Physiologic prostate-specific membrane antigen-targeted 18F-DCFPyL uptake in the epididymis head newly appreciated on digital PET/CT.

The published physiological distribution of prostate-specific membrane antigen (PSMA) PET ligands includes normal uptake in the lacrimal glands, salivary glands, bowel, liver, spleen, kidneys and parasympathetic ganglia but does not include the epididymis. Using a latest-generation digital PET scanner, we report physiologic PSMA radiotracer uptake in the epididymal head region as a new physiological variant presented in a case series of 134 PSMA-targeted 2-(3-(1-carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid (18F-DCFPyL) PET/computed tomography (CT) scans. The high spatial resolution of digital PET/CT is the most likely explanation for the apparent 'novelty' of this epididymal normal variant, which is associated with higher serum testosterone levels.