Diffusion tensor MRI of the spinal cord

Area of Science:

• Neuroimaging
• Biophysics
• Medical Physics

Background:

• Diffusion tensor imaging (DTI) is crucial for assessing white matter integrity.
• Spinal cord DTI presents unique challenges due to motion and anatomical complexity.
• Pulsed-field-gradient (PFG) techniques offer advanced diffusion measurements.

Purpose of the Study:

• To present apparent diffusion tensor (ADT) measurements of the spinal cord using a PFG multi-shot EPI sequence.
• To compare rotationally invariant anisotropy information with rotationally dependent methods.
• To evaluate the clinical applicability of ADT measurements in spinal pathologies.

Main Methods:

• Utilized a pulsed-field-gradient (PFG) multi-shot echo-planar imaging (EPI) sequence for spinal cord ADT measurements.
• Studied 10 healthy volunteers to characterize normal diffusion properties.
• Investigated 10 patients with cervical canal stenosis to assess diffusion changes in pathology.

Main Results:

• Demonstrated significantly higher water diffusivity parallel (approx. 2.5x) to spinal cord fibers compared to perpendicular directions.
• Observed cylindrically symmetric anisotropy characteristics in the spinal cord.
• Determined that a resolution of 1 mm in read and phase directions is necessary for unbiased ADT values.
• Showed that ADT changes in cervical canal stenosis were detectable even when conventional T1/T2 weighted imaging showed no lesion.

Conclusions:

• Spinal cord diffusion exhibits pronounced anisotropy, measurable with PFG-EPI ADT.
• High-resolution ADT imaging can robustly detect subtle spinal cord pathologies.
• This technique holds promise for improved clinical diagnosis of spinal cord diseases.