Imaging of Tumor Hypoxia With 18F-EF5 PET/MRI in Cervical Cancer.

PURPOSE OF THE REPORT: The aim of this study was to evaluate the distribution of hypoxia using 18F-EF5 as a hypoxia tracer in cervical cancer patients with PET/MRI. We investigated the association between this 18F-EF5-PET tracer and the immunohistochemical expression of endogenous hypoxia markers: HIF1α, CAIX, and GLUT1. PATIENTS AND METHODS: Nine patients with biopsy-proven primary squamous cell cervix carcinoma (FIGO 2018 radiological stages IB1-IIIC2r) were imaged with dual tracers 18F-EF5 and 18F-FDG using PET/MRI (Int J Gynaecol Obstet. 2019;145:129-135). 18F-EF5 images were analyzed by calculating the tumor-to-muscle ratio to determine the hypoxic tissue (T/M ratio >1.5) and further hypoxic subvolume (HSV) and percentage hypoxic area. These 18F-EF5 hypoxic parameters were correlated with the size and localization of tumors in 18F-FDG PET/MRI and the results of hypoxia immunohistochemistry. RESULTS: All primary tumors were clearly 18F-FDG and 18F-EF5 PET positive and heterogeneously hypoxic with multiple 18F-EF5-avid areas in locally advanced cancer and single areas in clinically stage I tumors. The location of hypoxia was detected mainly in the periphery of tumor. Hypoxia parameters 18F-EF5 max T/M ratio and HSV in primary tumors correlated independently with the advanced stage (P = 0.036 and P = 0.040, respectively), and HSV correlated with the tumor size (P = 0.027). The location of hypoxia in 18F-EF5 imaging was confirmed with a higher hypoxic marker expression HIF1α and CAIX in tumor fresh biopsies. CONCLUSIONS: The 18F-EF5 imaging has promising potential in detecting areas of tumor hypoxia in cervical cancer.

Catalytic decarboxylative fluorination for the synthesis of tri- and difluoromethyl arenes.

Treatment of readily available α,α-difluoro- and α-fluoroarylacetic acids with Selectfluor under Ag(I) catalysis led to decarboxylative fluorination. This operationally simple reaction gave access to tri- and difluoromethylarenes applying a late-stage fluorination strategy. Translation to [(18)F]labeling is demonstrated using [(18)F]Selectfluor bis(triflate), a reagent affording [(18)F]tri- and [(18)F]difluoromethylarenes not within reach with [(18)F]F2.

[18F]fluorination of an arylboronic ester using [18F]selectfluor bis(triflate): application to 6-[18F]fluoro-L-DOPA.

The Ag-mediated electrophilic [(18)F]fluorination of an arylboronic ester is reported. This new radiochemical transformation uses [(18)F]selectfluor bis(triflate) in acetone. The process gave 6-[(18)F]fluoro-L-DOPA with a RCY of 19 ± 12% and a specific activity of 2.6 ± 0.3 GBq µmol(-1).