One-stop shop whole-body ⁶⁸Ga-PSMA-11 PET/MRI compared to clinical Nomograms for preoperative T and N-Staging of High-Risk Prostate Cancer

Objectives: To assess the diagnostic potential of one-stop shop PSMA-ligand Positron Emission Tomography/Magnetic Resonance Imaging (⁶⁸Ga-PSMA-11 PET/MRI) compared to preoperative clinical preoperative staging nomograms in patients with high risk prostate cancer (PC).

Methods: A total of 102 patients underwent ⁶⁸Ga-PSMA-11 PET/MRI prior to intended radical prostatectomy (RP) with pelvic lymph node dissection (PLND). For ⁶⁸Ga-PSMA-11 PET/MRI one experienced reader determined T and N-stage. Preoperative variables were used to calculate probabilities for the MSKCC nomogram and Partin tables and subsequent receiver operating characteristic (ROC) curves to determine discriminatory cutoffs. On cohort base positivity rates of ⁶⁸Ga-PSMA-11 PET/MRI and nomograms were compared to pathological prevalence. On patient base sensitivity, specificity and its area under the curves (AUCs) were calculated and pairwise tested for statistical difference. Finally, on patient base the full concordance of each method to postoperative T- and N-stage was determined.

Results: 73 patients could be included in the final analysis. On cohort base for LNM positivity rate was most concordant with pathological prevalence (34.3%) for the MSKCC nomogram (39.7%) compared to Partin tables (14.1%) and imaging (20.6). Prevalence of ECE (72.6%) was best predicted by MSKCC nomograms and imaging (83.6% each), SVI (45.2%) by imaging (47.9%). On patient base AUCs for LNM, ECE and SVI did not differ significantly between the tests (p>0.05). Imaging revealed to high specificity (100%) for LNM and sensitivity (60%) comparable to the MSKCC nomogram (68%) and Partin tables (60%). For ECE, imaging revealed the highest sensitivity (94.3%) compared to the MSKCC nomogram (66%) and Partin tables (71.1%). For SVI, sensitivity and specificity of imaging and MSKCC nomograms were comparable (81.5% and 80% vs. 87.9% and 75%).The rate of full concordance to the final pTN-stage for a prediction device was was 60.3 % for imaging, 52.1% for the MSKCC nomogram and 39.7% for Partin tables.

Conclusions: In our analysis in high-risk PC patients preoperative one-stop shop ⁶⁸Ga-PSMA-11 PET/MRI performs at least equally well in analysis of separate T- and N-stage prediction compared to established clinical nomograms. A clear trend towards a higher prediction of the full final as well as the additional anatomical information it yields compared to nomograms warrants further prospective evaluation for including surgical guidance.