Study of myocardial fiber pathway using magnetic resonance diffusion tensor imaging

Area of Science:

• Cardiovascular Imaging
• Cardiac Mechanics
• Biomedical Engineering

Background:

• Understanding myocardial fiber architecture is crucial for cardiac mechanics.
• Previous methods have limitations in detailed fiber pathway analysis.

Purpose of the Study:

• To investigate myocardial fiber pathway distribution using diffusion tensor imaging (DTI).
• To provide supplemental information on myocardial fiber architecture and cardiac mechanics.
• To correlate fiber pathway length and helix angle.

Main Methods:

• Diffusion tensor imaging (DTI) with 15 directions was performed on 6 fixed canine hearts.
• Diffusion tensor fiber tracking was used to compute myocardial fiber pathways and helix angles.
• Quantitative analysis of fiber pathway length and number as a function of helix angle (9-degree steps).

Main Results:

• Long fiber pathways with small helix angles (-20 to 20 degrees) were identified.
• These pathways are predominantly in the middle myocardium and run circumferentially.
• Fiber pathways in the middle and upper left ventricle (LV) were longer than those near the apex.

Conclusions:

• Myocardial fiber pathway measurements by DTI may reflect spatial connectivity.
• The dominance of long, circumferential fiber pathways likely explains the left ventricular contraction pattern.
• This provides insights into the electromechanical activation pathways in the myocardium.