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

Background: To explore the diagnostic performance of Multiparametric magnetic resonance imaging (mpMRI), 68 Ga-PSMA PET/CT (PET/CT) and combination of 68 Ga-PSMA PET/CT and mpMRI (mpMRI + PET/CT) for extracapsular extension (ECE). Based on the results, to predict T staging in prostate cancer. Methods: By enrolling 75 patients of prostate cancer with mpMRI and PET/CT before radical prostatectomy, we analyzed the detection performance of ECE in mpMRI, PET/CT and mpMRI + PET/CT using receiver operating characteristics (ROC) analysis. Dividing the lesions into different PI-RADS score, the improvement was analyzed by net reclassification improvement (NRI). Predictors for T staging were evaluated by using univariate and multivariable analysis. The Kappa test was used to evaluate the prediction ability. Results: From 75 patients, 50 of 103 regions were positive for ECE. AUC of mpMRI + PET/CT improved ECE diagnosis compared to mpMRI alone respectively (ΔAUC = 0.101; 95% CI, 0.0148 to 0.1860; p < 0.05, respectively). Comparing mpMRI + PET/CT to mpMRI, lesions with PI-RADS 4–5 had a significant improvement (NRI 36.1%, p < 0.01). The diagnosis of mpMRI + PET/CT was an independent predictor (p < 0.001) in logistic regression analysis. In patients with PI-RADS 4–5 lesions, 40 of 46 (87.0%) patients has correct T staging prediction (κ 0.70, p < 0.01). Conclusion: The prediction of T staging in PI-RADS 4–5 prostate cancer by mpMRI + PET/CT had a moderate performance.