Effects of phase aberration correction methods on the minimum variance beamformer

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Signal Processing

Background:

• Minimum variance (MV) beamforming offers enhanced resolution and contrast in ultrasound imaging.
• MV beamformers are sensitive to speed of sound errors and phase aberrations.
• Phase aberration correction (PAC) methods are established for conventional delay-and-sum (DAS) but their benefit for MV beamforming is unclear.

Purpose of the Study:

• To analyze the impact of three PAC algorithms on MV beamformer performance with phase aberrations.
• To evaluate the effectiveness of PAC in mitigating aberration effects on MV beamformed ultrasound images.
• To inform the design of robust MV beamformers using PAC.

Main Methods:

• Tested three PAC algorithms: multi-lag cross-correlation, Rigby's beamsum, and scaled covariance matrix.
• Evaluated PAC methods combined with MV beamforming on simulated and experimental data.
• Introduced controlled phase aberrations using an electronic near-field phase aberrator.

Main Results:

• MV beamformer performance gains over DAS are lost at high aberration strengths (e.g., 600% lateral resolution degradation vs. 22% for DAS).
• PAC methods substantially improve aberrated MV beamformer performance, reducing lateral resolution degradation from 600% to 5%.
• Significant improvements were observed in peak sidelobe level, contrast, and contrast-to-noise ratio with PAC, enabling MV to outperform DAS.

Conclusions:

• PAC methods are crucial for maintaining MV beamformer performance in the presence of significant phase aberrations.
• The integration of PAC with MV beamforming enhances image quality metrics beyond conventional DAS, even in challenging conditions.
• This study provides a foundation for developing robust ultrasound beamformers resilient to acoustic aberrations.