TY - JOUR AU - Bartel, Timo AU - Pabst, Kim M AU - Barg, Christina AU - Berliner, Christoph A AU - Hamacher, Rainer AU - Bauer, Sebastian AU - Falkenhorst, Johanna AU - Kessler, Lukas AU - Nader, Michael AU - Barbato, Francesco AU - Siveke, Jens AU - Herrmann, Ken AU - Fendler, Wolfgang P TI - [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. JO - Journal of nuclear medicine VL - nn SN - 0097-9058 CY - New York, NY PB - Soc. M1 - DKFZ-2025-02571 SP - nn PY - 2025 N1 - epub AB - 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 KW - 2-[18F]FDG PET/CT (Other) KW - GIST (Other) KW - [68Ga]Ga-FAPI-46 PET/CT (Other) KW - detection efficacy (Other) LB - PUB:(DE-HGF)16 C6 - pmid:41266252 DO - DOI:10.2967/jnumed.125.270850 UR - https://inrepo02.dkfz.de/record/306359 ER -