Measurement of acoustic streaming using magnetic resonance

Area of Science:

• Biomedical Engineering
• Acoustics
• Medical Imaging

Background:

• Acoustic streaming, fluid motion induced by sound waves, is relevant to diagnostic ultrasound.
• Understanding acoustic streaming is crucial for optimizing ultrasound applications and interpreting imaging results.

Purpose of the Study:

• To investigate acoustic streaming in water using magnetic resonance imaging (MRI) under conditions relevant to diagnostic ultrasound.
• To quantify streaming velocities and assess the prevalence of acoustic streaming in diagnostic ultrasound scenarios.

Main Methods:

• Utilized phase-detection MRI to image and quantify acoustic streaming.
• Employed a pulsed, weakly-focused 3.5 MHz transducer to generate acoustic streaming in water.
• Measured streaming in an enclosed tube and within open meshes of varying pore sizes.

Main Results:

• Successfully measured acoustic streaming velocities as low as 0.1 mm/s with acoustic power below 1 mW.
• Quantified flow velocities in meshes, reaching 0.9 mm/s at 95 mW in a 3.0 mm pore mesh.
• Demonstrated that acoustic streaming is a widespread phenomenon in diagnostic ultrasound.

Conclusions:

• Magnetic resonance imaging is a sensitive tool for measuring acoustic streaming.
• Acoustic streaming is more prevalent in diagnostic ultrasound than previously thought.
• The combination of MRI and ultrasound shows potential for differentiating and characterizing cystic lesions in vivo.