Navigating the Scoring Systems and Interpretation Frameworks of Prostate-specific Membrane Antigen PET

Prostate-specific membrane antigen (PSMA) PET is a powerful tool for prostate cancer staging and restaging, providing higher sensitivity and specificity than conventional imaging. The recognition of interpretive pitfalls led to the development of various scoring systems and frameworks, which in turn created challenges for consistent interpretation. The Prostate Cancer Molecular Imaging Standardized Evaluation (PROMISE) version 2 classification integrates the five-point PRIMARY score for assessing local disease, the molecular imaging TNM stage for disease extent, and the PSMA expression score to assess eligibility for PSMA-targeted radioligand therapy. The PSMA Reporting and Data System (PSMA-RADS) classifies PSMA PET/CT findings on the basis of the likelihood of presence of prostate cancer. For assessing therapy response, PSMA PET Progression (PPP) criteria focus on new lesions and clinical or biochemical progression, whereas Response Evaluation Criteria in PSMA PET/CT (RECIP 1.0) assess new lesions and changes in total PSMA-positive total tumor volume. The European Association of Nuclear Medicine (EANM) E-PSMA guideline and EANM-Society of Nuclear Medicine and Molecular Imaging procedure guidelines provide standardized reporting recommendations, incorporating elements from existing systems such as PROMISE, PSMA-RADS, and PPP. Nevertheless, such systems can be essential for optimizing prostate cancer management and facilitating communication among imaging professionals, clinicians, and patients. This article outlines these systems and discusses potential strengths and weaknesses.