Understanding brain-wide hemodynamic responses to different stimuli at
high spatiotemporal resolutions can help study
neuro-disorders and brain functions. However, the existing brain imaging
technologies have limited resolution, sensitivity,
imaging depth and provide information about only one or two hemodynamic
parameters. To address this, we propose a multimodal
functional ultrasound and photoacoustic (fUSPA) imaging platform, which
integrates ultrafast ultrasound and multispectral
photoacoustic imaging methods in a compact head-mountable device, to
quantitatively map cerebral blood volume (CBV),
cerebral blood flow (CBF), oxygen saturation (SO2) dynamics as well as
contrast agent enhanced brain imaging with high
spatiotemporal resolutions. After systematic characterization, the fUSPA
system was applied to quantitatively study the changes
in brain hemodynamics and vascular reactivity at single vessel
resolution in response to hypercapnia stimulation. Our results
show an overall increase in brain-wide CBV, CBF, and SO2, but regional
differences in singular cortical veins and arteries and a
reproducible anti-correlation pattern between venous and cortical
hemodynamics, demonstrating the capabilities of the fUSPA system
for providing multiparametric cerebrovascular information at
high-resolution and sensitivity, that can bring insights into the
complex mechanisms of neurodiseases.
