T2 mapping of muscle activity using ultrafast imaging

Area of Science:

• Sports Medicine
• Biomedical Engineering
• Radiology

Background:

• Assessing exercise-induced muscle activity is crucial in sports medicine.
• Traditional muscle functional MRI (mfMRI) using spin-echo sequences is time-consuming.
• Transverse relaxation time (T(2)) mapping is a proposed method for muscle activity assessment.

Purpose of the Study:

• To evaluate the feasibility of T(2) mapping for muscle activity using ultrafast imaging (fast-mfMRI).
• To reduce image acquisition time compared to conventional mfMRI.
• To validate fast-mfMRI's ability to map exercise-induced muscle activation.

Main Methods:

• Employed fast-acquired mfMRI (fast-mfMRI) utilizing spin-echo echo-planar imaging (SE-EPI) for T(2) calculation and TrueFISP for morphology.
• Acquired images during and after 200 repetitions of ankle plantar flexion exercise in ten subjects.
• Fused functional T(2) images with morphological images to create final fast-mfMRI representations.

Main Results:

• Identical areas of activated muscle were observed in fast-mfMRI and SE-EPI images.
• Geometric localization in fast-mfMRI was consistent between morphological and functional images.
• The T(2) difference between rest and post-exercise states effectively served as a functional muscle activity map.

Conclusions:

• Fast-mfMRI is a feasible technique for T(2) mapping of exercise-induced muscle activity.
• This method significantly reduces scan duration, making it applicable to larger anatomical regions like the human trunk.
• Fast-mfMRI provides accurate functional and morphological information for muscle activity assessment.