MR elastography as a method for the assessment of myocardial stiffness: comparison with an established pressure-volume model in a left ventricular model of the heart.

Magnetic resonance elastography (MRE) measurements of shear stiffness (mu) in a spherical phantom experiencing both static and cyclic pressure variations were compared to those derived from an established pressure-volume (P-V)-based model. A spherical phantom was constructed using a silicone rubber composite of 10 cm inner diameter and 1.3 cm thickness. A gradient echo MRE sequence was used to determine mu within the phantom at static and cyclic pressures ranging from 55 to 90 mmHg. Average values of mu using MRE were obtained within a region of interest and were compared to the P-V-derived estimates. Under both static and cyclic pressure conditions, the P-V- and MRE-based estimates of mu ranged from 98.2 to 155.1 kPa and 96.2 to 150.8 kPa, respectively. Correlation coefficients (R(2)) of 0.98 and 0.97 between the P-V and MRE-based estimates of shear stiffness measurements were obtained. For both static and cyclic pressures, MRE-based measures of mu agree with those derived from a P-V model, suggesting that MRE can be used as a new, noninvasive method of assessing mu in sphere-like fluid-filled organs such as the heart.