Reduced field-of-view MRI using outer volume suppression for spinal cord diffusion imaging

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Spinal Cord Imaging

Background:

• Diffusion-weighted imaging (DWI) is crucial for spinal cord evaluation.
• Susceptibility effects and motion artifacts degrade spinal cord DWI quality at high field strengths (3T).
• Existing techniques struggle to simultaneously address these artifacts.

Purpose of the Study:

• To develop and validate a novel spin-echo single-shot echo-planar imaging (SS-EPI) technique.
• To reduce susceptibility effects and motion artifacts in 3T spinal cord DWI.
• To improve image quality and clinical applicability of spinal cord DWI.

Main Methods:

• Implementation of a reduced field of view (FOV) in the phase-encoding direction.
• Utilizing an outer volume suppression (OVS) sequence to minimize aliasing.
• Employing a slice-selection gradient-reversal technique for effective fat suppression.
• Optimization of OVS via numerical simulations considering T(1) relaxation and B(1) variations.
• In vitro and in vivo evaluation of the optimized sequence.

Main Results:

• Simulations demonstrated OVS suppression to <0.25% (optimal) and ~3% (worst-case).
• In vitro measurements showed a mean residual signal of <0.95% +/- 0.42.
• In vivo scans achieved artifact-free images with 0.9 x 1.05 mm(2) in-plane resolution.
• The technique significantly reduces susceptibility and motion artifacts.

Conclusions:

• The developed SS-EPI technique effectively minimizes artifacts in 3T spinal cord DWI.
• The optimized OVS and fat suppression strategies enhance image quality.
• The short acquisition time makes this technique highly promising for clinical applications and research.