Isolation of microbubbles beyond Sparrow's resolution limit in super-resolution ultrasonography using phase patterned...

Area of Science:

• Medical Imaging
• Acoustic Physics
• Biomedical Engineering

Background:

• Super-resolution ultrasonography (SR-US) offers detailed microvasculature imaging for enhanced diagnostics.
• Current SR-US methods require low concentrations of microbubbles (MBs), leading to lengthy data acquisition times.
• Efficiently imaging at higher MB concentrations is crucial for advancing SR-US speed and diagnostic capabilities.

Purpose of the Study:

• To develop and validate a novel method for isolating and detecting individual microbubbles (MBs) at high concentrations.
• To enable high-speed super-resolution ultrasonography (SR-US) by reducing acoustic data acquisition times.
• To improve the efficiency and accuracy of MB detection in SR-US imaging.

Main Methods:

• Utilized phase patterned waves (PPWs) to precisely control the sound pressure and isolate individual MBs by adjusting their point spread function (PSF) intensities.
• Exploited destructive interference in PPWs to achieve axial distance discrimination of MBs, complementing lateral discrimination.
• Combined lateral and axial position estimations to determine precise 2D coordinates of MBs, even when closely spaced.

Main Results:

• Achieved accurate MB position estimation within 25% of the wavelength, surpassing Sparrow's resolution limit for closely located MBs.
• Improved positional accuracy to an average of 15% of the wavelength using an overlapped PSF model, irrespective of MB proximity or number.
• Demonstrated the capability to isolate and detect individual MBs effectively even at high concentrations.

Conclusions:

• The developed PPW-based method successfully isolates individual MBs at high concentrations, overcoming limitations of conventional ultrasound plane waves.
• This technique significantly reduces acoustic data acquisition time, paving the way for high-speed SR-US.
• The enhanced MB detection accuracy holds promise for improved diagnostic precision and clinical applications of SR-US.