Comparison between pelvic PSMA-PET/MR and whole-body PSMA-PET/CT for the initial evaluation of prostate cancer: a proof of concept study
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Despite the advantages of prostate-specific membrane antigen (PSMA)-PET/MR over PSMA-PET/CT, its relatively long scanning time and suboptimal PET attenuation correction necessitate careful assessment of the most appropriate setting for this type of study. We assessed lesion agreement between PSMA-PET/MR and PSMA-PET/CT in patients undergoing initial evaluation of prostate cancer.
This was a prospective study of consecutive patients with histological biopsy-proven prostate cancer who underwent pelvic PSMA-PET/MR followed by whole-body PSMA-PET/CT. All conspicuous PSMA-avid foci were counted on PSMA-PET/CT and PSMA-PET/MR with CT or MR correlation. Analysis was performed for intra-prostatic lesions, capsular invasion, seminal vesicle involvement and lymph node and bone involvement. Incidental and significant findings seen on PSMA-PET/CT outside the PSMA-PET/MR field of view were also analysed. Agreements between PSMA-PET/CT and PSMA-PET/MR findings were performed using Cohen’s kappa test.
Image analysis was performed on 140 patients (mean age, 67.3 ± 8.2 years). Agreement between PSMA PET/CT and PSMA-PET/MR was very good for intra-prostatic PSMA-avid foci (K = 0.85) and pelvic lymph nodes (K = 0.98), good for PSMA-avid bone metastases (K = 0.76) and fair for prostatic capsular invasion (K = 0.25) and seminal vesicle involvement (K = 0.31). Twelve patients (8.5%) had incidental findings and two patients (1.4%) had clinically significant findings.
Limited pelvic PSMA-PET/MR has very good agreement with PET/CT regarding PSMA-avid prostatic, regional lymph nodes and bone lesions, and is superior to PET/CT with regard to capsular invasion and seminal vesicle involvement.
• Limited pelvic PSMA-PET/MR is superior to whole-body PSMA-PET/CT in detecting extensions of localised disease, mainly due to the high soft tissue resolution of MR.
• Limited pelvic PSMA-PET/MR may be useful for initial evaluation of histological biopsy-proven prostate cancer.
• Further studies are warranted to evaluate limited pelvic PSMA-PET/MR for screening and active surveillance in selected populations.
KeywordsProstate cancer Prostate-specific membrane antigen PET/MR PET/CT
Field of view
Multi-parametric magnetic resonance imaging
Ordered subset expectation maximisation
Positron emission tomography
Prostate Imaging-Reporting and Data System
Prostate-specific membrane antigen
The authors acknowledge Zohar Nitsan, Inbal Machcat and Hagai Baruch for their excellent work in patient scanning, Dr. Limor Shaharabani-Gargir for patient management and Dr. Sharon Furman-Assaf for editing.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Prof. David Groshar.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors (Meital Nidam) has significant statistical expertise.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
• Diagnostic or prognostic study
• Performed at one institution
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