biostudies-literatureTuominen STurku University FoundationSvenska KulturfondenFinnish Governmental Research Funding for Turku University Hospital1312-1326https://www.ebi.ac.uk/biostudies/studies/S-EPMC8113193biostudies-literatureUnknown48(5)<h4>Background</h4>Many malignant tumours have increased TSPO expression, which has been related to a poor prognosis. TSPO-PET tracers have not comprehensively been evaluated in peripherally located tumours. This study aimed to evaluate whether N,N-diethyl-2-(2-(4-([¹⁸F]fluoro)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide ([¹⁸F]F-DPA) can reflect radiotherapy (RT)-induced changes in TSPO activity in head and neck squamous cell carcinoma (HNSCC).<h4>Methods</h4>RT was used to induce inflammatory responses in HNSCC xenografts and cells. [¹⁸F]F-DPA uptake was measured in vivo in non-irradiated and irradiated tumours, followed by ex vivo biodistribution, autoradiography, and radiometabolite analysis. In vitro studies were performed in parental andEuropean journal of nuclear medicine and molecular imagingEvaluation of [¹⁸F]F-DPA as a target for TSPO in head and neck cancer under normal conditions and after radiotherapy.PMC811319326098213142139742Rajander JKeller TLoyttyniemi ESandholm JTuominen SPetruk NTuomela JLopez-Picon FEichin DVerhassel AGronroos TJfalseEvaluation of [¹⁸F]F-DPA as a target for TSPO in head and neck cancer under normal conditions and after radiotherapy.<h4>Background</h4>Many malignant tumours have increased TSPO expression, which has been related to a poor prognosis. TSPO-PET tracers have not comprehensively been evaluated in peripherally located tumours. This study aimed to evaluate whether N,N-diethyl-2-(2-(4-([¹⁸F]fluoro)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide ([¹⁸F]F-DPA) can reflect radiotherapy (RT)-induced changes in TSPO activity in head and neck squamous cell carcinoma (HNSCC).<h4>Methods</h4>RT was used to induce inflammatory responses in HNSCC xenografts and cells. [¹⁸F]F-DPA uptake was measured in vivo in non-irradiated and irradiated tumours, followed by ex vivo biodistribution, autoradiography, and radiometabolite analysis. In vitro studies were performed in parental and2021-01-01T00:00:00Z2021 May2026-04-18T01:36:16.209Z2022-02-10T10:21:17.367ZS-EPMC81131933334005410.1007/s00259-020-05115-z