Presence of time-dependent diffusion in the brachial plexus

Area of Science:

• Magnetic Resonance Imaging
• Neuroscience
• Biophysics

Background:

• Diffusion MRI is sensitive to tissue microstructure.
• Understanding brachial plexus microstructure is crucial for diagnosing neurological conditions.
• Apparent diffusion coefficient (ADC) typically assumes diffusion is unrestricted.

Purpose of the Study:

• To develop and validate a method measuring diffusion time-dependent ADC in the brachial plexus.
• To assess the potential of this method for probing nerve microstructure.
• To investigate diffusion restriction in brachial plexus nerves.

Main Methods:

• Utilized diffusion-weighted MRI with body signal suppression for enhanced nerve visibility.
• Optimized sequence parameters for sensitivity to diffusion time variations.
• Applied a porous media-restricted diffusion model (Latour-Mitra equation) to ADC data.

Main Results:

• Observed a reduction in ADC at longer diffusion times, indicating restricted diffusion.
• Measured nerve T2 as 80 ± 5 ms.
• ADC varied from (1.5 ± 0.1) × 10⁻³ mm²/s at 18.3 ms to (1.0 ± 0.2) × 10⁻³ mm²/s at 81.3 ms diffusion time.

Conclusions:

• Successfully developed a novel method for assessing restricted diffusion in the brachial plexus.
• The method provides parameters comparable to those from other biological systems.
• This technique shows promise for non-invasively probing brachial plexus microstructure.