respectively).The sensitivity of [68Ga]Ga-FAPI-04 and [18F]FDG/CT for detectingprimary liver tumors were 62.5% and %56.2, respectively. Theper-lesion detection rate of [68Ga]Ga-FAPI-04 PET/CT was higherthan [18F]FDG PET/CT (71.6% vs. 58.4%) for intrahepatic lesions.Regarding the extrahepatic metastases, the per-lesion detectionrate of [68Ga]Ga-FAPI-04 PET/CT was also higher than [18F]-FDGPET/CT (96.7% vs. 54.4%) Conclusion: This preliminary study showsthat the sensitivity of [68Ga]Ga-FAPI-04 PET/CT is better than [18F]-FDG PET/CT at identifying liver lesions, particularly for metastaticdisease, and its use may improve tumor staging, implementationof necessary treatment modifications and theranostic approaches.