Comparison of 68GA-FAPI-04 PET/CT and 18F-FDG PET/CT in detection of metastatic bone disease in various cancers

Objective. - Our aim in this retrospective study was to compare the diagnostic accuracy of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT in detecting bone metastases of various cancers and to evaluate the potential usefulness of 68Ga-FAPI-04 PET/CT in detecting metastatic bone disease. Material and method. - Our retrospective study included 44 patients diagnosed with bone metastases due to various cancers between January 2021 and February 2022. All patients underwent 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT imaging within 14 days. In the semi-quantitative analysis of the skeletal system, all regions with higher uptake than background activity were considered pathological. SUVmax and Metastasis-to-background ratio (TBR) values were calculated from metastatic sites. Results. - A total of 827 bone metastases were detected in our study. The diagnostic accuracies of FAPI PET/CT and 18F-FDG PET/CT were 91.8% and 81.5%, respectively (P < 0.001). When all bone metastases were compared, the SUVmax of 68Ga-FAPI-04 PET/CT was statistically significantly higher than that of 18F-FDG PET/CT (median 6.15 vs. 5.2; P < 0.001). When FDG and FAPI SUVmax values were compared according to metastasis types, FAPI SUVmax and TBR values in osteolytic, medullary and mixed type bone metastases were found to be statistically significantly higher than FDG (P-values: < 0.001, < 0.001, < 0.001, respectively). There was no statistically significant difference between FDG and FAPI SUVmax values in osteoblastic bone metastases (P = 0.26). Conclusion. - It has been shown that 68Ga-FAPI-04 PET/CT is superior to 18F-FDG PET/CT in detecting metastatic bone disease and may have more clinical impact on disease management. ?C 2023 Published by Elsevier Masson SAS.