Three-dimensional static displacement, stimulated echo NMR elasticity imaging

This article presents a method for measuring three-dimensional mechanical d isplacement and strain fields using stimulated echo MRI. Additional gradien t pulses encode internal displacements in response to an externally applied deformation. By limiting the mechanical transition to the stimulated echo mixing time, a more accurate static displacement measurement is obtained. A three-dimensional elasticity reconstruction within a region of interest ha ving a uniform shear modulus along its boundary is performed by numerically solving discretized elasticity equilibrium equations. Data acquisition, st rain measurements and reconstruction were performed using a silicone gel ph antom containing an inclusion of known elastic properties. A comparison bet ween two-dimensional and three-dimensional reconstructions from simulated a nd experimental displacement data shows higher accuracy from the three-dime nsional reconstruction. The long-term objective of this work is to provide a method for remotely palpating and elastically quantitating manually inacc essible tissues.