Polyvinyl alcohol cryogel elastic artery phantoms for ultrasonic flow and elasticity measurements

The biophysical properties of arteries and blood flow have played important roles in the development of cardiovascular diseases. Increased arterial stiffness causes reduced vasomotion capability of an artery and influences the local hemodynamics. Designing and fabricating elastic vessel phantoms for use in physiological flow condition can add valuable alternatives to intravital and computational studies. This paper used polyvinyl alcohol (PVA) cryogel to fabricate elastic artery phantoms and performed detailed acoustic and mechanical characterization. A PVA solution in water was prepared, injected into a custom-designed mould, and subjected to a number of freeze-thaw (f-t) cycles. The obtained vessel phantoms were empty cylinders with 6 mm inner diameter, 2mm wall thickness, and 160 mm length. Young's modulus was measured, and a linear increase was observed from one cycle to eight cycles. The sound speed and the attenuation coefficient of the cylindrical samples were determined using the pulse-echo substitution method. Six different transducers were used in this study, operating at six different frequencies. Sound speed is dependent on transmit frequency, but not number of f-t cycle. At fixed transmit frequency, an increase of sound speed can be observed against the number of f-t cycles. Sound attenuation coefficient are dependent on both the transmit frequency and the number of f-t cycles. The PVA-C vessel phantom can be used to construct physiological flow circulation and perform the hemodynamics parameter measurements using ultrasonic or MRI techniques.