Directional velocity estimation using focusing along the flow direction. I: Theory and simulation

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Accurate blood flow velocity estimation is crucial for diagnosing vascular diseases.
• Traditional ultrasound methods face limitations in measuring velocity in all directions, especially transverse flow.

Purpose of the Study:

• To present a new ultrasound beamforming method for directional velocity estimation.
• To evaluate the accuracy and feasibility of this method for various flow conditions and angles.

Main Methods:

• Developed a beamforming technique along the flow direction.
• Utilized cross-correlation of beamformed lines to estimate velocity from signal shifts.
• Validated the method through extensive simulations (Field II) with a 128-element, 7-MHz linear array.
• Simulated parabolic and pulsatile flow profiles under different beam-to-flow angles and transmit foci.

Main Results:

• Achieved high accuracy for velocity estimation at 45 degrees (1.6% relative standard deviation).
• Demonstrated feasibility at 90 degrees (6.6% relative standard deviation) with specific parameters.
• Successfully obtained transverse flow profiles with <10% standard deviation over the cardiac cycle for pulsatile flow.
• Simulations confirmed the ability to visualize clinically relevant transverse color flow.

Conclusions:

• The proposed method enables accurate directional velocity estimation, including transverse flow.
• This technique offers improved capabilities for ultrasound-based vascular imaging and diagnosis.
• Further development could enhance clinical applications of this advanced ultrasound velocity estimation method.