Test–retest repeatability of organ uptake on PSMA‐targeted ¹⁸F‐DCFPyL PET/CT in patients with prostate cancer

Abstract

Objectives We evaluated 18F‐DCFPyL test–retest repeatability of uptake in normal organs. Methods Twenty‐two prostate cancer (PC) patients underwent two 18F‐DCFPyL PET scans within 7 days within a prospective clinical trial (NCT03793543). In both PET scans, uptake in normal organs (kidneys, spleen, liver, and salivary and lacrimal glands) was quantified. Repeatability was determined by using within‐subject coefficient of variation (wCOV), with lower values indicating improved repeatability. Results For SUVmean, repeatability was high for kidneys, spleen, liver, and parotid glands (wCOV, range: 9.0%–14.3%) and lower for lacrimal (23.9%) and submandibular glands (12.4%). For SUVmax, however, the lacrimal (14.4%) and submandibular glands (6.9%) achieved higher repeatability, while for large organs (kidneys, liver, spleen, and parotid glands), repeatability was low (range: 14.1%–45.2%). Conclusion We found acceptable repeatability of uptake on 18F‐DCFPyL PET for normal organs, in particular for SUVmean in the liver or parotid glands. This may have implications for both PSMA‐targeted imaging and treatment, as patient selection for radioligand therapy and standardized frameworks for scan interpretation (PROMISE, E‐PSMA) rely on uptake in those reference organs.

Salivary excretion of systemically injected [18F]DCFPyL in prostate cancer patients undergoing PSMA scans

“…Prostate-specific membrane antigen (PSMA) is overexpressed in prostate cancer (PC). Studies using PSMA-binding agents, such as 2-(3-{1-carboxy-5-[(6-[ 18 F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid ([ 18 F]-DCFPyL), have demonstrated high uptake and retention of this agent in salivary glands ( 1 , 2 ). While salivary uptake of imaging agents has minimal clinical impact, the clinical implication for salivary gland damage is much more important when PSMA-targeting therapeutic agents are used for targeted radionuclide therapy (TRT) ( 3 ).…”