PSMA ligand PET/MRI for primary prostate cancer: Staging performance and clinical impact

Purpose: Primary staging of prostate cancer (PC) relies on modalities, which are limited. We evaluate simultaneous [⁶⁸Ga]Ga-PSMA-11positron emission tomography (PSMA-PET)/magnetic resonance imaging (MRI) as a new diagnostic method for primary TNM-staging compared to histology and its impact on therapeutic decisions. Patients and Methods: We investigated 122 patients with PSMA-PET/MRI prior to planned radical prostatectomy (RP). Primary endpoint was the accuracy of PSMA-PET/MRI in tumor staging as compared to staging-relevant histology. Additionally, a multidisciplinary team reassessed the initial therapeutic approach to evaluate its impact on the therapeutic management. Results: PSMA-PET/MRI correctly identified PC in 119 of 122 patients (97.5%). 81 patients were treated with RP and pelvic lymphadenectomy. The accuracy for T-staging was 82.5% (95%CI 73-90; P<0.001), for T2-stage: 85% (95%CI 71-94; P<0.001), T3a-stage: 79% (95%CI 43-85; P<0.001), T3b-stage: 94% (95%CI 73-100; P<0.001) and 93% (95%CI 84-98) for N1-stage (P<0.001). PSMA-PET/MRI changed the therapeutic strategy in 28.7% of the patients with either the onset of systemic therapy/radiotherapy (n=16) or active surveillance (n=19). Conclusion: PSMA-PET/MRI can provide an accurate staging of newly diagnosed PC. Additionally, treatment strategies were changed in almost a third of the patients due to the information of this hybrid imaging technique.

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