A Comparative pO2 Probe and [18F]-Fluoro-Azomycinarabino-Furanoside ([18F]FAZA) PET Study Reveals Anesthesia-Induced Impairment of Oxygenation and Perfusion in Tumor and Muscle.

Tumor hypoxiacan be identified by [18F]FAZA positron emission tomography, or invasively using oxygen probes. The impact of anesthetics on tumor hypoxiaremains controversial. The aim of this comprehensive study was to investigate the impact of isofluraneand ketamine/ xylazineanesthesia on [18F]FAZA uptake and partial oxygen pressure (pO2) in carcinoma and muscle tissueof air- and oxygen-breathing mice. Methods CT26 colon carcinoma-bearing mice were anesthetized with isoflurane(IF) or ketamine/ xylazine(KX) while breathing air or oxygen (O2). We performed 10 min static PET scans 1 h, 2 h and 3 h after [18F]FAZA injection and calculated the [18F]FAZA-uptake and tumor-to-muscle ratios (T/M). In another experimental group, we placed a pO2 probe in the tumor as well as in the gastrocnemius muscleto measure the pO2 and perfusion.