Ultrafast Synthetic Transmit Aperture Imaging Using Hadamard-Encoded Virtual Sources With Overlapping Sub-Apertures

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Signal Processing

Background:

• Ultrafast ultrasound imaging presents a trade-off between image quality (SNR, resolution) and frame rate.
• Existing methods like multiplane wave imaging and synthetic aperture imaging aim to overcome these limitations.

Purpose of the Study:

• To introduce an Ultrafast Synthetic Transmit Aperture (USTA) imaging technique.
• To enhance image signal-to-noise ratio (SNR) and resolution in ultrafast ultrasound without compromising frame rate.

Main Methods:

• USTA employs Hadamard-encoded virtual sources derived from overlapping sub-apertures.
• Virtual sources are encoded using a Hadamard matrix with short transmission intervals.
• The method involves creating virtual sources, Hadamard encoding, and utilizing overlapping sub-apertures.

Main Results:

• USTA demonstrated improved image SNR, lateral resolution (+33% in phantom imaging), and contrast ratio (+3.8 dB in vivo kidney imaging) compared to standard methods.
• Experimental validation was performed using a point target, B-mode phantom, and in vivo human kidney micro-vessel imaging.
• Adjustable parameters (f-number, number of virtual sources, sub-aperture elements) allow flexible optimization.

Conclusions:

• USTA effectively addresses the SNR-resolution-frame rate trade-off in ultrafast ultrasound imaging.
• The technique offers a flexible approach for optimizing image quality across various ultrasound applications.
• USTA shows significant potential for advancing diagnostic ultrasound capabilities.