68Ga-PSMA-11 PET/MRI versus multiparametric MRI in men referred for prostate biopsy: primary tumour localization and interreader agreement.

Magnetic resonance imaging (MRI) is recommended by the European Urology Association guidelines as the standard modality for imaging-guided biopsy. Recently positron emission tomography with prostate-specific membrane antigen (PSMA PET) has shown promising results as a tool for this purpose. The aim of this study was to compare the accuracy of positron emission tomography with prostate-specific membrane antigen/magnetic resonance imaging (PET/MRI) using the gallium-labeled prostate-specific membrane antigen (68Ga-PSMA-11) and multiparametric MRI (mpMRI) for pre-biopsy tumour localization and interreader agreement for visual and semiquantitative analysis. Semiquantitative parameters included apparent diffusion coefficient (ADC) and maximum lesion diameter for mpMRI and standardized uptake value (SUVmax) and PSMA-positive volume (PSMAvol) for PSMA PET/MRI.

Sensitivity and specificity were 61.4% and 92.9% for mpMRI and 66.7% and 92.9% for PSMA PET/MRI for reader one, respectively. RPE was available in 23 patients and 41 of 47 quadrants with discrepant findings. Based on RPE results, the specificity for both imaging modalities increased to 98% and 99%, and the sensitivity improved to 63.9% and 72.1% for mpMRI and PSMA PET/MRI, respectively. Both modalities yielded a substantial interreader agreement for primary tumour localization (mpMRI kappa = 0.65 (0.52-0.79), PSMA PET/MRI kappa = 0.73 (0.61-0.84)). ICC for SUVmax, PSMAvol and lesion diameter were almost perfect (≥ 0.90) while for ADC it was only moderate (ICC = 0.54 (0.04-0.78)). ADC and lesion diameter did not correlate significantly with Gleason score (ρ = 0.26 and ρ = 0.16) while SUVmax and PSMAvol did (ρ =  - 0.474 and ρ =  - 0.468).

PSMA PET/MRI has similar accuracy and reliability to mpMRI regarding primary prostate cancer (PCa) localization. In our cohort, semiquantitative parameters from PSMA PET/MRI correlated with tumour grade and were more reliable than the ones from mpMRI.

European journal of hybrid imaging. 2022 Jul 18*** epublish ***

Daniela A Ferraro, Andreas M Hötker, Anton S Becker, Iliana Mebert, Riccardo Laudicella, Anka Baltensperger, Niels J Rupp, Jan H Rueschoff, Julian Müller, Ashkan Mortezavi, Marcelo T Sapienza, Daniel Eberli, Olivio F Donati, Irene A Burger

Department of Nuclear Medicine, University Hospital Zürich, University of Zurich, Rämistrasse 100, 8091, Zurich, Switzerland., Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland., Department of Pathology and Molecular Pathology, University Hospital Zurich, University of Zurich, Zurich, Switzerland., Department of Urology, University Hospital Zürich, University of Zurich, Zurich, Switzerland., Department of Radiology and Oncology, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, Brazil., Department of Nuclear Medicine, University Hospital Zürich, University of Zurich, Rämistrasse 100, 8091, Zurich, Switzerland. .

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