Spread-Spectrum Beamforming and Clutter Filtering for Plane-Wave Color Doppler Imaging

Area of Science:

• Ultrasound medical imaging
• Doppler ultrasonography
• Signal processing in medical imaging

Background:

• Plane-wave imaging offers high frame rates for dynamic events but compounding degrades Doppler signals.
• Compounding in plane-wave imaging limits Doppler frequency and frame rate due to slow-time low-pass filtering.
• Existing methods face a trade-off between image resolution, Doppler frequency, and frame rate.

Purpose of the Study:

• To introduce a spread-spectrum color Doppler imaging method.
• To eliminate the trade-off between beam quality, maximum unaliased Doppler frequency, and frame rate.
• To enable high-resolution ultrasound imaging with high frame rates and improved Doppler measurements.

Main Methods:

• Utilizes a spread-spectrum technique with a random sequence of transmit angles instead of linear sweeps.
• Randomizes clutter signal phase, spreading clutter power in the Doppler spectrum while preserving in-focus signal spectrum.
• Employs randomly tilted low-resolution frames as the Doppler ensemble for improved beam formation and Doppler sampling.

Main Results:

• Achieves high-resolution images without compounding, overcoming limitations of conventional plane-wave imaging.
• Demonstrates more accurate measurement of parabolic flow profiles in phantom studies.
• Outperforms conventional plane-wave Doppler in contrast resolution and high flow velocity estimation.

Conclusions:

• The spread-spectrum method provides high-resolution ultrasound imaging without compounding, enhancing Doppler capabilities.
• This technique successfully overcomes the limitations of conventional plane-wave compounding for Doppler imaging.
• The spread-spectrum approach is highly valuable for Doppler applications requiring high velocities at high frame rates.