Comparison of ¹⁸F-Fluciclovine PET/CT and ^99mTc-MDP bone scan in detection of bone metastasis in prostate cancer

Objective To compare the diagnostic performance of Fluciclovine PET/CT and 99mTc-MDP bone scan in detecting bone metastases in patients with metastatic prostate cancer. Methods Patients with metastatic prostate cancer who had both Fluciclovine PET/CT and bone scan within 3-month interval between October 2017 and October 2018 in our center were retrospectively reviewed. Exclusion criteria included separate concurrent cancer, or prostate-specific antigen were more than two-fold difference with an absolute difference >1 ng/ml between the two image studies. All abnormal bone lesions on either scan were compared. The findings were verified by available pathology and 4-month clinical follow-up. Results A total of 106 patients with 106 dual scans were included in this study. 80/106 (75%) had concordant findings, whereas 26/106 (25%) had discordant findings. Of the discordant findings, 13/26 (50%) had false-positive findings on bone scan but negative on Fluciclovine PET/CT, 3/26 (11.5%) had positive lesions on Fluciclovine PET/CT but negative on bone scan, 8/26 (30.8%) had more positive lesions on Fluciclovine PET/CT than bone scan, and 2/26 (7.7%) with false-positive lesions on Fluciclovine PET/CT but negative on bone scan. The sensitivity, specificity, positive predictive value and negative predictive value for bone scan were 79%, 86%, 45% and 96%, respectively; and 100%, 98%, 89% and 100% in Fluciclovine PET/CT, respectively. Discussion Our results demonstrated that Fluciclovine PET/CT detected more bone metastases than bone scan. Importantly, there were no lesions identified by bone scan that was missed by Fluciclovine PET/CT. With the extra capacity of detecting soft tissue metastasis in PET/CT, Fluciclovine PET/CT may render bone scan unnecessary to investigate metastatic prostate cancer.