The Synthesis Of 18F-PSMA-1007 And Its Comparative Study With 18F-FDG In PET/CT Imaging For Prostate Cancer

PartⅠ The synthesis of 18F-PSMA-1007 and PET/CT imaging in prostate cancerObjective:To synthesize 18F-prostate specific membrane antigen(PSMA)-1007 and perform its imaging on prostate cancer.Methods:Based on "one-step" method,18F-PSMA-1007 was produced by the CFN-MPS-200 automatic synthesis module and its quality analysis was conducted.18F-PSMA-1007 PET/CT imaging was performed in a prostate cancer patient.Results:The synthesis time of 18F-PSMA-1007 was about 50 min,and the radiochemical yield was(25.0±5.0)%(attenuation correction,n=3).The radiochemical purity was above 99.0%and was above 98.0%after 6 h.The product was colorless transparent solution with pH value of 7.0-7.5,and the specific activity was(410.0±11.0)MBq/ml and the radioactive nuclear purity was above 99.0%.PET/CT imaging in the patient showed that 18F-PSMA-1007 was highly concentrated in the prostate cancer area.Conclusion:Based on CFN-MPS-200 multifunction synthesis module,18F-PSMA-1007 can be stablely synthesized with high radiochemical yield and can be concentrated in the prostate cancer area.Part Ⅱ A comparative study of 18F-PSMA-1007 and 18F-FDG imaging in prostate cancerObjective:18F labeled PSMA-1007 presents promising results in the detection of prostate cancer,while some pitfalls exist when performing 18F-PSMA-1007 imaging.The aim of this study was to perform a comparative study of 18F-FDG and 18F-PSMA-1007 imaging.Then the pitfalls of 18F-PSMA-1007 PET/CT imaging in prostate cancer patients were analyzed.Methods:21 prostate cancer patients underwent 18F-PSMA-1007 PET/CT and 18F-FDG PET/CT before treatment.All positive lesions were noticed in both 18F-PSMA-1007 PET/CT and 18F-FDG PET/CT,and then differentiated prostate cancer metastasis from benign lesions.The SUVmax,SUVmean and TBR of lesions,up to 10 metastases and 10 benign lesions per patients,were recorded(5 for bone,5 for soft tissue metastasis).The distributions of positive lesions were analyzed for two imaging pharmaceuticals.Detection rates,SUVmax,SUVmean and TBR in 18F-PSMA-1007 PET/CT and 18F-FDG PET/CT were compared,respectively.The optimal cut-off values of SUVmax,SUVmean for metastases vs.benign lesions was found through areas under ROC in 18F-PSMA-1007.Results:1、General data of the cases:The median age for the 21 patients was 66 years(50-82 years).The Gleason score was available for 16 patients,the median Gleason score was 9(range 7-10).The median TPS A before PET/CT was 41.20 ng/mL(range 5.00-200.00 ng/mL).The median of 6.5 d(range 1.0-34.0 d)passed from 18F-PSMA-1007 PET/CT to 18F-FDG PET/CT.2、The detection rates of primary lesions in 18F-PSMA-1007 PET/CT was 100%(21/21),out of the prostate,18F-PSMA-1007 PET/CT revealed 124 positive lesions,among them,75(75/124,60%)attributed to metastases and 49(49/124,40%)attributed to a benign lesions.The detection rates of primary lesions in 18F-FDG PET/CT was 67%(14/21),extra-prostatic lesions,18F-FDG PET/CT revealed 68 positive lesions,among them,54(54/68,79%)attributed to metastases and 14(14/68,21%)attributed to a benign lesions.3、For 18F-FDG PET/CT,the SUVmax,SUVmean in metastases was significantly higher than that in benign lesions(4.42 vs.3.04 for SUVmax,2.59 vs.1.75 for SUVmean,respectively).Similarly,for 18F-PSMA-1007 PET/CT,the SUVmax,SUVmean in metastases was significantly higher than that in benign lesions(10.72 vs.3.14 for SUVmax,6.67 vs.1.91 for SUVmean,respectively),ROC suggested that SUVmax=7.71,SUVmean=5.35 might be the optimal cut-off values for metastases vs.benign lesions.4、The SUVmax,SUVmean and TBR of primary tumor in 18F-PSMA-1007 PET/CT was higher than that in 18F-FDG PET/CT(The SUVmax of primary tumor was 15.20 vs.4.20;The SUVmean of primary tumor was 8.70 vs.2.80;The TBR of primary tumor was 24.92 vs.4.82).The SUVmax,SUVmean and TBR of metastases in 18F-PSMA-1007 PET/CT was higher than that in 18F-FDG PET/CT(The SUVmax of metastases was 10.72 vs.4.42;The SUVmean of metastases was 6.67 vs.2.59;The TBR of metastases was 13.3 vs.7.91).No statistically significant difference was found when evaluating SUVmax,SUVmean of benign lesions in 18F-PSMA-1007 PET/CT and 18F-FDG PET/CT(The SUVmax of benign lesions was 3.14 vs.3.04,P>0.05,the SUVmean of benign lesions was 1.91 vs.1.75,P>0.05).Conclusion:1、the detection rate of primary tumor in 18F-PSMA-1007 PET/CT is up to 100%,and 18F-PSMA-1007 PET/CT can detect more metastases than 18F-FDG.It is important for clinical staging and treatment plan in prostate cancer.2、For 18F-PSMA-1007 PET/CT,the SUVmax,SUVmean of metastatic lesions were higher than that of benign lesions.When the SUVmax of lesions>7.71 or SUVmean of lesions>5.35,prostate cancer lesions should be highly suspected.3、The SUVmax,SUVmean and TBR of prostate cancer lesions in 18F-PSMA-1007 PET/CT were higher than those of 18F-FDG.SUVmax and SUVmean of benign lesions showed no significant difference between the two kinds of imaging.4、False positives lesions were more likely to be found in 18F-PSMA-1007 PET/CT than that in 18F-FDG PET/CT.Recognizing the source of these false positives lesions and simultaneously analyzing the characteristics of lesions and clinical data of patients’ can be helpful to improve the accuracy of diagnosis.