AN IMPROVED TISSUE-MIMICKING POLYACRYLAMIDE HYDROGEL PHANTOM FOR VISUALIZING THERMAL LESIONS …
AN IMPROVED TISSUE-MIMICKING POLYACRYLAMIDE HYDROGEL PHANTOM FOR VISUALIZING THERMAL LESIONS WITH HIGH-INTENSITY FOCUSED ULTRASOUND
Abstract—A recipe was created to improve the tissue-mimicking (TM) bovine serum albumin (BSA) polyacryl-
amide hydrogel (PAG) reported in our previous study (Choi MJ, Guntur SR, Lee KI, Paeng DG, Coleman AJ.
Ultrasound Med Biol 2013; 29:439–448). In that work, the concentration of acrylamide in TM BSA PAG was
increased to make its attenuation coefficient the same as that of a tissue. However, this increase made the PAG
stiffer and less homogeneous. In addition, the increase in acrylamide caused a significant increase in temperature
over the denaturation threshold of BSA during polymerization, which requiredforced cooling so that the PAG did
not become opaque at room temperature after polymerization. To eliminate those shortcomings, we substituted
the increased acrylamide with a viscous polysaccharide liquid (corn syrup). The concentration of corn syrup
was optimized to 20% (w/v, tested in the volume of 50 mL), so that the acoustic properties of the PAG would
be close to those of human liver. The improved TM (iTM) BSA PAG constructed in this study had a speed of sound
of 1588 ± 9 m/s, an attenuation coefficient of 0.51 ± 0.06 dB cm-1 at 1 MHz and a back scattering coefficient of
0.22 ± 0.09 X 10-3 sr-1 cm-1 MHz-1. The density and acoustic impedance were 1057 kg/m3 and 1.68 MRayl,
respectively, and the non-linear parameter (B/A) was 5.9 ± 0.3. The thermal, optical and mechanical properties
were almost the same as those of the BSA PAG (Lafon et al.2005). Experimental verification indicated that the
thermal lesions visualized in the proposed iTM BSA PAG by high-intensity focused ultrasound were highly repro-
ducible. In conclusion, iTM BSA PAG was proven to eliminate TM BSA PAG shortcomings effectively and is ex-
pected to be a promising test phantom for clinical high-intensity focused ultrasound device.
Key Words: Tissue mimicking, Phantom, Polyacrylamide hydrogel, Bovine serum albumin, High intensity focused
ultrasound, Polysaccharide, Corn syrup, Visualization, Thermal lesion.
Link : https://www.sciencedirect.com/science/article/pii/S0301562914004207
