Regional-Lag Signed Delay Multiply and Sum Beamforming in Ultrafast Ultrasound Imaging

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Signal Processing

Background:

• Ultrafast ultrasound imaging offers high frame rates but suffers from poor image quality due to unfocused beams.
• Traditional delay multiply and sum (DMAS) beamforming improves contrast but causes oversuppression, leading to low-quality speckle images.
• Signed DMAS (sDMAS) balances speckle preservation and resolution but has limitations with hyperechoic scatterers.

Purpose of the Study:

• To introduce a novel regional-lag signed delay multiply and sum (rsDMAS) beamformer to overcome the limitations of existing methods.
• To enhance contrast and speckle preservation in ultrafast ultrasound imaging while maintaining lateral resolution.

Main Methods:

• The proposed rsDMAS beamformer utilizes a generalized coherence factor (GCF) for region discrimination to limit spatial coherence estimation lag.
• Employs subaperture coherence smoothing for reduced computational complexity and improved speckle texture.
• Incorporates normalization and sign correction for optimized beamforming output.

Main Results:

• rsDMAS demonstrated significant improvements in contrast ratio (CR) by 9%, contrast-to-noise ratio (CNR) by 41%, and speckle signal-to-noise ratio (sSNR) by 41% compared to DMAS in simulations.
• Achieved a generalized contrast-to-noise ratio (gCNR) improvement of 0.0004 over DMAS.
• Resolution experiments showed a minimal loss of 0.07 mm in full width at half maximum (FWHM) with comparable separability of point scatterers.

Conclusions:

• The rsDMAS beamformer effectively enhances contrast performance in ultrafast ultrasound imaging.
• It achieves superior speckle preservation and contrast compared to DMAS with only a minor trade-off in lateral resolution.
• The proposed method offers a promising solution for improving diagnostic quality in ultrafast ultrasound applications.