Functional transcranial brain imaging by optical-resolution photoacoustic microscopy

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optical Imaging

Background:

• Functional brain imaging is crucial for understanding neurological disorders.
• Existing methods often lack the resolution to study capillary-level hemodynamics.
• In vivo imaging of microvasculature and oxygenation remains a challenge.

Purpose of the Study:

• To develop and apply optical-resolution photoacoustic microscopy (OR-PAM) for high-resolution functional brain imaging in living mice.
• To visualize brain microvascular morphology and map hemoglobin oxygen saturation (sO(2)) non-invasively.
• To establish a foundation for studying neurovascular coupling and brain metabolism.

Main Methods:

• Utilized near-diffraction-limited bright-field optical illumination for micrometer lateral resolution.
• Employed dual-wavelength photoacoustic measurements to extract blood oxygenation information.
• Performed in vivo volumetric imaging through intact mouse skulls.

Main Results:

• Achieved micrometer-scale resolution imaging of brain microvasculature in living mice.
• Successfully mapped hemoglobin oxygen saturation (sO(2)) variations along arteriolar and venular trees.
• Demonstrated the first in vivo volumetric imaging of single capillaries and their oxygenation status in the mouse brain.

Conclusions:

• OR-PAM offers a minimally invasive approach for chronic functional brain imaging.
• This technique can advance the study of cortical plasticity and neurological diseases.
• Findings facilitate understanding of neurovascular coupling and brain energy metabolism at the capillary level.