Detecting Bone Metastases in Patients With Prostate Cancer: Ga-68 PSMA Versus F-18-NaF

Research presented at the Society of Nuclear Medicine and Molecular Imaging Annual Meeting compared the diagnostic performance of Ga-68 prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) versus F-18-NaF PET/CT in detecting bone metastases in patients with prostate cancer.

Bone metastases are often present in advanced stages of prostate cancer, and imaging is important to better understand characterization, localization, number of lesions, and size. Additionally, imaging is helpful in determining how bone metastases respond during and after treatment.

Patrick Wojtylak, MSHA, CNMT, of the University Hospitals Cleveland Medical Center, and colleagues designed a study to determine whether the Ga-68 PSMA PET/CT scan or the F-18-NaF PET/CT scan is more accurate at detecting prostate bone lesions. A total of 32 patients seen in the Department of Nuclear Medicine at the University Hospitals Cleveland Medical Center received both Ga-68 PSMA PET/CT and F-18-NaF PET/CT scans within a week of each other and in no particular order. All patients were reviewed and compared by a nuclear medicine physician.

Scans were reported as positive, negative, or equivocal for bone metastases. Standard uptake values were recorded on all of the bone metastases on both the Ga-68 PSMA PET/CT and the F-18-NaF PET/CT scans.

Results of the study showed that 12 patients had equivocal bone metastases on Ga-68 PSMA PET/CT and F-18-NaF PET/CT. However, 20 patients had more bone metastases detected on the Ga-68 PSMA PET/CT scan. Of those patients, 7 had lesions that were not present on the F-18-NaF PET/CT scan.

More heterogeneity was seen on the F-18-NaF PET/CT scan than on the Ga-68 PSMA PET/CT scan, researchers added.

“Ga-68 PSMA PET/CT has a clear advantage to F-18-NaF PET/CT in terms of lesion conspicuity in patients with prostate cancer,” study authors concluded, noting that “Ga-68 PSMA PET/CT outperforms F-18-NaF PET/CT in detecting prostate bone lesions without showing the postprocedural and degenerative changes.” Thus, Ga-68 PSMA PET/CT may be considered the modality of choice for patients with suspicion for metastatic disease, even with negative conventional radiologic and F-18-NaF PET/CT imaging.