Initial clinical experience using Ga-FAPI-46 PET/CT 68 for detecting various cancer types

Objective: Numerous studies have shown that gallium-68-labeled fibroblast activation protein inhibitor ( Ga-FAPI) positron emission tomography/computed tomography (PET/CT) scans would yield high intratumoral tracer uptake and low uptake in normal tissues as background, thus allowing for excellent visualization of lesions in the cancer micro environment. This study set out to compare the suit ability of novel 68Ga-FAPI-46 PET versus routine fluorine-18-fluorodeoxyglucose (F-FDG) PET and otherfew cases of GaDOTATATE/ Ga-Pentixa for PET/CT for the assessment of differenttypesofcancer.SubjectsandMethods: A retrospective analysis of 11 patients (6 males, 5 females; average age: 53 years, range: 10-58 years) with histopathologically confirmed, well-differentiated adenocarcinoma, medullar thyroid cancer (MTC), papillary thyroid carcinoma (PTC), cervical, gastric, glioblastoma multiform (GBM), colon, Ewing's sarcoma, and breast cancer was performed. These patients underwent PET/CT scans using four different radio-tracers(9F-FDG,11 Ga-FAPI,3Ga-DOTATATE, and 1 Ga-Pentixafor). The patients' PET/CT images were visually evaluated for cancer detection, and analyzed semi-quantitatively through image-derived metrics, such as target-to-background ratio (TBR) and maximum standardized uptake value (SUVmax), for recurrence and metastasis. Results:The study of 11 patients revealed that Ga-FAPI-46 was more eective than other tracers for detecting metastases, with 55 vs. 49 metastases in the lymph nodes, 4 vs. 3 in the liver, and 4 vs. 3 in the bones detected in comparison toF-FDG. No significant differences were observed in GaDOTATATE and Ga-Pentixafor PET images. In addition, in five patients, the SUVmax and TBR values in GaFAPI-46 PET images were significantly higher than those in F-FDG PET images for lymph nodes and bone metastases. Although the SUVmax in Ga-FAPI-46 and F-FDG PET images for liver metastases was comparable, Ga-FAPI-46 had a significantly higher TBR than F-FDG. Conclusions: Ourfindings suggestthat FAPI PET/CT is not suitable for evaluating GBM and Ewing sarcoma but generally outperforms F-FDG PET/CT in various types of breast cancer, gastrointestinal, gynecological, PTC and MTC. However, larger trials are needed to validate these preliminaryfindings.