FAPI-04 Uptake in Healthy Tissues of Cancer Patients in 68Ga-FAPI-04 PET/CT Imaging

Objective. The aim of this study is to investigate the uptake of 68Ga-FAPI-04 in normal tissues and calculate standardized uptake values (SUVs) for various organs in the body. Methods. A total of 49 patients who underwent 68Ga-FAPI-04 PET/CT were included in our study. The following organs were identified on CT images: brain, parotid, and submandibular glands, palatine tonsils, thyroid, lymph nodes (if present), breasts, lungs, thymus, left ventricle walls, mediastinal blood pool, vertebral bone marrow, liver, spleen, pancreas, stomach, small and large intestines, adrenal glands, kidneys, uterus, testes, and prostate. Median, minimum, and maximum values (max) and average (avg) values of standard uptake value (SUV) of tissues and organs were calculated. Results. The accumulation of 68Ga-FAPI in normal organs showed variations. The cerebral/cerebellar cortex exhibited no 68Ga-FAPI uptake, while the scalp showed low uptake. Low uptake was also observed in the lung parenchyma, esophagus, left ventricle walls, nipple, and glandular breast tissue. In the abdominopelvic area, the pancreas exhibited low uptake, which was higher in the tail region. Low uptake was observed in the renal cortex. Intense 68Ga-FAPI uptake was observed throughout the uterus, which was higher in the corpus. There was no uptake of 68Ga-FAPI in the bone cortex and medulla. Conclusion. We determined the physiological uptake and SUVmax of FAPI-04 in different tissues and organs and created a guide for researchers.