Dual-modality flow phantom for ultrasound and optical flow measurements

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Fluid Dynamics

Background:

• Ultrasound flow phantoms are crucial for testing and calibration.
• Independent validation using gold-standard techniques like particle image velocimetry (PIV) is needed.
• Existing phantoms may not support simultaneous multi-modal measurements.

Purpose of the Study:

• To design and present a novel dual-modality flow phantom for simultaneous ultrasound and PIV measurements.
• To validate the performance of ultrasound flow mapping tools against PIV.
• To characterize the optical and acoustic properties of a new tissue-mimicking hydrogel.

Main Methods:

• Developed a novel hydrogel using propylene glycol and poly(vinyl) alcohol cryogel for optical transparency and ultrasound compatibility.
• Fabricated a bimodal flow phantom with a spiral lumen.
• Performed simultaneous flow measurements using PIV and ultrasound color flow imaging (CFI) at a constant flow rate.

Main Results:

• The hydrogel exhibited suitable optical attenuation, refractive index, acoustic attenuation, and speed of sound for dual-modality measurements.
• Comparison of velocity fields and profiles showed CFI overestimated flow speed compared to PIV.
• Percentage differences between PIV and ultrasound measurements ranged from 6% to 14% depending on the angle.

Conclusions:

• The developed dual-modality flow phantom is feasible for simultaneous PIV and ultrasound measurements.
• This phantom enables effective performance validation of ultrasound flow mapping tools.
• The novel hydrogel material is suitable for creating advanced flow phantoms.