Development of a Method for Tissue Elasticity Imaging Using Tagged Magnetic Resonance Imaging

TL;DR

This study presents a novel MRI-based method for tissue elasticity imaging that combines a cyclic pressure device, HARP, and FEM to quantify tissue stiffness with good reproducibility and agreement with traditional testing.

Contribution

We developed an integrated MRI technique using a cyclic pressure device, HARP, and FEM for accurate tissue elasticity imaging and stiffness quantification.

Findings

Reproducible pressure generation with <5% variation.

Young's moduli from MRI methods correlated well with material testing.

Method successfully distinguished different phantom stiffness levels.

Abstract

The purpose of this study was to develop a method for tissue elasticity imaging using tagged magnetic resonance imaging (MRI). First, we developed a cyclic pressure device that used air to remotely transmit the power to generate cyclic deformation in an object. The pressure induced by the cyclic pressure device was measured by MRI-compatible force sensors. Second, we developed a software to calculate Young's modulus from tagged MRI data using the harmonic phase (HARP) method and the finite element method (FEM). We also developed a software to extract tag-cross points from tagged MRI data. Finally, we evaluated the usefulness of our method using three homogeneous silicone gel phantoms with different degrees of stiffness in comparison with Young's moduli measured by a material testing machine. The coefficient of variation of the pressure data measured by MRI-compatible force sensors was within 5 %, indicating that the reproducibility of the pressure generated by our cyclic pressure device was good. The Young's moduli obtained by the material testing machine, the HARP method, and the FEM increased with increasing stiffness of the phantoms. There were relatively good agreements among the three methods. These results suggest that our method is useful for tissue elasticity imaging and for quantifying the stiffness of tissues.