Superharmonic and Microultrasound Imaging With Plane Wave Beamforming Techniques

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Superharmonic contrast imaging (SpHI) is crucial for high-contrast visualization of vasculature by suppressing tissue clutter.
• Microbubble (MB) contrast agents exhibit broadband nonlinear responses beneficial for SpHI.
• Existing methods may be limited in frame rate and resolution for detailed vascular imaging.

Purpose of the Study:

• To implement ultrafast plane wave imaging for SpHI to increase acquisition frame rates.
• To develop high-resolution microultrasound B-mode imaging (HFPW B-mode) for tissue structure visualization.
• To demonstrate coherent compounding in both SpHI and HFPW B-mode for enhanced image quality in vitro and in vivo.

Main Methods:

• Integration of a 21-MHz microultrasound array with a 2-MHz array for a dual-frequency (DF) probe.
• Application of ultrafast plane wave imaging for both SpHI and HFPW B-mode.
• In vitro and in vivo experiments utilizing coherent compounding with varying angles.

Main Results:

• Achieved high frame rates: 4.5 kHz (HFPW B-mode) and 3.5 kHz (SpHI) with single angle, and 187 Hz (HFPW B-mode) and 396 Hz (SpHI) with compounding.
• Demonstrated significant clutter suppression in SpHI images both pre- and post-MB injection.
• Reported improved contrast-to-tissue ratio (CTR) of 2.5-2.6 dB with nine-angle compounding in SpHI, revealing nonviable tissue and finer vasculature (<0.1 mm).

Conclusions:

• Ultrafast plane wave imaging combined with a dual-frequency probe effectively enhances SpHI performance.
• Coherent compounding significantly improves contrast enhancement and the detection of small vessels in SpHI.
• This advanced imaging approach offers superior visualization of tumor vasculature and tissue characteristics.