Electromechanical mapping with MRI tagging and epicardial sock electrodes

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Cardiac Electrophysiology

Background:

• Precise measurement of local 3D myocardial motion is achievable noninvasively using magnetic resonance imaging (MRI) tagging.
• Strain imaging derived from motion estimates visualizes local myocardial contraction and relaxation sequences.
• Abnormalities due to asynchronous electrical activation or ischemia can be visualized using these strain images.

Purpose of the Study:

• To investigate the relationship between electrical activity and mechanical function on a local level in the in vivo heart.
• To utilize near simultaneous mapping of electrical depolarization with MRI tagging.
• To assist in the construction of a whole-heart electromechanical model.

Main Methods:

• Noninvasive measurement of local 3D myocardial motion using MRI tagging.
• Formation of strain images from motion estimates to represent myocardial deformation.
• Near simultaneous mapping of electrical depolarization using a sock electrode array.
• Acquisition of registered fiber angle maps using diffusion MRI.

Main Results:

• Strain images clearly show the sequence of mechanical events during cardiac activation and relaxation.
• The study enables investigation of the electromechanical relationship in the in vivo heart.
• Fiber angle maps can be obtained to aid in electromechanical modeling.

Conclusions:

• MRI tagging provides precise myocardial motion measurement and visualization of cardiac mechanics.
• Combining electrical and mechanical mapping allows for local-level investigation of electromechanical coupling.
• The developed methods support the creation of comprehensive electromechanical models of the heart.