Distortion correction using topup algorithm by single k-space (TASK) for echo planar imaging.

Area of Science:

• Magnetic Resonance Imaging
• Image Processing
• Neuroimaging

Background:

• Echo planar imaging (EPI) is susceptible to distortions.
• Existing correction methods like topup require two EPI images with opposite distortions, necessitating additional scan time.
• B0 field maps are crucial for correcting EPI distortions.

Purpose of the Study:

• To introduce a novel algorithm, topup algorithm by single K-space (TASK), for correcting EPI distortions.
• To enable EPI distortion correction using data from a single k-space acquisition.
• To eliminate the need for additional scans for distortion correction.

Main Methods:

• The TASK algorithm utilizes centric EPI data, which inherently contains opposite phase-encoding polarities within a single k-space.
• The k-space is divided into two halves, and each half is processed to generate two input images for distortion correction.
• The procedure involves an iterative process of automatic brain masking and uniformity correction.

Main Results:

• TASK demonstrated comparable performance to traditional methods in correcting EPI distortions.
• High correlation was observed between field maps estimated by conventional topup and TASK.
• An ablation study validated the effectiveness of each step within the TASK algorithm.
• TASK proved effective for two-shot centric EPI distortion correction, indicating broader applicability.

Conclusions:

• TASK successfully corrects EPI distortions using information solely from a single k-space acquisition.
• The algorithm eliminates the requirement for additional scans, making the correction process more efficient.
• TASK offers a valuable, time-saving alternative for EPI distortion correction in various MRI applications.