High-fidelity diffusion tensor imaging of the cervical spinal cord using point-spread-function encoded EPI.

Area of Science:

• Medical Imaging
• Neuroimaging
• Biophysics

Background:

• Spinal cord diffusion tensor imaging (DTI) faces challenges like small structure size and field inhomogeneity.
• These technical hurdles limit the clinical application of spinal cord DTI.
• Metallic implants further complicate DTI acquisition due to susceptibility artifacts.

Purpose of the Study:

• To achieve high-fidelity cervical spinal cord (CSC) DTI with improved signal-to-noise ratio (SNR) and acquisition efficiency.
• To evaluate the efficacy of a distortion-free multi-shot EPI technique, point-spread-function encoded EPI (PSF-EPI), for CSC DTI.
• To assess the clinical potential of PSF-EPI, particularly in the presence of metallic implants.

Main Methods:

• Utilized a distortion-free multi-shot EPI technique (PSF-EPI) for sagittal CSC DTI.
• Implemented tilted-CAIPI acceleration and partial Fourier undersampling to reduce scan time (six shots).
• Employed retrospective water/fat separation to remove unsuppressed fat signals and evaluated axial DTI quantitatively.

Main Results:

• Highly accelerated PSF-EPI demonstrated significant distortion reduction compared to multi-shot interleaved EPI.
• PSF-EPI showed superior anatomical consistency, even in patients with metallic implants.
• Quantitative DTI metrics from axial PSF-EPI scans were comparable to zonal oblique multi-slice EPI (ZOOM-EPI) and literature values.

Conclusions:

• PSF-EPI offers a promising solution for high-quality CSC diffusion imaging.
• The technique provides excellent anatomical consistency and quantitative reliability.
• Its practical scan time and performance with metallic implants suggest significant clinical potential for CSC DTI.