Eigenspace generalized sidelobe canceller combined with SNR dependent coherence factor for plane wave imaging.

Area of Science:

• Ultrasound Imaging
• Medical Physics
• Signal Processing

Background:

• Coherent plane wave compounding (CPWC) imaging quality is often limited by low signal-to-noise ratio (SNR).
• Conventional coherence factor (CF) methods like generalized CF and subarray CF struggle in low SNR environments.
• Eigenspace generalized sidelobe canceller (EGSC) beamformers offer improvements but can degrade in low SNR CPWC.

Purpose of the Study:

• To introduce and evaluate a novel SNR-dependent coherence factor (CF) method for CPWC imaging.
• To overcome the limitations of existing CF methods in low SNR conditions.
• To enhance image quality, specifically spatial resolution and contrast, in CPWC.

Main Methods:

• Utilized Field II simulations and a Verasonics ultrasound system with an L11-4v array for data acquisition.
• Employed a contrast resolution phantom to capture plane wave sequences.
• Evaluated performance using full width at half maximum (FWHM), contrast ratio (CR), CNR, and speckle statistics (SNR, Rayleigh distribution).
• Compared the proposed SNR-dependent CF (denoted as [Formula: see text]) against generalized CF ([Formula: see text]) and subarray CF ([Formula: see text]).

Main Results:

• The proposed [Formula: see text] method demonstrated significant improvements over DAS (Direct Data Acquisition), showing 30.3% and 39.5% enhancement in experimental data.
• It slightly outperformed generalized CF ([Formula: see text]) and subarray CF ([Formula: see text]) in FWHM, CR, CNR, and speckle statistics.
• The method effectively controls SNR levels, mitigating degradation issues common in low SNR scenarios.

Conclusions:

• The proposed SNR-dependent coherence factor ([Formula: see text]) is highly suitable for CPWC imaging.
• It successfully improves spatial resolution and contrast while preserving essential speckle patterns.
• This method offers a robust solution for enhancing ultrasound image quality in challenging low SNR conditions.