Noninvasive photoacoustic computed mesoscopy for longitudinal brain imaging

Area of Science:

• Neuroimaging
• Biomedical Optics
• Medical Physics

Background:

• Photoacoustic imaging offers powerful visualization of brain morphology, function, and metabolism.
• Optical scattering and acoustic attenuation in the brain limit current photoacoustic imaging performance.
• Noninvasive, high-resolution, longitudinal brain imaging is crucial for understanding brain function and disease.

Purpose of the Study:

• To develop and validate a novel photoacoustic computed mesoscopic (PACMes) approach for noninvasive, high-resolution, longitudinal visualization of cerebral vasculature in the intact mouse brain.
• To overcome the limitations of optical scattering and acoustic attenuation in deep brain imaging.
• To enable long-term monitoring of brain vasculature for disease research.

Main Methods:

• Utilized a line scanning-based photoacoustic computed mesoscopic (PACMes) technique.
• Employed converging near-infrared (NIR) lines scanned at multiple angles for efficient optical excitation.
• Integrated a low-frequency, full-ring ultrasound transducer array for sensitive signal detection.
• Applied a compound reconstruction algorithm combining filtered back-projection and optical localization for image recovery.

Main Results:

• Achieved noninvasive, longitudinal imaging of the entire mouse cortex through intact scalp and skull for over 5 months.
• Demonstrated a field of view of 13 millimeters with a spatial resolution of 33 micrometers.
• Successfully visualized cerebral vasculature with high resolution and sensitivity.

Conclusions:

• The PACMes approach provides a powerful tool for noninvasive, high-resolution, and longitudinal visualization of the intact mouse brain vasculature.
• This technique addresses key limitations in current photoacoustic brain imaging, paving the way for advanced neuroscience research.
• PACMes holds significant potential for investigating brain function, development, and disease progression in vivo.