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

Abstract 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.