Related Experiment Videos
Correction of concomitant gradient artifacts in experimental microtesla MRI.
Whittier R Myers1, Michael Mössle, John Clarke
1Department of Physics, University of California, Berkeley, CA 94720-7300, USA. wmyers@berkeley.edu
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|September 20, 2005
Summary
Magnetic resonance imaging (MRI) artifacts at low fields are caused by concomitant gradients. New phase correction and precession field cycling methods effectively eliminate these distortions, improving image quality.
Area of Science:
- Physics
- Biophysics
- Medical Imaging
Background:
- Magnetic resonance imaging (MRI) is susceptible to artifacts from concomitant magnetic field gradients, particularly at very low static magnetic fields.
- These artifacts, including distortion and blurring, arise when gradient strength relative to sample size approaches static field strength.
- Investigating and correcting these artifacts is crucial for advancing low-field MRI applications.
Purpose of the Study:
- To investigate and correct artifacts caused by concomitant gradients in very low magnetic field MRI.
- To develop and validate novel algorithms for artifact reduction in low-field MRI.
- To explore the potential of integrating corrected low-field MRI with existing magnetoencephalography systems.
Main Methods:
- Acquired MR images of a phantom in a 66-microT field using gradients up to 350 microT/m.
- Employed a spin-echo pulse sequence with proton prepolarization and detection via a SQUID-coupled gradiometer.
- Developed and applied a post-acquisition phase correction algorithm and a precession field cycling technique.
Main Results:
- Concomitant gradients were identified as the cause of distortion and blurring artifacts in experimental and simulated images.
- A non-perturbative phase correction algorithm successfully eliminated concomitant gradient effects.
- Precession field cycling during phase encoding also corrected blurring artifacts, even with detector bandwidth limitations.
Conclusions:
- Concomitant gradient artifacts in low-field MRI can be effectively corrected using post-acquisition phase correction or precession field cycling.
- These correction techniques enhance image quality and enable the integration of MRI capabilities with existing SQUID systems for neuroscience research.
- The findings pave the way for improved low-field MRI systems and novel neuroimaging approaches.