Mapping eddy current induced fields for the correction of diffusion-weighted echo planar images

Area of Science:

• Magnetic Resonance Imaging
• Medical Physics
• Image Processing

Background:

• Diffusion-weighted echo-planar magnetic resonance imaging (DW-EPI) is crucial for diagnostics.
• Image distortion from eddy currents in DW-EPI causes misregistration and artifacts in quantitative diffusion images.

Purpose of the Study:

• To develop and validate a method for measuring eddy current-induced magnetic fields.
• To implement a correction scheme to reverse image distortions in DW-EPI.
• To assess the effectiveness of the correction for various imaging parameters.

Main Methods:

• Measured magnetic fields from eddy currents for orthogonal gradient pulse vectors.
• Calculated image distortion for arbitrary gradient amplitudes, directions, and slice orientations.
• Applied a correction method to reverse the ascertained image distortion, considering temporal and spatial dependencies.

Main Results:

• The correction scheme substantially reduced image distortion across arbitrary slice positions and angulations.
• The method effectively reversed distortions caused by eddy current-induced fields.
• Correction performance was independent of diffusion weighting and required no additional scanning time.

Conclusions:

• The presented method effectively measures and corrects eddy current-induced image distortions in DW-EPI.
• This technique enhances the accuracy of quantitative diffusion imaging, particularly for single-shot EPI.
• The correction is robust, efficient, and suitable for clinical application without increasing scan duration.