The Study of Mechanical Properties and Relaxation Time of Agar Hydrogel for Tissue Mimicking Phantom Material in Magnetic Resonance Imaging

Abstract

Agar hydrogel is used for tissue mimicking phantom in magnetic resonance imaging studies. The spin-lattice relaxation time, T1 as an important parameter in Magnetic Resonance Imaging measurement was observed. The T1-value represents how fast the net spin magnetization vector recovers to its equilibrium after generation of magnetic field. To explore mechanical properties of agar, shear modulus was examined using a dynamic mechanical analyser. The relation between mechanical properties and spin-lattice relaxation time of agar hydrogel is discussed.

Signal-to-noise ratio uniformity and stability of agar gel phantom with iron (III) oxide as relaxation modifier

“…This trend can be observed in all agar gel phantoms with the addition of Fe 2 O 3 as a relaxation modifier. Pure agar hydrogel and agarose gel phantoms in other studies have exhibited a similar trend of SNR signal reduction as TE increased with T2 values of 116.71 ms and 150.00 ms, respectively [5,19]. The T2 values of the agar gel phantoms in this study are still in the range of T2 for human tissues (40-150 ms) [1].…”

“…This creates a high barrier for hydrogen spins to move resulting in a shorter T1. It has also been reported that high gel phantom concentrations resulted in low T2 due to its low water content after evaporation, indicating less dipole-dipole interaction for the mechanism of T2 relaxation [4,19]. In this study, the concentration of agar gel phantoms was fixed at 0.03 gml −1 ; hence, any change in T1 and T2 relaxations within and between TP1 and TP2 was not attributed to the concentration of the gelling agent.…”

“…The argument of this sort should also apply to SNR o and SNR i . Nevertheless, in previous studies, the addition of low concentration of paramagnetic ions have been found to show a large reduction in both SNR o and T1 values of the phantoms [1,13,[19][20][21].…”

“…Several studies have demonstrated that the concentration of gelling agent would affect the T1 and T2 of the gel phantoms [19][20][21][22][23]. In those studies, it was found that by increasing the concentration of gelling agents reduced the T1 of the gel phantoms.…”