Related Experiment Video
Updated: Oct 10, 2025
17:06
Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging
Published on: November 8, 2012
26.5K
Characterization and correction of time-varying eddy currents for diffusion MRI
Jake J Valsamis1,2, Paul I Dubovan1,2, Corey A Baron1,2
1Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
Magnetic Resonance in Medicine
|December 11, 2021
Summary
A new method, TVEDDY, effectively reduces artifacts from time-varying eddy currents in oscillating gradient spin-echo (OGSE) diffusion MRI. This significantly improves image quality for demanding MRI scans.
Area of Science:
- Magnetic Resonance Imaging
- Diffusion MRI
- Image Reconstruction
Background:
- Eddy currents in MRI can cause artifacts, particularly in gradient-intensive sequences like oscillating gradient spin-echo (OGSE).
- Time-varying eddy currents pose a challenge for artifact reduction in diffusion-weighted imaging.
- Accurate correction of eddy current-induced distortions is crucial for reliable diffusion MRI data.
Purpose of the Study:
- To develop and validate a novel retrospective method (TVEDDY) for correcting time-varying eddy current artifacts in diffusion MRI.
- To assess the performance of TVEDDY in reducing artifacts in oscillating gradient spin-echo (OGSE) and pulsed gradient spin echo (PGSE) sequences.
- To compare the efficacy of TVEDDY against conventional correction methods and field monitoring-based reconstruction.
Main Methods:
- An in-house algorithm, TVEDDY, was developed to retrospectively model eddy current decay using a three-parameter exponential decay model.
- Image pairs with opposite polarity diffusion gradients were acquired at 7 Tesla for both PGSE and OGSE sequences.
- Correction performance was evaluated using mean squared error (MSE) and compared to conventional methods and field monitoring-informed reconstruction.
Main Results:
- TVEDDY significantly reduced blurring artifacts in OGSE images, outperforming the traditional approach.
- For OGSE, TVEDDY demonstrated significantly lower MSE compared to the conventional correction method.
- Field monitoring-informed reconstruction yielded the lowest MSE for both PGSE and OGSE, but TVEDDY showed substantial improvements over conventional methods for OGSE.
Conclusions:
- Time-varying eddy currents can be effectively estimated directly from diffusion MRI data.
- The TVEDDY method offers substantial improvements in image quality for gradient-intensive diffusion MRI techniques like OGSE.
- Retrospective correction of eddy current effects is feasible and beneficial for advanced diffusion MRI applications.
Related Concept Videos
01:25Eddy Currents
1.8K
Since eddy currents occur only in conductors, magnets can separate metals from other materials. For example, in a recycling center, trash is dumped in batches down a ramp, beneath which lies a powerful magnet. Conductors in the trash are slowed by eddy currents, while nonmetals in the trash move on, separating from the metals. This works for all metals, not just ferromagnetic ones.
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
Other major applications of eddy currents appear in metal detectors and the braking systems of trains and roller...
1.8K
01:24Magnetic Resonance Imaging
7.9K
Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which matter exposed to magnetic fields and radio waves was found to emit radio signals. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. He applied for a patent for the first MRI scanning device in clinical use by the early 1980s. The early MRI...
7.9K
01:14NMR Spectrometers: Resolution and Error Correction
806
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
806
01:17Magnetic Damping
614
Eddy currents can produce significant drag on motion, called magnetic damping. For instance, when a metallic pendulum bob swings between the poles of a strong magnet, significant drag acts on the bob as it enters and leaves the field, quickly damping the motion.
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
614
01:28Magnetostatic Boundary Conditions
1.2K
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
1.2K