18F-FLUORIDE PET/CT vs 18F-PSMA-1007 TO DETECT BONE METASTASES IN PROSTATE CANCER – A HEAD-TO-HEAD PROSPECTIVE COMPARISON

Introduction/Justification

There have been no head-to-head prospective studies comparing the ability of 18F-Fluoride PET/CT and 18F-PSMA-1007 PET/CT to detect bone metastases due to prostate cancer. So, this study aims to investigate the capacity of 18F-PSMA-1007 to detect bone metastases compared to the reference standard (18F-Fluoride PET/CT) in PCa patients, considering mainly the presence or absence, number and biodistribution of lesions.

Objectives

This prospective study aimed to compare the ability of 18F-PSMA-1007 PET/CT and 18F-Fluoride PET/CT to detect bone metastases.

Materials and Methods

Twenty-eight patients with prostate cancer biochemical recurrence were submitted to both 18F-PSMA-1007 PET/CT and 18F-fluoride PET/CT studies. These two radiotracers evaluated the presence or absence, number of lesions, body and bone localization, lesion pattern, and probability of malignancy.

Results

Twenty-eight patients with prostate cancer biochemical recurrence, mean age of 70.8 ± 8.7 years; Gleason score = 7.72 ± 1.23 and the mean total PSA = 50.2 ± 183.9 ng/mL were included. On a per-patient basis, considering that 18F-Fluoride PET/CT is the gold standard, the 18F-PSMA-1007 PET/CT presented a concordance rate of 96.43%, sensitivity (S) of 92.3%, specificity (E) of 100%, predictive positive value (PPV) of 100% and predictive negative value (PNV) of 93.80% on lesion detection. Evaluating the number of lesions, 18F-PSMA-1007 PET/CT determined a PPV of 91.8% and sensitivity of 86.5%. Bone localization in 18F- Fluoride and 18F-PSMA-1007 were predominant in the dorsal spine (34.62%/62.65%), ribs (32.69%/32.65%)and pelvis (9.62%/12.24%), respectively. Both studies had a concordant rate of 80.76% on rib evaluation, the most conflicting site of uptake between the methods in actual literature.

Conclusion

18F-PSMA-1007 has the same ability as 18F-Fluoride to detect PCa bone metastasis in biochemical recurrence, with concordance of 96,43% and 80,00% on a per-patient and per-lesion evaluation, respectively. Both studies demonstrated predominancy of sclerotic and medullar lesions, located preferentially on dorsal spine and ribs, being the last one concordant in 80,76% of studies.