Improved Color Doppler for Cerebral Blood Flow Axial Velocity Imaging

Conventional color Doppler ultrasound imaging suffers from mutual frequency cancellation when applied to quantify axial blood flow velocities in the rodent brain where inverse flows exist within an ultrasound measurement voxel. Here, we report an improved color Doppler-based functional ultrasound imagingmethod (iCD-fUS) for axial blood flow velocity imaging of the rodent brain. By applying a directional filter and high frequency noise thresholding, iCD-fUS is able to accurately quantify blood flow velocities within the brain as validated with the ultrasoundlocalizationmicroscopyvelocimetrymethod. We showthat iCD-fUS is able to image and resolve the directional axial blood flowvelocity throughout the entire coronal section of the brain at a temporal frame rate of up to 10 Hz with a spatial resolution of similar to 100 mu m. We further applied iCD- fUS to image the axial blood flow velocity change in response to whisker stimulation in an awake mouse, showing its potential for studying brain activation. With these capabilities, iCD-fUS provides a powerful, quantitative tool for in vivo chronic research.

Automated summary

The improved color Doppler-based functional ultrasound imaging method (iCD-fUS) overcomes mutual frequency cancellation and accurately quantifies blood flow velocities in the rodent brain, with a spatial resolution of approximately 100 μm. iCD-fUS has the potential to study brain activation and provides a powerful, quantitative tool for in vivo chronic research.