Ultrasound Image Velocimetry for High Spatiotemporal Resolution Blood Flow Velocity Field Mapping in Mice

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Medical Imaging

Background:

• Abnormal hemodynamics are crucial in cardiovascular disease development.
• Mouse models are vital for research but pose challenges for high-resolution flow mapping due to size and heart rate.
• Existing methods struggle with the temporal resolution needed for quantitative flow velocity field mapping in small animal models.

Purpose of the Study:

• To develop a noninvasive method for quantitative flow field mapping in mice.
• To utilize speckle-tracking from high-frequency ultrasound B-mode imaging.
• To overcome limitations in temporal resolution for mouse cardiovascular studies.

Main Methods:

• Ultrasound ECG-gated kilohertz visualization (EKV) was used on a flow phantom at up to 10,000 fps.
• Simulations and in silico ultrasound image velocimetry (UIV) identified velocity underestimations.
• An error correction technique was developed, validated in vitro, and tested in vivo.

Main Results:

• EKV-UIV showed 50%-70% velocity underestimation in flow phantoms due to speckle contiguity loss.
• The correction technique reduced errors to <10% by analyzing speckle movement within image strips.
• In vivo studies demonstrated improved alignment of mouse left ventricle vortex shapes and near-wall movement with physical models after correction.

Conclusions:

• A novel technique for quantitative blood flow mapping with high spatiotemporal resolution was developed.
• This method offers potential for improved understanding of hemodynamic forces in cardiovascular disease.
• Further optimization could facilitate longitudinal studies in mouse models.