Target Field Design for Magic Angle Gradient Coils

1999 ◽  
Vol 140 (1) ◽  
pp. 285-288 ◽  
Author(s):  
Thomas M. Barbara ◽  
Charles E. Bronnimann
Keyword(s):  
Magic Angle ◽  
Gradient Coils ◽  
Target Field

A new Target Field Method for Optimizing Longitudinal Gradient Coils' Property

PIERS Online ◽  
2007 ◽  
Vol 3 (6) ◽  
pp. 865-869 ◽  
Author(s):  
Feng Qi ◽  
Xin Tang ◽  
Zhe Jin ◽  
Le Wang ◽  
Donglin Zu ◽  
...  
Keyword(s):  
Field Method ◽  
Gradient Coils ◽  
Longitudinal Gradient ◽  
Target Field

scholarly journals Design, Characterisation and Performance of an Improved Portable and Sustainable Low-Field MRI System

2021 ◽  
Vol 9 ◽  
Author(s):  
Bart de Vos ◽  
Javad Parsa ◽  
Zaynab Abdulrazaq ◽  
Wouter M. Teeuwisse ◽  
Camille D. E. Van Speybroeck ◽  
...  
Keyword(s):  
Eddy Currents ◽  
Point Of Care ◽  
Low Frequency ◽  
Gradient Coils ◽  
Rf Amplifier ◽  
Target Field ◽  
Low Field ◽  
Gradient Amplifier ◽  
And Performance

Low-field permanent magnet-based MRI systems are finding increasing use in portable, sustainable and point-of-care applications. In order to maximize performance while minimizing cost many components of such a system should ideally be designed specifically for low frequency operation. In this paper we describe recent developments in constructing and characterising a low-field portable MRI system for in vivo imaging at 50 mT. These developments include the design of i) high-linearity gradient coils using a modified volume-based target field approach, ii) phased-array receive coils, and iii) a battery-operated three-axis gradient amplifier for improved portability and sustainability. In addition, we report performance characterisation of the RF amplifier, the gradient amplifier, eddy currents from the gradient coils, and describe a quality control protocol for the overall system.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

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