Evaluating mpMRI and PSMA-targeted PET/CT for Radiorecurrent Prostate Cancer

A recent narrative review in Frontiers in Oncology examines the diagnostic roles of multiparametric MRI (mpMRI) and PSMA-targeted PET/CT in patients experiencing biochemical relapse of prostate cancer following radiotherapy. Understanding these imaging modalities is critical for accurately restaging patients eligible for targeted local salvage treatments versus those needing systemic approaches.

The review synthesized data from ten studies, comprising both retrospective and prospective analyses. Findings indicate that mpMRI is associated with variable sensitivity, particularly for intraprostatic recurrences, with a specificity range of 64% to 87%. This variance is largely attributed to inadequacies in detecting multifocal diseases post-brachytherapy, a common radiation therapy for prostate cancer.

In contrast, PSMA-targeted PET/CT demonstrated high sensitivity, approximately up to 89%, in identifying intraprostatic recurrences and was particularly effective in spotting distant metastases—an advantage over mpMRI. However, its limit lies in detecting very small lesions or those with low PSMA expression, which could lead to diagnostic ambiguity.

The combined use of mpMRI and PSMA-targeted PET/CT has emerged as a superior diagnostic strategy, boasting a positive predictive value of 97.6% when findings from both imaging modalities are consistent. This integrative approach allows for heightened diagnostic confidence, thus refining patient selection for appropriate salvage therapy.

Upon examination of the post-brachytherapy scenario, mpMRI encountered significant challenges in lesion visibility due to radiation artifacts, leading to missed detections and underestimated diagnoses. On the other hand, PSMA-targeted PET/CT has shown resilience in maintaining diagnostic performance post-brachytherapy, further corroborating its utility in comprehensive disease mapping.

In conclusion, the review highlights that mpMRI and PSMA-targeted PET/CT contribute complementary insights into the management of radiorecurrent prostate cancer. While neither method singularly assures comprehensive detection, their combined application significantly bolsters the precision and scope of restaging efforts, aiding in the formulation of tailored treatment and intervention strategies. Accurate imaging thus plays a pivotal role in determining the most suitable management pathway for patients facing prostate cancer recurrence post-radiotherapy.