Advancements in Gradient System Performance for Clinical and Research MRI

Abstract

In magnetic resonance imaging (MRI), spatial field gradients are applied along each axis to encode the location of the nuclear spin in the frequency domain. During recent years, the development of new gradient technologies has been focused on the generation of stronger and faster gradient fields for imaging with higher spatial and temporal resolution. This benefits imaging methods, such as brain diffusion and functional MRI, and enables human imaging at ultra-high field MRI. In addition to improving gradient performance, new technologies have been presented to minimize peripheral nerve stimulation and gradient-related acoustic noise, both generated by the rapid switching of strong gradient fields. This review will provide a general background on the gradient system and update on the state-of-the-art gradient technology.

The possible influence of third-order shim coils on gradient–magnet interactions: an inter-field and inter-site study

“…7, it appears that an undesired current circulates in the gradient coil which the GPA does not compensate for perfectly. More general details on GPAs for instance can be found in [5,6,15,[22][23][24].…”

“…A steady increase of image resolution in MRI has been occurring since its birth thanks to advancement in hardware including RF coils [1], gradient coils [2][3][4], their associated amplifiers [5,6], and magnets. After a leading effort by the Center for Magnetic Resonance Research to perform in vivo imaging at 10.5 T [7], now the highest magnetic field available for human studies is provided by a 11.7 T whole-body scanner, called Iseult, located in Saclay France [8], with a promise to reach higher Signal-to-Noise Ratio (SNR) [9,10] and, thus, higher spatio-temporal resolutions.…”

Practical considerations of diffusion-weighted MRS with ultra-strong diffusion gradients

“…Moreover, while our multiple-gradient-condition acquisition allowed reasonable comparisons with conventional gradient systems, a systematic repeatability study using independent gradient systems would be necessary to fully vindicate these results. Indeed, the Connectom gradient design differs from that of a lowergradient system, affecting gradient non-uniformity even at low gradient amplitudes, and cross-scanner comparisons would automatically include such differences (Gudino and Littin, 2023).…”

Nonlinear Gradient Field Mapping Using a Spherical Grid Phantom for 3 and 7 Tesla MR Imaging Systems Equipped with High-performance Gradient Coils

“…The gradient coil is designed to meet many conflicting requirements. [1][2][3][4] These requirements include maximum gradient strength, efficiency of gradient strength per unit current, inductance, DC resistance, slew rate, and spatial linearity (the area of the linear region). Vibration, noise, and peripheral nerve stimulation when driving the gradient coil are also important factors in the gradient design.…”