Polyvinyl alcohol cryogel: An ideal phantom material for MR studies of arterial flow and elasticity

Abstract

The authors present a unique application of polyvinyl alcohol (PVA) cryogel as an anthropomorphic, elastic, vascular phantom material that can be used in MR imaging. The composition consists of two nontoxic ingredients: water and PVA. The biomechanical and MR properties can be adjusted to be similar to those of excised porcine aortas by varying the number of freeze-thaw cycles to which the PVA solution is exposed. The authors present the T1, T2, shrinkage, and tensile properties of PVA cryogel tubes as a function of freeze-thaw cycles. MR images of a dual elastic aortic phantom undergoing pulsatile motion are shown.

Development of a Vessel-Mimicking Material for use in Anatomically Realistic Doppler Flow Phantoms

“…This may suggest that the PVA-C material was approaching saturation point of the cryogel in terms of intermolecular cross-linking. This effect has been observed elsewhere (Chu and Rutt, 1997) and places an upper limit on Young's elastic moduli available for a given concentration of cryogel. The Young's elastic modulus values, which ranged from 19 to 165 kPa in the current study, are similar to those obtained by Duboeuf et al (2007) for 10 % PVA-C concentration.…”

“…Indeed, bacterial growth appeared on a number of PVA-C samples which did not contain any anti-bacterial agent after several days. Chu and Rutt (1997) used an anti-bacterial agent in their PVA-C samples and indicated that the agent changed the MR relaxometry properties of their samples; however, they did not quantify this change. The use of Benzalknonium Chloride (BC) in the current study stemmed from its use in a previous study, where it was observed to increase the lifetime of a TMM (Teirlinck et al 1998).…”

“…There is growing interest in the use of Polyvinyl Alcohol Cryogel (PVA-C) to mimic a range of tissue properties for applications in magnetic resonance imaging (MRI) (Chu and Rutt 1997) and ultrasound (Cournane et al 2010;Dineley et al, 2006;Surry et al 2004)),…”

“…It is therefore advantageous to add an anti-bacterial agent to the PVA-C which can help to increase the lifetime of the sample. Chu and Rutt (1997) stated that the addition of an anti-bacterial agent changes the VMM properties slightly but no data was presented to support this statement. The acoustic and mechanical properties of a range of PVA-C samples reported in the literature for use as a VMM are presented in Table 1, together with typical values for human soft tissue and aorta.…”

“…The large variation in results across these publications reflects the different manufacturing recipe used in each study, and to date no one study has systematically investigated the effect of varying each of these parameters on the resulting properties, with a view to optimizing the manufacturing steps required to produce an optimal set of acoustic and mechanical properties for use as a VMM. (Duck 1990), † (Greenleaf et al, 1974) , ‡ (Kawasaki et al 1987) , § (Surry et al 2004), || (Duboeuf et al 2007), ** (Dineley et al 2006), † † (Chu and Rutt 1997), § § Cournane et al 2010 The current study aimed to investigate the effect of systematically varying the number of freeze/thaw cycles on a range of samples containing PVA-C alone, PVA-C containing an anti-bacterial agent, and PVA-C which contained silicon carbide particles with/without the anti-bacterial agent. The viscoelastic behavior of the optimum preparation thus determined was then investigated.…”