Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Eddy Currents

Eddy Currents

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...

Induced Electric Fields: Applications

Induced Electric Fields: Applications

An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge distribution. Specifically, the induced electric field is nonconservative because it does not work in moving a charge over a closed path. In contrast, the electrostatic field is conservative and does no net work over a closed path. Hence, electric potential can be associated with the electrostatic field but not the induced field. The following...

What is an Electrochemical Gradient?

What is an Electrochemical Gradient?

Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.
The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an...

Gradient and Del Operator

Gradient and Del Operator

In mathematics and physics, the gradient and del operator are fundamental concepts used to describe the behavior of functions and fields in space. The gradient is a mathematical operator that gives both the magnitude and direction of the maximum spatial rate of change. Consider a person standing on a mountain. The slope of the mountain at any given point is not defined unless it is quantified in a particular direction. For this reason, a "directional derivative" is defined, which is a vector...

Divergence and Curl of Electric Field

Divergence and Curl of Electric Field

The divergence of a vector is a measure of how much the vector spreads out (diverges) from a point. For example, an electric field vector diverges from the positive charge and converges at the negative charge. The divergence of an electric field is derived using Gauss's law and is equal to the charge density divided by the permittivity of space. Mathematically, it is expressed as

Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)

Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)

Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Scout-based Multi-Echo NAvigator (SMENA) for high temporal resolution motion and B <sub>0</sub> estimation and correction: applications to multi-echo GRE and EPTI.

bioRxiv : the preprint server for biology·2026

Same author

Diffusion-weighted Imaging of the Liver: Primed for New Business.

Radiology·2026

Same author

Accelerating MRI With Longitudinally-Informed Latent Posterior Sampling.

Magnetic resonance in medicine·2026

Same author

A Dynamic Shim Approach for Correcting Eddy Current Effects in Diffusion-Prepared MRI Acquisition Using a Multi-Coil AC/DC Shim-Array.

Magnetic resonance in medicine·2026

Same author

In Vivo Meso-Scale Whole-Brain Quantitative Imaging With Tailored MRF on the NexGen 7T Scanner.

Magnetic resonance in medicine·2025

Same author

Stretched Radial Trajectory Design for Efficient MRI with Enhanced K-Space Coverage and Image Resolution.

Bioengineering (Basel, Switzerland)·2025

Same journal

A Comparison of Tissue Property Values Estimated Using Conventional Cardiac MRF and MT-Cardiac MRF.

Magnetic resonance in medicine·2026

Same journal

Dependence of the Extra-Cellular Diffusion Coefficient on the Fractions of Neurites and Cell Bodies in Gray Matter.

Magnetic resonance in medicine·2026

Same journal

Triple-Pulse <sup>23</sup>Na MRI Sequence (TriNa) for Simultaneous Acquisition of Spin-Density-Weighted and Fluid-Attenuated Images.

Magnetic resonance in medicine·2026

Same journal

Evaluation of Phantom Doping Materials in Quantitative Susceptibility Mapping.

Magnetic resonance in medicine·2026

Same journal

Design of an 8-Channel Transmit 32-Channel Receive 11.7T Head Coil and Evaluation of SNR Gains.

Magnetic resonance in medicine·2026

Same journal

The Potential for Absolute Temperature Imaging Based on Brain Metabolites Using an FID-Shifting Approach in Gradient Echo Planar Spectroscopic Imaging (GREPSI).

Magnetic resonance in medicine·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Jun 30, 2025

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors

Published on: January 16, 2020

Pre-excitation gradients for eddy current nulled convex optimized diffusion encoding (Pre-ENCODE).

Matthew J Middione¹, Michael Loecher¹, Xiaozhi Cao¹

¹Department of Radiology, Stanford University, Stanford, California.

Magnetic Resonance in Medicine

|March 19, 2024

Summary

This summary is machine-generated.

Pre-excitation gradients for eddy current-nulled convex optimized diffusion encoding (Pre-ENCODE) significantly reduce image distortions in diffusion-weighted MRI. This novel method achieves shorter echo times compared to traditional monopolar and ENCODE sequences.

Keywords:

diffusion eddy currents time‐optimal

More Related Videos

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

Published on: May 7, 2017

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient Echo Quantum Memory in Warm Atomic Vapor

Published on: November 11, 2013

Related Experiment Videos

Last Updated: Jun 30, 2025

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors

Published on: January 16, 2020

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

External Excitation of Neurons Using Electric and Magnetic Fields in One- and Two-dimensional Cultures

Published on: May 7, 2017

Gradient Echo Quantum Memory in Warm Atomic Vapor

Gradient Echo Quantum Memory in Warm Atomic Vapor

Published on: November 11, 2013

Area of Science:

Magnetic Resonance Imaging
Diffusion-Weighted Imaging
Image Distortion Correction

Background:

Eddy currents are a significant source of image distortion in diffusion-weighted MRI (DWI).
Existing methods like monopolar (MONO) and ENCODE sequences have limitations in mitigating these distortions and achieving short echo times.
Minimizing echo time (TE) is crucial for reducing T2-weighted artifacts and improving image quality in DWI.

Purpose of the Study:

To evaluate the efficacy of pre-excitation gradients for eddy current-nulled convex optimized diffusion encoding (Pre-ENCODE) in reducing eddy current-induced distortions in DWI.
To compare the performance of Pre-ENCODE against conventional MONO and ENCODE sequences in terms of echo time and image distortion.

Main Methods:

Diffusion-weighted MRI sequences including MONO, ENCODE, and Pre-ENCODE were assessed.
Evaluation involved simulations, phantom experiments, and in vivo DWI in human volunteers.
Key metrics included minimum achievable echo time (TE) and estimation of eddy current-induced image distortions via intravoxel signal variance.

Main Results:

Pre-ENCODE consistently achieved shorter echo times (TE) than both MONO and ENCODE across various b-values and spatial resolutions in simulations.
Image distortion, measured by intravoxel signal variance, was significantly lower with Pre-ENCODE compared to MONO and comparable to ENCODE.
In vivo measurements showed similar global brain apparent diffusion coefficients but reduced edge distortions with Pre-ENCODE compared to MONO.

Conclusions:

Pre-ENCODE effectively mitigates eddy current-induced image distortions in diffusion imaging.
The Pre-ENCODE technique offers a shorter echo time (TE) advantage over both MONO and ENCODE sequences.
This advancement holds promise for improving the accuracy and reliability of diffusion-weighted MRI.