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Gradient pre-emphasis to counteract first-order concomitant fields on asymmetric MRI gradient systems.
Shengzhen Tao1,2, Paul T Weavers1, Joshua D Trzasko1
1Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
Magnetic Resonance in Medicine
|July 5, 2016
Summary
This study introduces a gradient pre-emphasis technique to correct for magnetic field distortions caused by asymmetric gradient systems in MRI. The method effectively prevents image artifacts, improving diagnostic accuracy.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Gradient Coil Systems
- Image Artifact Correction
Background:
- Asymmetric gradient systems in MRI introduce first-order concomitant fields.
- These fields cause significant phase errors and image distortions, compromising image quality.
Purpose of the Study:
- To develop a gradient pre-emphasis scheme to prospectively counteract first-order concomitant field effects.
- To demonstrate the effectiveness of this scheme through real-time implementation on a compact gradient system.
Main Methods:
- A generalized gradient pre-emphasis model was developed for arbitrary gradient waveforms.
- A computationally simple, hardware-compatible approximate solution was derived.
- The method was implemented and tested in real-time using phantom and in vivo data with various imaging sequences.
Main Results:
- First-order concomitant fields were shown to induce substantial phase errors and spatially dependent blurring/distortion in MRI data.
- The proposed gradient pre-emphasis effectively prevented these artifacts in phantom and in vivo experiments.
Conclusions:
- An efficient and effective gradient pre-emphasis framework was developed.
- This framework successfully counteracts the effects of first-order concomitant fields in asymmetric gradient systems.
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