Perineural Involvement and Lung Metastasis From Hormone-Sensitive Prostate Cancer: Multimodal Imaging With MRI and Dual-tracer PSMA/[18F]FDG PET/CT

A 66-year-old man with a history of high-grade prostate cancer (PCa), treated with prostatectomy and radiotherapy, experienced rising prostate-specific antigen (PSA) levels and lumbar pain that was unresponsive to analgesics. Magnetic Resonance Imaging (MRI) showed pathological thickening and enhancement of the left S1-S3 nerve roots, as well as an intradural nodule. PET/CT with [18F]F-PSMA-1007 revealed increased uptake in the sacral nerves and a PSMA-negative lung nodule. A subsequent [18F]FDG PET/CT showed FDG uptake in both the sacral plexus and the lung nodule, suggesting diffusely metastatic PCa. In the case we describe, multimodal imaging with MRI and dual-tracer PET/CT was essential to obtain a comprehensive view of tumor extension and biology.