Diffusion Tensor Imaging of Skeletal Muscle Contraction Using Oscillating Gradient Spin Echo.

Area of Science:

• Biomedical Engineering
• Musculoskeletal Imaging
• Diffusion Tensor Imaging

Background:

• Diffusion tensor imaging (DTI) assesses skeletal muscle in neuromuscular diseases.
• Conventional pulsed gradient spin echo (PGSE) DTI is limited to non-contracted muscles, hindering study of contraction mechanisms.
• Understanding muscle contraction is crucial for diagnosing neuromuscular disorders.

Purpose of the Study:

• To introduce and evaluate oscillating gradient spin echo (OGSE) DTI for assessing actively contracting skeletal muscle.
• To compare OGSE with conventional PGSE DTI in terms of signal voids and diffusivity measurements during muscle contraction.
• To explore the potential of OGSE DTI for diagnosing muscle contraction abnormalities.

Main Methods:

• Developed and tested two OGSE DTI sequences (25 Hz and 50 Hz).
• Scanned lower leg muscles (tibialis anterior, soleus) of five healthy volunteers during relaxation and active dorsiflexion/plantarflexion.
• Compared OGSE results with conventional PGSE DTI, analyzing signal voids and diffusivity values (axial and radial).

Main Results:

• OGSE significantly reduced signal voids in contracting tibialis anterior (dorsiflexion) and soleus (plantarflexion) compared to PGSE.
• PGSE yielded unrealistically high axial and radial diffusivity values during contraction.
• OGSE provided reduced and more reliable diffusivity values in actively contracting muscles.

Conclusions:

• DTI with OGSE diffusion encoding is feasible in human musculature, even during active contraction.
• OGSE mitigates signal voids and provides accurate diffusivity measurements in contracting muscles.
• OGSE DTI shows significant potential for assessing in-vivo muscle microstructural changes during contraction and diagnosing muscle diseases.