RT Journal Article SR Electronic T1 FAP-ligands and uterine fibroids: subsidiary findings in cancer imaging JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 3096 OP 3096 VO 63 IS supplement 2 A1 Dendl, Katharina A1 Koerber, Stefan A. A1 Finck, Rebecca A1 Tamburini, Katharina A1 Staudinger, Fabian A1 Kratochwil, Clemens A1 Debus, Jürgen A1 Haberkorn, Uwe A1 Giesel, Frederik YR 2022 UL http://jnm.snmjournals.org/content/63/supplement_2/3096.abstract AB 3096 Introduction: Fibroblast activation protein (FAP) is upregulated by cancer associated fibroblasts and, thereby, mainly elevated in neoplastic tissue. However, FAP is also overexpressed during tissue remodeling, at sites of inflammation, wound healing and non-malignant diseases. Hence, we sought to evaluate the phenomenon of uterine fibroides induced uptake in oncological patients receiving 68Ga-FAPI-PET/CT.Methods: This retrospective preliminary analysis comprises 16 cancer patients with uterine fibroides undergoing 68Ga-FAPI-PET/CT. Quantification of tracer uptake was determined based on standardized uptake values (SUVmean and SUVmax). Furthermore, the uteri of 95 women within a similar age range were measured in order to establish a referential physiological uptake. Results: The evaluation determined a considerably high mean SUVmean of 6.4 and SUVmax of 11.7. The referential physiological uptake (n=95; range 47-77y) presented significantly lower mean uptake in terms of SUVmean (1.9; p<0.0001) and SUVmax (3.1; p<0.0001) compared to tracer accumulation in patients with uterine fibroides. Conclusions: This preliminary investigation of FAPI accumulation in benign lesions clearly reveales uterine fibroides as subsidiary findings. These identified lesions presented significantly higher tracer uptake than the established referential physiologic standard. The knowledge of tracer accumulation in benign conditions is critical to assure accurate interpretation of FAPI-PET/CT scans and therefore, urgently requires further (cross)-validation.