Compact magnets for magnetic resonance

Demas, Vasiliki; Prado, Pablo J.

doi:10.1002/cmr.a.20131

Cited by 33 publications

(9 citation statements)

References 26 publications

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“…Tabletop relaxometers employ magnets constructed with the aim of providing maximum field homogeneity in a field region enclosed by at least three of the six sides of a cuboid (Fig. 3a, b) [18][19][20], while compact sensors that derive from mobile well-logging tools require a field gradient to collect the NMR signal from a sensitive volume localized outside the magnet ( Fig. 3c, d) [21][22][23][24][25].…”

Section: Magnets and Instrumentsmentioning

confidence: 99%

Mobile and Compact NMR

Blümich

2016

Modern Magnetic Resonance

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NMR with mobile and compact devices is experiencing considerable growth in recent years in particular since instruments have become available, which are capable not only of measuring NMR relaxation but also images and highresolution spectra. Based on permanent magnet technology, compact tabletop NMR instruments measure samples of materials and solutions positioned inside the magnet, while compact mobile instruments measure material properties of intact objects and samples nondestructively in the inhomogeneous stray field outside the magnet. Following a brief introduction to NMR with homogeneous and inhomogeneous magnetic fields and to the concepts of permanent center-and stray-field NMR magnets, the evolution of the technology over the past 10 years is reviewed and illustrated with selected applications. Relaxation and diffusion measurements find use in the analysis of foods, biological tissues, polymer materials, porous media, and objects of cultural heritage. Compact imaging

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Section: Magnets and Instrumentsmentioning

confidence: 99%

Mobile and Compact NMR

Blümich

2016

Modern Magnetic Resonance

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“…A detailed and comprehensive review of many single‐sided and other portable magnet configurations can be found in References , , and . Our group has also studied single‐sided magnet designs .…”

Section: Introductionmentioning

confidence: 99%

A portable single‐sided magnet system for remote NMR measurements of pulmonary function

et al. 2014

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In this work, we report initial results from a light-weight, low field magnetic resonance device designed to make relative pulmonary density measurements at the bedside. The development of this device necessarily involves special considerations for the magnet, RF and data acquisition schemes as well as a careful analysis of what is needed to provide useful information in the ICU. A homogeneous field region is created remotely from the surface of the magnet such that when the magnet is placed against the chest, an NMR signal is measured from a small volume in the lung. In order to achieve portability, one must trade off field strength and therefore spatial resolution. We report initial measurements from a ping-pong ball size region in the lung as a function of lung volume. As expected, we measured decreased signal at larger lung volumes since lung density decreases with increasing lung volume. Using a CPMG sequence with ΔTE=3.5 ms and a 20 echo train, a signal to noise ratio ~1100 was obtained from an 8.8mT planar magnet after signal averaging for 43 s. This is the first demonstration of NMR measurements made on a human lung with a light-weight planar NMR device. We argue that very low spatial resolution measurements of different lobar lung regions will provide useful diagnostic information for clinicians treating Acute Respiratory Distress Syndrome as clinicians want to avoid ventilator pressures that cause either lung over distension (too much pressure) or lung collapse (too little pressure).

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“…Different methodologies of passive shimming are being developed by a number of research and development groups, and there have been remarkable improvements in field homogeneity, especially in the fields of portable NMR/MRI with single-sided [11][12][13][14][15][16] and closed [17][18][19][20][21][22] 3 permanent magnets. The details including instrumentations and applications are reviewed elsewhere [23][24][25][26]. For example, the use of shim units built from movable permanent blocks and fine control of their positioning allow sub-ppm spectroscopic resolution sufficient to measure 1 H NMR spectra, in a single-sided magnet [13] and in a Halbach closed magnet [20].…”

Section: Introductionmentioning

confidence: 99%

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

Terada

Kono

Ishizawa

et al. 2013

Journal of Magnetic Resonance

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We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming.

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Compact magnets for magnetic resonance

Cited by 33 publications

References 26 publications

Mobile and Compact NMR

Mobile and Compact NMR

A portable single‐sided magnet system for remote NMR measurements of pulmonary function

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

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