Viscoelastic properties of gel material and soft tissue measured by MRE (Magnetic Resonance Elastography) using micro MRE

Abstract

Magnetic resonance elastography (MRE) was developed for detecting the region and the stage of disease by changing in the hardness of human tissue or organ. The MRE technology requires an external excitation system for generating transverse waves to the subject in the gantry of MRI. Stiffness of the organ is quantitatively calculated from the wave patterns through a mathematical model. Techniques to measure viscoelastic property of soft materials have been developed. For example, rheometer and ultrasound elastography has been generally used for gel materials and soft tissues. For example, rheometer and ultrasound elastography has been generally used for gel materials and soft tissues. Magnetic resonance elastography have an important role to measure a distribution of quantitative viscoelastic property under a keeping shape of soft material objects and an influence of frequency. In this study, we focused the viscoelastic property of gel material and soft tissue measured by the MRE based on the micro MRI (0.3 T) designed from a high-power vibration generator and a bartype vibration transmitter. The MRE represent the viscoelastic property at a complex modulus G*=G’+iG”. The storage shear modulus G’ and the loss shear modulus G” shows elasticity and viscosity, respectively. Specimens made by gelatin gel and bovine liver and muscle. We report about influence of excitation frequency that is used 62.5 to 500 Hz and specimen boundary condition that fix each plane of the specimen. The G’ of gelatin gel increase with the frequency. We will discuss about the boundary condition of the specimen and the soft tissue.