Improved estimation and visualization of two-dimensional myocardial strain rate using MR velocity mapping

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Medical Physics

Background:

• Accurate assessment of regional myocardial strain rate is crucial for diagnosing and managing heart disease.
• Traditional methods for strain rate estimation can be susceptible to noise and external velocity influences, limiting their reliability.

Purpose of the Study:

• To develop and validate a novel method for estimating regional myocardial strain rate with enhanced robustness to noise and off-region velocities.
• To visualize the spatial variation of the myocardial strain rate tensor field for improved understanding of cardiac mechanics.

Main Methods:

• Utilized two-dimensional phase contrast velocity mapping to acquire myocardial velocity data.
• Employed normalized convolution for robust estimation of velocity gradients and the 2D strain rate tensor.
• Visualized the strain rate tensor field using glyph representation and validated with a numerical phantom.

Main Results:

• Normalized convolution demonstrated excellent agreement with the analytic solution in phantom studies, outperforming traditional methods sensitive to noise.
• Normal myocardium exhibited a homogeneous strain rate distribution, contrasting with heterogeneous patterns observed in patient data with myocardial infarction.

Conclusions:

• The proposed quantification and visualization technique provides an objective measure of regional myocardial contraction and relaxation.
• This approach holds potential value for the clinical assessment of myocardial function and heart disease evaluation.