Compensation of gradient-induced magnetic field perturbations

Robust Compensation of Magnetic Field perturbations for Localized Spectroscopy Applications

Introduction Weak water suppression is used in some localized proton (H) spectroscopy applications, so that a considerable amount of water signal remains and can be used for various purposes. In these cases the spectra might suffer from sidebands of residual water signal caused by coil vibrations. Various methods have been published previously [1-4] to eliminate these sidebands. But most of the...

Quantification and compensation of eddy-current-induced magnetic-field gradients.

Two robust techniques for quantification and compensation of eddy-current-induced magnetic-field gradients and static magnetic-field shifts (ΔB0) in MRI systems are described. Purpose-built 1-D or six-point phantoms are employed. Both procedures involve measuring the effects of a prior magnetic-field-gradient test pulse on the phantom's free induction decay (FID). Phantom-specific analysis of t...

Magnetic field generation from cosmological perturbations.

In this Letter, we discuss the generation of magnetic field from cosmological perturbations. We consider the evolution of three component plasma (electron, proton, and photon) evaluating the collision term between electrons and photons up to the second order. The collision term is shown to induce electric current, which then generates magnetic field. There are three contributions, two of which ...

Ultra-low field magnetic resonance imaging detection with gradient tensor compensation in urban unshielded environment

Devices for gradient static magnetic field exposure.

We describe devices designed for magnetic field exposures in which field amplitude and gradients are controlled simultaneously. Dosimetry based on field continuation of high resolution magnetic field scans and numerical models is compared with validation measurements. The dosimetry variables we consider are based on the assumption that the biological or chemical system under study has field tra...