Single-element focused ultrasound transducer method for harmonic motion imaging

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Acoustic Physics

Background:

• Previous harmonic motion imaging (HMI) used two focused ultrasound transducer elements.
• Simultaneous monitoring and generation of ultrasound therapy requires precise control.

Purpose of the Study:

• To develop and validate a novel HMI technique using a single focused ultrasound element.
• To image tissue displacement induced by harmonic radiation force.
• To enable real-time, stiffness-dependent measurements and HIFU monitoring.

Main Methods:

• A single 4.68 MHz focused ultrasound transducer generated radiation force with a 50 Hz amplitude-modulated wave.
• A 7.5 MHz pulse-echo transducer acquired radiofrequency echoes.
• 1D cross-correlation estimated axial tissue displacement from acquired echoes.

Main Results:

• Wave propagation simulations confirmed a stable focal zone with the amplitude-modulated beam.
• The HMI technique successfully estimated stiffness-dependent displacement amplitudes in phantoms and ex vivo tissues.
• Real-time temperature-dependent measurements allowed monitoring of HIFU sonication.

Conclusions:

• The new single-element HMI technique provides localized, stiffness-dependent measurements.
• This method offers real-time and cost-effective monitoring of high-intensity focused ultrasound (HIFU).
• The technique has potential applications in ultrasound therapy and diagnostics.