Quantitative pulsatility measurements using 3D dynamic ultrasound localization microscopy.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Increased brain blood flow pulsatility is linked to cognitive decline and neurodegenerative diseases.
• Accurate measurement requires high-resolution, brain-wide imaging with deep penetration.
• Previous 2D methods provided limited, biased velocity data.

Purpose of the Study:

• To develop and validate a 3D dynamic ultrasound localization microscopy (DULM) method for quantitative brain pulsatility measurement.
• To assess microvascular hemodynamics in large and small brain vessels in vivo.
• To establish a potential new biomarker for early detection of neurodegenerative diseases.

Main Methods:

• Utilized a single ultrasound scanner operating at high frame rates (1000-2000 Hz).
• Generated dynamic microbubble flow maps to extract quantitative pulsatility.
• Applied the technique to both explanted cat brains and skull-intact mouse brains.

Main Results:

• Achieved 3D quantitative pulsatility mapping in the cat and mouse brain.
• Observed pulsatility decrease along the vascular tree in the cat brain, visualized down to tens of micrometers.
• Demonstrated intra-animal measurement consistency in the mouse brain's Circle of Willis.

Conclusions:

• 3D DULM enables unprecedented 3D visualization and quantification of brain microvascular pulsatility.
• The method reveals detailed hemodynamic patterns across the cerebrovasculature.
• This technique represents a significant advancement towards a novel biomarker for early neurodegenerative disease detection.