Study On ⁶⁸Ga-PSMA-11 PET/CT Risk Stratification For Newly Diagnosed Prostate Cancer And Comparison With Pathology

PartⅠStudy on the Difference of Uptaking Volume Parameters of ⁶⁸Ga-PSMA-11 PET/CT among Risk Stratified Subgroups of Newly Diagnosed Prostate CancerObjective To explore the differences in uptaking volume parameters of Glu-CO-Lys-（Ahx）-HBED-CC PET/CT labeled with ⁶⁸Gallium(⁶⁸Ga-Prostate Specific Membrane Antigen-11 PET/CT,⁶⁸Ga-PSMA-11 PET/CT)among different risk stratified subgroups in patients with newly diagnosed prostate cancer（PCa）.Methods Image and clinical data of 85 untreated patients with PCa newly diagnosed by prostate biopsy and followed by ⁶⁸Ga-PSMA-11 PET/CT imaging in our hospital from Jan 2019 to Dec 2019 were analyzed retrospectively.According to the occurrence of tumor metastasis and the risk stratification recommended by National Comprehensive Cancer Network（NCCN）,patients were divided into binary subgroups:non-metastasis subgroup vs.metastasis subgroup and low-medium risk subgroup vs.high risk subgroup.Patients were grouped according to the three independent dimensions and boundary value of risk stratification recommended by the NCCN thereafter:taking 8 as the boundary value of Gleason score（GS）,the patients were divided into subgroups with GS<8 vs.GS≥8;taking 20 ng/m L as the boundary value of serum prostate specific antigen（PSA）,the patients were divided into subgroups with PSA≤20 ng/m L vs.PSA>20 ng/m L;taking clinical T₂/T₃staging as the boundary,the patients were divided into subgroups with clinical T₁-T₂staging vs.clinical T₃-T₄staging.Non-parametric Mann-Whitney U rank sum test of two independent samples was performed to test statistically significant differences of primary focus SUV_max(SUV_max),total volume PSMA of primary focus(PSMA-TV_primary,PSMA-TV_p),total volume PSMA of whole body(PSMA-TV_{whole body},PSMA-TV_wb),total lesion PSMA of primary focus(TL-PSMA_primary,TL-PSMA_p),total lesion PSMA of whole body(TL-PSMA_{whole body},TL-PSMA_wb)among subgroups,respectively.Results Among the 85 patients,46 patients were divided in non-metastasis subgroup（54.1%）,and 39 in metastasis subgroup（45.9%）as well as 15 patients in low-medium risk subgroup（17.6%）,and 70 in high risk subgroup（82.4%）,respectively.SUV_max（16.2 vs.9.8）,PSMA-TV_p（39.5 m L vs.10.8 m L）,PSMA-TV_wb（58.8 m L vs.10.8 m L）,TL-PSMA_p（318.4 m L vs.37.2 m L）and TL-PSMA_wb（628.0 m L vs.37.2 m L）of patients in metastasis subgroup were significantly higher than those in non-metastasis subgroup,all P<0.050;SUV_max（13.8 vs.4.2）,PSMA-TV_p（16.5 m L vs.8.4 m L）,PSMA-TV_wb（21.9 m L vs.11.4m L）,TL-PSMA_p（146.1 m L vs.27.4 m L）and TL-PSMA_wb（229.6 m L vs.28.6 m L）of patients in high risk subgroup were significantly higher than those in low-medium risk subgroup,all P<0.050;SUV_max（14.8 vs.9.9）,PSMA-TV_wb（23.9 m L vs.14.3 m L）,TL-PSMA_p（146.1 m L vs.36.3 m L）and TL-PSMA_wb（229.6 m L vs.36.3 m L）of patients in GS≥8 subgroup were significantly higher than those in GS<8 subgroup,all P<0.050,except for PSMA-TV_p（16.5 m L vs.12.5 m L,P=0.218）;SUV_max（16.2 vs.6.4）,PSMA-TV_p（24.7 m L vs.8.2 m L）,PSMA-TV_wb（41.4 m L vs.10.2 m L）,TL-PSMA_p（253.9 m L vs.28.0 m L）and TL-PSMA_wb（361.5 m L vs.29.7 m L）of patients in PSA>20 ng/m L subgroup were significantly higher than those in PSA≤20 ng/m L subgroup,all P<0.001;SUV_max（16.6 vs.9.3）,PSMA-TV_p（34.85 m L vs.10.7 m L）,PSMA-TV_wb（62.3 m L vs.14.3 m L）,TL-PSMA_p（303.5 m L vs.32.6 m L）and TL-PSMA_wb（482.1 m L vs.45.9 m L）of patients in clinical T₃-T₄staging subgroup were significantly higher than those in clinical T₁-T₂staging subgroup,all P<0.001,respectively.Conclusion The uptaking volume parameters based on ⁶⁸Ga-PSMA-11 PET/CT in patients of metastasis and of high risk with newly diagnosed PCa were significantly higher than those of non-metastasis and of low-medium risk,respectively,⁶⁸Ga-PSMA-11PET/CT can be an effective means of clinical risk stratification of prostate cancer.Part Ⅱ The Value of Serum PSA Combined with Gleason Score in Predicting the Risk of ⁶⁸Ga-PSMA-11 PET/CT Positive Metastasis of Newly Diagnosed Prostate CancerObjective To explore the value of serum PSA combined with GS of biopsy in predicting the risk of ⁶⁸Ga-PSMA-11 PET/CT positive metastasis in patients with newly diagnosed PCa.Methods Image and clinical data of 80 patients with PCa newly diagnosed by prostate biopsy and followed by ⁶⁸Ga-PSMA-11 PET/CT imaging from Jan 2019 to Sep 2019 were analyzed retrospectively.Taking metastasis or non-metastasis of PCa diagnosed by ⁶⁸Ga-PSMA-11 PET/CT as the binary dependent variable and PSA×（GS-5）as the continuous independent variable,a binary logistic regression was performed to construct a prediction model of metastasis risk,and the diagnostic efficiency was analyzed by the ROC（receiver operating characteristic）curve.The model was tested with external validation data（n=20）to explore the accuracy of regression equation in predicting metastasis.Results Among the 80 patients,44（55.0%）were included in non-metastasis group and 36（45.0%）in metastasis group.Median PSA（13.83 ng/m L vs.76.50 ng/m L,MannWhitney U=191.5,Z=-5.807,P< 0.001）and GS（7.5 vs.8,Mann-Whitney U=586.0,Z=-2.074,P=0.038）in non-metastasis group was significantly lower than that in metastasis group,respectively.The area under the ROC curve was 0.885（95% CI 0.808-0.962,P<0.001）;the best cutoff value of PSA×（GS-5）was 130.62 ng/m L,with a sensitivity of75.0%,a specificity of 95.5%,and a Yoden index of 0.705.The regression equation of logit（P）=-2.689+0.022×PSA×（GS-5）had an accuracy of 83.75%（67/80）for metastatis risk prediction.There was no significant difference between the external validation data（n=20）and the model building data（n=80）in the PSA（Z=-1.517,P=0.129）or GS（Z=-1.532,P=0.126）,the external validation data met the conditions for testing,and the accuracy of testing the regression equation was 85.0%（17/20）.Conclusion PSA combined with GS has good predictive value for the ⁶⁸Ga-PSMA-11 PET/CT positive metastasis risk of patients with newly diagnosed PCa,and the model is simple,practical,and helpful to guide clinical selection of ⁶⁸Ga-PSMA-11 PET/CT examination.Part Ⅲ Study on the Consistency between⁶⁸Ga-PSMA-11 PET/CT and Radical Prostatectomy Pathology of Newly Diagnosed Prostate CancerObjective To explore the consistency between the positive findings of ⁶⁸Ga-PSMA-11 PET/CT and pathology of radical prostatectomy in patients with newly diagnosed PCa.Methods Image and clinical data of 45 patients with PCa newly diagnosed by prostate biopsy and followed by ⁶⁸Ga-PSMA-11 PET/CT imaging from Jan 2019 to Dec2019 were analyzed retrospectively.The ⁶⁸Ga-PSMA-11 PET/CT images were qualitatively analyzed by binary classification to diagnose the involvement of prostate bilobes,capsule,seminal vesicles and regional lymph nodes.With the pathology result of radical prostatectomy after ⁶⁸Ga-PSMA-11 PET/CT imaging as the gold standard,the Mc Nemar consistency test of image-pathology paired samples was performed,and the Kappa coefficient was calculated.Pathological data and image data are mutually blind.Results The incidence of prostate bilobes,capsule,seminal vesicles and regional lymph nodes involvement diagnosed by ⁶⁸Ga-PSMA-11 PET/CT was 57.8%（26/45）,24.4%（11/45）,20.0%（9/45）,and 20.0%（9/45）,respectively;the incidence diagnosed by pathology was 93.3%（42/45）,62.2%（28/45）,35.6%（16/45）,and 13.3%（6/45）,respectively;the diagnosis accuracy of ⁶⁸Ga-PSMA-11 PET/CT was 60.0%（27/45）,57.8%（26/45）,75.6%（34/45）,and 84.4%（38/45）,respectively;the Kappa coefficients were0.075（P=0.375）,0.249（P=0.025）,0.409（P=0.003）,and 0.444（P=0.002）,respectively.Conclusion Compared with pathology of radical prostatectomy as the gold standard,⁶⁸Ga-PSMA-11 PET/CT had moderate consistency in detecting seminal vesicles and regional lymph nodes involvement in patients with newly diagnosed PCa,but low in detecting prostate bilobes and capsule involvement.