Comparison of bone scintigraphy and 68Ga PSMA PET for skeletal staging in prostate cancer
PurposeThe aim of our study was to compare the diagnostic performance of 68Ga PSMA PET and 99mTc bone scintigraphy (BS) for the detection of bone metastases in prostate cancer (PC) patients.MethodsOne hundred twenty six patients who received planar BS and PSMA PET within three months and without change of therapy were extracted from our database. Bone lesions were categorized into benign, metastatic, or equivocal by two experienced observers. A best valuable comparator (BVC) was defined based on BS, PET, additional imaging, and follow up data. The cohort was further divided into clinical subgroups (primary staging, biochemical recurrence, and metastatic castration resistant prostate cancer [mCRPC] Additionally, subgroups of patients with less than 30 days delay between the two imaging procedures and with additional single photon emission computed tomography (SPECT) were analyzed.ResultsA total of 75 of 126 patients were diagnosed with bone metastases. Sensitivities and specificities regarding overall bone involvement were 98.7 100 and 88.2 100 for PET, and 86.7 89.3 and 60.8 96.1 (p 0.001) for BS, with ranges representing results for 'optimistic' or 'pessimistic' classification of equivocal lesions. Out of 1115 examined bone regions, 410 showed metastases. Region based analysis revealed a sensitivity and specificity of 98.8 99.0 and 98.9 100 for PET, and 82.4 86.6 and 91.6 97.9 (p 0.001) for BS, respectively. PSMA PET also performed better in all subgroups, except patient based analysis in mCRPC.ConclusionGa PSMA PET outperforms planar BS for the detection of affected bone regions as well as determination of overall bone involvement in PC patients. Our results indicate that BS in patients who have received PSMA PET for staging only rarely offers additional information; however, prospective studies, including a standardized integrated x ray computed tomography (SPECT/CT) protocol, should be performed in order to confirm the presented results.
European Journal of Nuclear Medicine and Molecular Imaging