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

Abstract

Objectives: We evaluated ¹⁸ F-DCFPyL test-retest repeatability of uptake in normal organs.

Methods: Twenty-two prostate cancer (PC) patients underwent two ¹⁸ F-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 SUV_mean , 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 SUV_max , 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 ¹⁸ F-DCFPyL PET for normal organs, in particular for SUV_mean 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.

Keywords: 18F-DCFPyL; E-PSMA; PROMISE; PSMA-PET/CT; organ uptake; prostate cancer; radioligand therapy; theranostics.