Water-fat separation in diffusion-weighted EPI using an IDEAL approach with image navigator

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging

Background:

• Diffusion-weighted MRI (DW-MRI) necessitates effective fat signal suppression.
• Conventional fat suppression methods can increase scan time or be suboptimal with magnetic field inhomogeneities.
• Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) offers robustness but is sensitive to motion-induced phase distortions.

Purpose of the Study:

• To introduce a novel method for robust fat suppression in echo planar-based DW-MRI using image navigators.
• To address limitations of existing fat suppression techniques in the presence of motion and field inhomogeneities.

Main Methods:

• A spin echo planar imaging (SE-EPI) diffusion-weighted sequence was modified to integrate IDEAL with an image navigator.
• The navigator corrects for phase effects caused by patient motion during diffusion-weighting gradients.
• Acquisitions were performed in phantoms and healthy volunteers across brain, pelvic, and abdominal regions.

Main Results:

• Diffusion-weighted IDEAL without navigator correction exhibited motion-induced artifacts.
• The integrated 2D navigator successfully corrected phase distortions, eliminating artifacts.
• Accurate water-fat separation was achieved even in the presence of motion.

Conclusions:

• Integrated image navigators enable robust water-fat separation in DW-EPI with IDEAL.
• This technique provides a time-efficient alternative to traditional fat-suppression methods in DW-MRI.
• The method demonstrates efficacy across various anatomical regions.