DOI: 10.1007/s00259-018-4048-6Pages: 1873-1883

Comparison of [68Ga]Ga-PSMA-11 PET/CT with [18F]NaF PET/CT in the evaluation of bone metastases in metastatic prostate cancer patients prior to radionuclide therapy

1. Medical University Innsbruck, Department of Nuclear Medicine

2. Medical University Innsbruck, Department of Medical Statistics, Informatics and Health Economics

3. Medical University Innsbruck, Department of Urology

Correspondence to:
Christian Uprimny
Email: christian.uprimny@tirol-kliniken.at

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Abstract

Aim

The purpose of this study was to investigate the diagnostic performance of 68Ga-PSMA-11 PET/CT in the evaluation of bone metastases in metastatic prostate cancer (PC) patients scheduled for radionuclide therapy in comparison to [18F]sodium fluoride (18F-NaF) PET/CT.

Methods

Sixteen metastatic PC patients with known skeletal metastases, who underwent both 68Ga-PSMA-11 PET/CT and 18F-NaF PET/CT for assessment of metastatic burden prior to radionuclide therapy, were analysed retrospectively. The performance of both tracers was calculated on a lesion-based comparison. Intensity of tracer accumulation of pathologic bone lesions on 18F-NaF PET and 68Ga-PSMA-11 PET was measured with maximum standardized uptake values (SUVmax) and compared to background activity of normal bone. In addition, SUVmax values of PET-positive bone lesions were analysed with respect to morphologic characteristics on CT. Bone metastases were either confirmed by CT or follow-up PET scan.

Results

In contrast to 468 PET-positive lesions suggestive of bone metastases on 18F-NaF PET, only 351 of the lesions were also judged positive on 68Ga-PSMA-11 PET (75.0%). Intensity of tracer accumulation of pathologic skeletal lesions was significantly higher on 18F-NaF PET compared to 68Ga-PSMA-11 PET, showing a median SUVmax of 27.0 and 6.0, respectively (p < 0.001). Background activity of normal bone was lower on 68Ga-PSMA-11 PET, with a median SUVmax of 1.0 in comparison to 2.7 on 18F-NaF PET; however, tumour to background ratio was significantly higher on 18F-NaF PET (9.8 versus 5.9 on 68Ga-PSMA-11 PET; p = 0.042). Based on morphologic lesion characterisation on CT, 18F-NaF PET revealed median SUVmax values of 23.6 for osteosclerotic, 35.0 for osteolytic, and 19.0 for lesions not visible on CT, whereas on 68Ga-PSMA-11 PET median SUVmax values of 5.0 in osteosclerotic, 29.5 in osteolytic, and 7.5 in lesions not seen on CT were measured. Intensity of tracer accumulation between18F-NaF PET and 68Ga-PSMA-11 PET was significantly higher in osteosclerotic (p < 0.001) and lesions not visible on CT (p = 0.012).

Conclusion

In comparison to 68Ga-PSMA-11 PET/CT, 18F-NaF PET/CT detects a higher number of pathologic bone lesions in advanced stage PC patients scheduled for radionuclide therapy. Our data suggest that 68Ga-PSMA-11 PET should be combined with 18F-NaF PET in PC patients with skeletal metastases for restaging prior to initiation or modification of therapy.

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  • Accepted: May 2, 2018
  • Online: May 16, 2018

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