Prospective comparison of ⁶⁸Ga-PSMA PET/CT, ¹⁸F-sodium fluoride PET/CT and diffusion weighted-MRI at for the detection of bone metastases in biochemically recurrent prostate cancer

PurposeTo prospectively compare diagnostic accuracies for detection of bone metastases by Ga-68-PSMA PET/CT, F-18-NaF PET/CT and diffusion-weighted MRI (DW600-MRI) in prostate cancer (PCa) patients with biochemical recurrence (BCR).MethodsSixty-eight PCa patients with BCR participated in this prospective study. The patients underwent Ga-68-PSMA PET/CT, a F-18-NaF PET/CT and a DW600-MRI (performed in accordance with European Society of Urogenital Radiology guidelines, with b values of 0 and 600s/mm(2)). Bone lesions were categorized using a three-point scale (benign, malignant or equivocal for metastases) and a dichotomous scale (benign or metastatic) for each imaging modality by at least two experienced observers. A best valuable comparator was defined for each patient based on study-specific imaging, at least 12months of clinical follow-up and any imaging prior to the study and during follow-up. Diagnostic performance was assessed using a sensitivity analysis where equivocal lesions were handled as non-metastatic and then as metastatic.ResultsTen of the 68 patients were diagnosed with bone metastases. On a patient level, sensitivity, specificity and the area under the curve (AUC) by receiver operating characteristic analysis were, respectively, 0.80, 0.98-1.00 and 0.89-0.90 for Ga-68-PSMA PET/CT (n=68 patients); 0.90, 0.90-0.98 and 0.90-0.94 for (NaF)-Na-18 PET/CT (n=67 patients); and 0.25-0.38, 0.87-0.92 and 0.59-0.62 for DW600-MRI (n=60 patients). The diagnostic performance of DW600-MRI was significantly lower than that of Ga-68-PSMA PET/CT and (NaF)-Na-18 PET/CT for diagnosing bone metastases (p<0.01), and no significant difference in the AUC was seen between Ga-68-PSMA PET/CT and (NaF)-Na-18 PET/CT (p=0.65).Conclusion(68)Ga-PSMA PET/CT and F-18-NaF PET/CT showed comparable and high diagnostic accuracies for detecting bone metastases in PCa patients with BCR. Both methods performed significantly better than DW600-MRI, which was inadequate for diagnosing bone metastases when conducted in accordance with European Society of Urogenital Radiology guidelines