%0 Journal Article %A Bartel, Timo %A Pabst, Kim M %A Barg, Christina %A Berliner, Christoph A %A Hamacher, Rainer %A Bauer, Sebastian %A Falkenhorst, Johanna %A Kessler, Lukas %A Nader, Michael %A Barbato, Francesco %A Siveke, Jens %A Herrmann, Ken %A Fendler, Wolfgang P %T [68Ga]Ga-FAPI-46 PET/CT of Patients with Gastrointestinal Stromal Tumors in Comparison to 2-[18F]FDG PET/CT and Contrast-Enhanced CT: Results from a Prospective Observational Study. %J Journal of nuclear medicine %V nn %@ 0097-9058 %C New York, NY %I Soc. %M DKFZ-2025-02571 %P nn %D 2025 %Z epub %X Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Although contrast-enhanced CT (ceCT) and 2-[18F]FDG PET/CT remain standard imaging modalities, both exhibit limitations in detecting small peritoneal metastases and tumors with low metabolic activity. 68Ga-labeled fibroblast activation protein inhibitors (FAPIs) have shown promising results in various malignancies; however, comparative data on GISTs are limited. This study aimed to assess the diagnostic performance of [68Ga]Ga-FAPI-46 PET/CT in comparison with 2-[18F]FDG PET/CT and ceCT, including evaluation of interreader reproducibility and clinical impact. Methods: This study retrospectively reviewed 25 patients with histopathologically confirmed GISTs undergoing [68Ga]Ga-FAPI-46 PET/CT as part of a prospective observational study (NCT04571086). All patients (n = 25) underwent additional clinical 2-[18F]FDG PET/CT; ceCT was performed for 23 of 25 patients. Imaging was assessed per patient and per region (primary tumor, lymph nodes, and visceral and bone metastases), and a composite reference standard that included histopathology, follow-up imaging, and clinical data was applied. Interreader agreement, stratified by experience level, was analyzed using Cohen κ (κCohen). Referring physicians completed questionnaires before and after imaging to determine clinical impact. Results: In total, 28 validated regions (n = 20 patients) were included in the diagnostic efficacy analysis. Per region, ceCT and [68Ga]Ga-FAPI-46 PET/CT demonstrated comparable sensitivity (83 %K 2-[18F]FDG PET/CT (Other) %K GIST (Other) %K [68Ga]Ga-FAPI-46 PET/CT (Other) %K detection efficacy (Other) %F PUB:(DE-HGF)16 %9 Journal Article %$ pmid:41266252 %R 10.2967/jnumed.125.270850 %U https://inrepo02.dkfz.de/record/306359