Prediction of T staging in PI-RADS 4-5 prostate cancer by combination of multiparametric MRI and ⁶⁸Ga-PSMA-11 PET/CT

Background In this study, we explored the diagnostic performances of multiparametric magnetic resonance imaging (mpMRI), (68) Ga-PSMA-11 PET/CT and combination of (68) Ga-PSMA-11 PET/CT and mpMRI (mpMRI + PET/CT) for extracapsular extension (ECE). Based on the analyses above, we tested the feasibility of using mpMRI + PET/CT results to predict T staging in prostate cancer patients.Methods By enrolling 75 patients of prostate cancer with mpMRI and (68) Ga-PSMA-11 PET/CT before radical prostatectomy, we analyzed the detection performances of ECE in mpMRI, (68) Ga-PSMA-11 PET/CT and mpMRI + PET/CT on their lesion images matched with their pathological sample images layer by layer through receiver operating characteristics (ROC) analysis. By inputting the lesion data into Prostate Imaging Reporting and Data System (PI-RADS), we divided the lesions into different PI-RADS scores. The improvement of detecting ECE was analyzed by net reclassification improvement (NRI). The predictors for T staging were evaluated by using univariate and multivariable analysis. The Kappa test was used to evaluate the prediction ability.Results One hundred three regions of lesion were identified from 75 patients. 50 of 103 regions were positive for ECE. The ECE diagnosis AUC of mpMRI + PET/CT is higher than that of mpMRI alone (Delta AUC = 0.101; 95% CI, 0.0148 to 0.1860; p < 0.05, respectively). Compared to mpMRI, mpMRI + PET/CT has a significant improvement in detecting ECE in PI-RADS 4-5 (NRI 36.1%, p < 0.01). The diagnosis power of mpMRI + PET/CT was an independent predictor for T staging (p < 0.001) in logistic regression analysis. In patients with PI-RADS 4-5 lesions, 40 of 46 (87.0%) patients have correct T staging prediction from mpMRI + PET/CT (kappa 0.70, p < 0.01).Conclusion The prediction of T staging in PI-RADS 4-5 prostate cancer patients by mpMRI + PET/CT had a quite good performance.