In Vivo Functional Ultrasound (fUS) Real-Time Imaging and Dosimetry of Mice Brain Under Radiofrequency Exposure

Abstract

Overview

This study is focused on examining the real-time impact of radiofrequency (RF) exposure on brain activation in anesthetized mice. The RF sources include low-level continuous-wave and Global System for Mobile Communications at a frequency of 1.8 GHz.

Methodology

• A specialized in vivo setup using a dipole antenna for targeted brain exposure was fully characterized.
• A functional ultrasound (fUS) probe was employed to concurrently observe brain activation with unparalleled spatial (~100 μm) and temporal (1 ms) resolution during RF exposure.
• Manual whisker stimulation with a brush was used to activate specific brain regions.
• Both numerical and experimental dosimetry were conducted to ensure the accuracy of exposure settings and the reliability of biological outcomes.

Findings

The study successfully demonstrated that the fUS probe can be used effectively during RF exposure without technical interference. Brain-averaged specific absorption rates of 2 and 6 W/kg did not significantly alter the evoked fUS responses in the left barrel field cortex.

Conclusion

The new imaging technique has provided crucial insights into the potential effects of RF exposure on brain activity, marking a significant advancement in the field. Notably, this is the first in vivo evaluation of brain activity under mobile phone radiation using fUS imaging, setting a foundation for future studies with awake subjects and potential implications for 5G network exposures.