Design and characterisation of a wall motion phantom.

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Medical Imaging Physics

Background:

• Arterial wall motion is crucial for cardiovascular health, but its assessment is challenged by accuracy and variability issues.
• Existing ultrasound techniques for measuring wall motion require development of suitable test tools for reliable diagnostic information.

Purpose of the Study:

• To describe a novel vessel wall phantom for use in ultrasound studies of arterial wall motion.
• To evaluate the properties and performance of the developed phantom in simulating physiological conditions.

Main Methods:

• A vessel wall phantom was fabricated using polyvinyl alcohol (PVA) subjected to a freeze-thaw process, creating a cryogel (PVA-C).
• The elastic modulus, acoustic velocity, and attenuation coefficient of the PVA-C were characterized across varying freeze-thaw cycles.
• Pulsatile flow was introduced to induce wall motion, with a downstream flow resistor used to manage waveform distortions.

Main Results:

• The PVA-C phantom's properties (elastic modulus, acoustic velocity, attenuation) varied with the number of freeze-thaw cycles, ranging from 57 kPa to 330 kPa.
• Pulsatile flow successfully induced wall motion, and a flow resistor mitigated gross waveform distortions.
• A residual 20 Hz oscillation, deemed unphysiologic, was observed and attributed to PVA-C vessel vibration.

Conclusions:

• The developed PVA-C phantom offers a valuable tool for ultrasound studies of arterial wall motion.
• The phantom's tunable properties and ability to simulate pulsatile flow provide a basis for improving the accuracy of cardiovascular diagnostics.
• Further refinement is needed to eliminate residual oscillations for more accurate physiological simulation.