Null subtraction imaging combined with modified delay multiply-and-sum beamforming for coherent plane-wave...

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Signal Processing

Background:

• Coherent plane-wave compounding in ultrafast ultrasound imaging offers efficiency but compromises image quality due to unfocused waves.
• Delay multiply-and-sum (DMAS) beamformers improve image quality but can lead to over-suppression, negatively impacting speckle quality.
• Existing DMAS methods present trade-offs between image contrast, resolution, and speckle preservation.

Purpose of the Study:

• To develop a novel beamformer that integrates null subtraction imaging (NSI) with delay multiply-and-sum (DMAS).
• To overcome the limitations of current DMAS methods by improving speckle quality without sacrificing resolution and contrast.
• To evaluate the performance of the proposed combined NSI-DMAS beamformer.

Main Methods:

• Investigated a new beamformer combining NSI and DMAS.
• Employed NSI and delay and sum (DAS) at receive, performing multiply-and-sum across the transmitting dimension.
• Evaluated the method using simulation, phantom, and in vivo ultrasound datasets.

Main Results:

• The proposed method demonstrated improved contrast ratio (+10.02%), speckle signal-to-noise ratio (+45.19%), and generalized contrast-to-noise ratio (+12.37%) compared to NSI.
• Achieved an improvement in full width at half maximum (resolution) of up to 0.24 mm.
• Successfully balanced speckle quality (akin to DAS) with high resolution (akin to NSI).

Conclusions:

• The combined NSI-DMAS beamformer effectively enhances ultrasound image resolution and contrast.
• The proposed method alleviates the over-suppression issue common in DMAS, preserving speckle quality.
• This technique offers a superior alternative for ultrafast ultrasound imaging, improving diagnostic accuracy.