MRE Imaging for Elasticity and Viscosity of Biological Tissues

Abstract

This paper discusses an MR Elastography (MRE) method for noninvasive measurement of elasticity and viscosity of biological tissues. In this imaging method, bipolar gradients put into any pulse sequence for MRI. The phase contrast of acquired image is changed by the number of bipolar gradients and their amplitude. From acquired signal (gradient echo and/or spin echo), changing of the phase of magnetized spin is calculated, and analyzed frequency response of applied mechanical vibration from the outside of the biological tissue. The frequency and amplitude of applied mechanical vibration should be changed by elasticity and viscosity of the tissues. The frequency of applied mechanical vibration is from around 100 Hz by mechanical vibrator to high around 1MHz by ultrasound device. In the post processing, elasticity and viscosity is calculated and the phase shift of magnetized spin is analyzed in two or three dimensions. An image is reconstructed as MRE image which is extracted and enhanced elasticity and viscosity of biological tissues.