Characterizing Normal Variant [⁶⁸Ga]Ga-FAPI-46 Uptake in the Epididymis

Area of Science:

• Nuclear Medicine
• Radiopharmacy
• Oncology Imaging

Background:

• Fibroblast activation protein inhibitor (FAPI) PET tracers are increasingly used for imaging.
• Known biodistribution includes kidneys, bladder, uterus, breast, muscles, and bone marrow.
• Occasional uptake patterns in the epididymis require further investigation.

Purpose of the Study:

• To analyze the uptake patterns of [68Ga]Ga-FAPI-46 in the epididymis.
• To determine if epididymal uptake is associated with epididymal disease.

Main Methods:

• Retrospective analysis of 55 PET/CT studies in 55 men.
• Evaluation of epididymal [68Ga]Ga-FAPI-46 uptake intensity (SUV), pattern, laterality, and location.
• Review of electronic medical records to assess for epididymis-related disease.

Main Results:

• Epididymal [68Ga]Ga-FAPI-46 uptake was observed in 15% of subjects.
• Uptake was predominantly in the epididymal head, with some cases showing body/tail involvement.
• No association was found between epididymal uptake and epididymal disease.

Conclusions:

• [68Ga]Ga-FAPI-46 uptake in the epididymis is an occasional finding.
• This uptake does not indicate the presence of epididymal disease.