Considerations for Gradient Echo Echo Planar Imaging of Skeletal Muscle

Area of Science:

• Physiology
• Medical Imaging

Background:

• Adequate muscle blood circulation is vital for health.
• Magnetic resonance imaging (MRI) is increasingly used to study muscle physiology.
• Gradient echo (GRE) echo planar imaging (EPI) is a key MRI technique for this purpose.

Purpose of the Study:

• To comprehensively review the muscle GRE EPI literature.
• To elucidate GRE EPI signal characteristics by comparing with other modalities.
• To describe physiological factors influencing GRE EPI signals during and after exercise.

Main Methods:

• Review of existing muscle GRE EPI literature.
• Emphasis on studies comparing GRE EPI with other imaging modalities.
• Analysis of systemic and muscle physiological factors affecting the GRE EPI signal.

Main Results:

• GRE EPI is sensitive to muscle blood flow and oxygenation changes.
• Adjusting echo time (TE) allows for blood volume (BV) or blood oxygenation level dependent (BOLD) imaging.
• Identified key physiological factors: temperature, blood flow, oxygen saturation, myoglobin, and posture.

Conclusions:

• GRE EPI is a valuable tool for assessing muscle physiological changes.
• Understanding influencing factors is crucial for accurate interpretation of muscle MRI data.
• Predictive models of signal dynamics during exercise can be developed based on published literature.