Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

Abstract

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s(-1), and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz)(-1). T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.

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

“…This step was counted as the first freeze-thaw cycle. From previous studies it was decided that 1 -6 freeze-thaw cycles were sufficient to obtain the desired range of acoustic and mechanical properties similar to in vivo arteries (Surry et al 2004;Dineley et al 2006). The first batch (Batch-1) was sub-divided into six groups depending on the number of freeze-thaw cycles used (1 -6), while Batch-2 and Batch-3 were divided into three groups corresponding to 2, 4 and 6 freeze-thaw cycles.…”

“…However, work in this area is limited (Poepping et al 2004;Surry et al 2004;Dineley et al 2006). Furthermore, although the International Electrotechnical Commission (IEC) publish specifications for the required properties of TMMs (IEC 2001), there are no separate specifications for the properties of VMMs.…”

“…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)),…”

“…From an ultrasound perspective, a particular problem with the use of PVA-C lies in its low acoustic attenuation coefficient, although this shortcoming has been resolved through the addition of enamel paint or particles such as silicon carbide to the mix (Surry et al 2004;Dineley et al 2006). Another feature of PVA-C is that it is hydrophilic and if exposed to air there is a possibility that bacterial growth can occur.…”

“…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.…”