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Simulated phase evolution rewinding (SPHERE): a technique for reducing B0 inhomogeneity effects in MR images
1Department of Radiology, and Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis 55455, USA.
Magnetic Resonance in Medicine
|November 5, 1997
Summary
This study introduces a new method to correct magnetic resonance imaging (MRI) images distorted by magnetic field inhomogeneity (B0 inhomogeneity). The technique numerically rewinds phase data to produce clearer MRI images, applicable to various imaging sequences.
Area of Science:
- Medical Imaging
- Biophysics
- Image Processing
Background:
- Magnetic Resonance Imaging (MRI) is susceptible to image degradation.
- B0 field inhomogeneity causes phase accrual during data acquisition, leading to artifacts.
- Existing methods may not fully correct these distortions across all sequences.
Purpose of the Study:
- To present a novel numerical method for reducing B0 field inhomogeneity effects in MRI.
- To provide a theoretical analysis and demonstrate practical applications of the proposed technique.
- To validate the method's robustness across different MRI sequences.
Main Methods:
- A numerical phase rewinding technique is applied to k-space data.
- The method utilizes an initial image estimate and a corresponding field map.
- Corrected k-space data is Fourier transformed to reconstruct the final image.
Main Results:
- The method effectively reduces image degradation caused by B0 inhomogeneity.
- Demonstrated robustness across single-shot echo-planar imaging, segmented echo-planar imaging, and spiral sequences.
- Theoretical analysis confirms the general applicability of the technique.
Conclusions:
- The proposed numerical phase rewinding is a general and robust method for correcting B0 inhomogeneity artifacts in MRI.
- This technique can improve the quality of MRI images acquired with various pulse sequences.
- The findings offer a valuable tool for enhancing diagnostic accuracy in MRI.