Objectives: To determine the diagnostic accuracy of 68gallium prostate-specific membrane antigen (PSMA)-based positron emission tomography/computed tomography (PET/CT) in comparison with 18F-fluoride-based PET/CT (NaF-PET/CT) and whole-body magnetic resonance imaging (WB-MRI) for the detection of bone metastases in patients with prostate cancer.
Methods: Sixty patients with prostate cancer were included in the period May 2016 to June 2017. The participants underwent three scans (index tests) within 30 days: a NaF-PET/CT, a WB-MRI and a PSMA-PET/CT. Experienced specialists assessed the scans. In the absence of a histological reference standard, the final diagnosis was determined as a panel diagnosis. Measures of the diagnostic performances of the index tests were calculated from patient-based dichotomous outcomes (0 or ≥ 1 bone metastasis) and pairwise compared (McNemar test). For each index test, the agreement with the final diagnosis with regard to the number of bone metastases detected (0, 1-5, > 5) and the inter-reader agreement was calculated (kappa coefficients).
Results: Fifty-five patients constituted the final study population; 20 patients (36%) were classified as having bone metastatic disease as their final diagnosis. The patient-based diagnostic performances were (sensitivity, specificity, overall accuracy) PSMA-PET/CT (100%, 100%, 100%), NaF-PET/CT (95%, 97%, 96%) and WB-MRI (80%, 83%, 82%). The overall accuracy of PSMA-PET/CT was significantly more favourable compared to WB-MRI (p = 0.004), but not to NaF-PET/CT (p = 0.48). PSMA-PET/CT classified the number of bone metastases reliably compared to the final diagnosis (kappa coefficient 0.97) and with an "almost perfect" inter-reader agreement (kappa coefficient 0.93).
Conclusions: The overall accuracy of PSMA-PET/CT was significantly more advantageous compared to WB-MRI, but not to NaF-PET/CT.
Key points: • PSMA-PET/CT assessed the presence of bone metastases correctly in all 55 patients • PSMA-PET/CT was more advantageous compared to WB-MRI • No difference was found between PSMA-PET/CT and NaF-PET/CT.
Keywords: Bone and bones; Magnetic resonance imaging; Metastasis; Positron emission tomography computed tomography; Prostatic neoplasms.