What is the clinical evidence from this study?

Study design: Observational. Population: Healthy volunteers (n=6). Intervention: Magnetic resonance elastography (MRE). Primary outcome: Changes in myocardial elasticity over the cardiac cycle.

What does this research mean for the field?

Magnetic resonance elastography demonstrates that myocardial wave amplitudes are up to 2.45 times higher during diastole than systole, indicating a 37.7-fold maximum change in myocardial wall stiffness over the cardiac cycle. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

December 18, 2008Open Access

MR elastography of the human heart: Noninvasive assessment of myocardial elasticity changes by shear wave amplitude variations

Key Result

Magnetic resonance elastography demonstrated that myocardial wave amplitudes were up to 2.45 higher during diastole than systole, indicating a 37.7-fold maximum change in wall stiffness.

Study Design

Type

Observational (n=6)

Structured PICO

Does magnetic resonance elastography allow noninvasive assessment of myocardial elasticity changes over the cardiac cycle in healthy volunteers?

Population

6 healthy volunteers

Intervention

Magnetic resonance elastography (MRE) technique using low-frequency shear vibrations of 24.3 Hz induced via the anterior chest wall and an ECG-triggered, steady-state MRE sequence

Outcome

Changes in myocardial elasticity over the cardiac cycle measured by shear wave amplitude variationssurrogate

MR elastography is a feasible noninvasive technique to measure significant dynamic changes in myocardial wall stiffness throughout the cardiac cycle.

Abstract

Many cardiovascular diseases and disorders are associated with hemodynamic dysfunction. The heart's ability to contract and pump blood through the vascular system primarily depends on the elasticity of the myocardium. This article introduces a magnetic resonance elastography (MRE) technique that allows noninvasive and time-resolved measurement of changes in myocardial elasticity over the cardiac cycle. To this end, low-frequency shear vibrations of 24.3 Hz were induced in the human heart via the anterior chest wall. An electrocardiograph (ECG)-triggered, steady-state MRE sequence was used to capture shear oscillations with a frame rate of eight images per vibration cycle. The time evolution of 2D-shear wave fields was observed in two imaging planes through the short axis of the heart in six healthy volunteers. Correlation analysis revealed that wave amplitudes were modulated in synchrony to the heartbeat with up to 2.45 +/- 0.18 higher amplitudes during diastole than during systole (interindividual mean +/- SD). The reduction of wave amplitudes started at 75 +/- 9 ms prior to changes in left ventricular diameter occurring at the beginning of systole. Analysis of this wave amplitude alteration using a linear elastic constitutive model revealed a maximum change in the myocardial wall stiffness of a factor of 37.7 +/- 10.6 during the cardiac cycle.