Comparison of 68Ga-PSMA-617 PET/CT and 99Tcm-MDP bone scintigraphy for bone metastases in prostate cancer

Objective To compare the diagnostic differences for the detection of bone metastases between 68Ga-PSMA-617 PET/CT and 99Tcm-MDP bone scintigraphy in preliminary diagnosed prostate cancer patients. Methods Seventy-three patients who were diagnosed with prostate cancer by pathology were retrospectively analyzed from June 2017 to February 2018, and they all underwent both 68Ga-PSMA-617 PET/CT and 99Tcm-MDP bone scintigraphy without therapy beforehand. Mean age was 69.1 (range 40-88) years, the mean PSA level was 144.59 (range 5.62-1 260.00) ng/ml, and the Gleason score ranged 6-10. The patients were divided into two groups by whether or not had bone metastases according to the aforementioned two examinations. Both the sensitivity and specificity are calculated. The number of bone metastatic focus of the two examinations were also compared through the Wilcoxon rank testing. Results Thirty-two of 73 patients were diagnosed with bone metastases. 68Ga-PSMA-617 PET/CT and 99Tcm-MDP detected 32 and 31 bone metastases, with the sensitivity of 100.0%(32/32, 95%CI 89.1%-100.0%)and 90.6%(29/32, 95%CI 75.0%-98.0%), the specificity of 100.0%(41/41, 95%CI 91.4%-100.0%)and 95.12%(39/41, 95%CI 83.5%-99.4%), and the AUC of 1.000(95%CI 0.951-1.000)and 0.929(95%CI 0.844-0.976), respectively. There was significant difference in AUC between the two methods(P=0.034). Two examinations exhibited significantly different number of metastatic sites(Z=-2.949, P=0.003). Conclusions 68Ga-PSMA-617 PET/CT outperform 99Tcm-MDP bone scintigraphy for the detection of bone involvement in prostate cancer patients. It will be an important imaging supplement for prostate cancer patients and play an important role in term of the accurate treatment based on the more accurate evaluation. Key words: Prostatic neoplasms; Prostate specific membrane antigen; Bone scintigraphy; Bone metastases