The detection of bone metastases in patients with prostate cancer or breast cancer remains a major clinical challenge. We sought to compare the diagnostic performance of 99mTc-methylene diphosphonate (99mTc-MDP) Single Photon Emission CT (SPECT) and 18Sodium F-fluoride (18F-NaF) PET–CT for the detection of bone metastases in patients with high-risk prostate or breast cancer.


MITNEC-A1 was a prospective, multicenter, single-cohort, phase 3 trial conducted at ten hospitals in Canada. Patients aged 18 years or older with breast or prostate cancer with a WHO performance status of 0 to 2 and at high risk or with clinical suspicion of bone metastases, but without previously documented bone involvement, were eligible.
18F-NaF PET–CT and 99mTc-MDP SPECT were performed within 14 days of each other for each participant. Two independent examiners interpreted each modality blind to other imaging findings. The primary endpoint was the overall accuracy of 99mTc-MDP SPECT and 18F-NaF PET–CT scans for the detection of bone metastases in the per-protocol population. A combination of histopathological, clinical, and imaging follow-up for up to 24 months was used as the gold standard to assess imaging findings. Safety was assessed in all enrolled participants. This study is registered with, NCT01930812and is complete.


Between July 11, 2014 and March 3, 2017, 290 patients were screened, of whom 288 were recruited (64 participants with breast cancer and 224 with prostate cancer). 261 participants underwent both 18F-NaF PET–CT and 99mTc-MDP SPECT and performed the tracking required for statistical analysis. The median follow-up was 735 days (IQR 727–750). According to the reference methods used, 109 (42%) of the 261 patients had bone metastases. In patient-based analysis, 18F-NaF PET–CT was more accurate than 99mTc-MDP TEMP (84 3% [95% CI 79·9–88·7] versus 77 4% [72·3–82·5]difference 6 9% [95% CI 1·3–12·5]; p=0 016). No adverse event was reported for the 288 patients recruited.


18F-NaF has the potential to displace 99mTc-MDP as the bone imaging radiopharmaceutical of choice in patients with high-risk prostate or breast cancer.


Canadian Institutes of Health Research.