Correction of aliasing artifact in accelerated echo-planar imaging

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Image Reconstruction

Background:

• Echo-planar imaging (EPI) is crucial for functional MRI (fMRI) but suffers from artifacts.
• 2D Nyquist and aliasing artifacts degrade image quality and affect downstream analysis.
• Existing correction methods often address artifacts in isolation.

Purpose of the Study:

• To develop a unified reconstruction pipeline for simultaneous correction of 2D Nyquist and aliasing artifacts in EPI.
• To address artifacts across diverse EPI acquisition schemes (single-shot, multi-shot, parallel, multi-band).

Main Methods:

• Introduced a novel 2D Nyquist artifact correction extending a phase-search reconstruction.
• Generated phase-corrected images and used coil sensitivity profiles for optimal phase correction.
• Integrated a procedure to correct aliasing from 2D Nyquist effects, motion, and acceleration.

Main Results:

• Substantially reduced residual artifacts in EPI data, improving the ghost-to-signal ratio.
• Resulting default-mode network maps showed better alignment with reference networks.
• Outperformed conventional 1D Nyquist artifact correction methods.

Conclusions:

• The developed pipeline effectively corrects multiple aliasing artifact sources in EPI.
• Achieved improved image quality and functional sensitivity for various EPI acquisitions.
• Offers a comprehensive solution for EPI artifact correction in neuroimaging.