HOMOGENEITY AND STABILITY OF POLY (VINYL ALCOHOL) SLIME PHANTOM WITH DIFFERENT BORAX CONCENTRATION

Abstract

Many works have been carried out by researchers to produce phantoms that can replace agar as potential MRI phantom but can be fabricated from cheap and available materials. One potential material is the slime. The possibility to use this material as MRI phantom lies on the following characteristics; soft, viscoelastic, cross-linked physically and chemically able to retain a large quantity of water and possess structural integrity during deformation. However, the information on the homogeneity and stability of the slime under MRI environment is still lacking. This study investigated the homogeneity and stability of poly(vinyl alcohol) (PVA) slime phantom and determine its suitability and potential for MRI phantom. Four sets of slime phantoms with different borax concentration, r = 0.0075 g/ml, 0.0125 g/ml, 0.0175 g/ml and 0.0225 g/ml were prepared by mixing borax solution (borax powder mixed with distilled water) with PVA glue. The T1 and T2 weighted images of the phantoms were acquired using a 3-T MRI system via a turbo spin echo pulse (TSE) sequence for homogeneity investigation. The scans were carried out at four time points (TP) to investigate the stability of the phantoms. The T1 curves showed that SNR increased exponentially as TR was increased (TE fixed) while the T2 curves demonstrated an exponential decrease of SNR as TE was increased (TR fixed). The SNR values measured from selected regions of interest (ROIs) within each phantom were homogeneous but decreased markedly over time. In contrast, the T1 and T2 values were found to be stable over time and in good agreement with the average values of human tissues. The results are promising at least in the context of phantom homogeneity and stability. Further studies are necessary in order to obtain suitable slime phantoms for MRI in actual scale which homogeneity and stability would withstand a longer period of time.