High-field NMR using resistive and hybrid magnets

Gan, Zhehong; Kwak, Hyung-Tae; Bird, M.D.; Cross, Timothy A.; Gor’kov, Peter L.; Brey, Wallace S.; Shetty, Kiran Kumar

doi:10.1016/j.jmr.2007.12.008

Cited by 36 publications

(21 citation statements)

References 30 publications

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“…In order to be able to further increase the (persistent) static (dc) magnetic field, i.e., sensitivity in NMR, hybrid magnet concepts have been pursued for some time [5,6]. Combining superconductors and resistive electromagnets, hybrid magnets allowed engineers to create a dc magnetic field of about 45 T, where the outer superconducting coil consists of three grades of Nb 3 Sn CICC and the resistive coil insert consists of four nested Florida-Bitter coils [6].…”

Section: Hybrid Magnets Back To the Futurementioning

confidence: 99%

“…Already, developments of ultra-high field hybrid MR systems (resistive and superconducting) are in progress [4,5], providing up to 45 Tesla (with 3 cm bore size), and which are used in material research [6]. To employ such high fields for analytical NMR or animal studies would require further improvements in field stability and homogeneity for larger bore diameters, as well as a significant reduction in costs for the magnet itself, installation and running costs.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

Moser

Laistler

Schmitt³

et al. 2017

Front. Phys.

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"History, of course, is difficult to write, if for no other reason, than that it has so many players and so many authors." -P. J. Keating (former Australian Prime Minister)Starting with post-war developments in nuclear magnetic resonance (NMR) a race for stronger and stronger magnetic fields has begun in the 1950s to overcome the inherently low sensitivity of this promising method. Further challenges were larger magnet bores to accommodate small animals and eventually humans. Initially, resistive electromagnets with small pole distances, or sample volumes, and field strengths up to 2.35 T (or 100 MHz 1 H frequency) were used in applications in physics, chemistry, and material science. This was followed by stronger and more stable (Nb-Ti based) superconducting magnet technology typically implemented first for small-bore systems in analytical chemistry, biochemistry and structural biology, and eventually allowing larger horizontal-bore magnets with diameters large enough to fit small laboratory animals. By the end of the 1970s, first low-field resistive magnets big enough to accommodate humans were developed and superconducting whole-body systems followed. Currently, cutting-edge analytical NMR systems are available at proton frequencies up to 1 GHz (23.5 T) based on Nb 3 Sn at 1.9 K. A new 1.2 GHz system (28 T) at 1.9 K, operating in persistent mode but using a combination of low and high temperature multi-filament superconductors is to be released. Preclinical instruments range from small-bore animal systems with typically 600-800 MHz (14.1-18.8 T) up to 900 MHz (21 T) at 1.9 K. Human whole-body MRI systems currently operate up to 10.5 T. Hybrid combined superconducting and resistive electromagnets with even higher field strength of 45 T dc and 100 T pulsed, are available for material research, of course with smaller free bore diameters. This rather costly development toward higher and higher field strength is a consequence of the inherently low and, thus, urgently needed sensitivity in all NMR experiments. This review particularly describes and compares the developments in superconducting magnet technology and, thus, sensitivity in three Moser et al.UHF MR-Magnet Technology fields of research: analytical NMR, biomedical and preclinical research, and human MRI and MRS, highlighting important steps and innovations. In addition, we summarize our knowledge on safety issues. An outlook into even stronger magnetic fields using different superconducting materials and/or hybrid magnet designs is presented.

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Section: Hybrid Magnets Back To the Futurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

Moser

Laistler

Schmitt³

et al. 2017

Front. Phys.

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“…In these systems, not only is the field often inhomogeneous, but temporal field fluctuations at frequencies far exceeding feasible field-frequencylock bandwidths may also be problematic. [10,25] The spatially encoded noise strategy described herein can be adapted to handle fluctuating fields in addition to static field inhomogeneity. Field fluctuations will affect all of the spectral lines identically and so their effects would appear to be amenable to deconvolution, and in fact deconvolution of such fluctuations has been demonstrated.…”

Section: Time-dependent Fieldsmentioning

confidence: 99%

“…Field fluctuations will affect all of the spectral lines identically and so their effects would appear to be amenable to deconvolution, and in fact deconvolution of such fluctuations has been demonstrated. [25,26] In order to carry out such a deconvolution knowledge of the field as a function of time is required during signal acquisition. Gan et al [25] obtained this information by collecting 1 H and 2 H spectra simultaneously while Iijima et al [26] used the induced electromotive force in a pickup coil.…”

Section: Time-dependent Fieldsmentioning

confidence: 99%

“…[25,26] In order to carry out such a deconvolution knowledge of the field as a function of time is required during signal acquisition. Gan et al [25] obtained this information by collecting 1 H and 2 H spectra simultaneously while Iijima et al [26] used the induced electromotive force in a pickup coil. One of these approaches could be employed here, where each transient would be deconvolved individually before any cross-correlation or other deconvolution steps.…”

Section: Time-dependent Fieldsmentioning

confidence: 99%

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Defeating Radiation Damping and Magnetic Field Inhomogeneity with Spatially Encoded Noise

Michal

2010

ChemPhysChem

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A simple NMR experiment capable of providing well resolved spectra under conditions where either radiation damping or static magnetic field inhomogeneity would broaden otherwise high-resolution NMR spectra is introduced. The approach involves using a strong pulsed magnetic field gradient and a selective radio-frequency pulse to encode a predetermined noise pattern into the spatial distribution of magnetization. Following readout in a much smaller field gradient, the noise sequence may be deconvolved from the acquired data and a high-resolution spectrum is obtained, eliminating the effects of either radiation damping or the static field inhomogeneity. In the presence of field inhomogeneity a field map is also obtained from the same single transient. A quasi-two-dimensional version of the experiment eliminates the need for deconvolution and produces improved results with simplified processing, but without requiring a full two-dimensional experiment. Example spectra are shown for both radiation damping and one-dimensional field inhomogeneity with improvement in linewidths of more than a factor of 40.

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Neue Ansätze zur Empfindlichkeitssteigerung in der biomolekularen NMR‐Spektroskopie

et al. 2015

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Im Frühling 2013 versammelten sich NMR‐Spektroskopiker am Weizmann‐Institut in Israel, um neue Ansätze zur Verbesserung der Empfindlichkeit von NMR‐Experimenten zu diskutieren, besonders im Hinblick auf Experimente an biomolekularen Systemen. Der vorliegende Aufsatz ist von vielen Autoren mit unterschiedlichem fachlichem Hintergrund verfasst worden; er beschreibt den Stand der Forschung auf diesem Gebiet, wie er im Rahmen des Treffens diskutiert wurde. Es werden Ansätze für Ultra‐Hochfeld‐NMR‐Spektroskopie, für neuartige Techniken der NMR‐Detektion, für Prinzipien und Methoden der Kernhyperpolarisation, aber auch für neue Probenpräparationsmethoden diskutiert. Diese Ansätze verbessern die Empfindlichkeit von NMR‐Experimenten im Festkörper und in Lösung, sind voneinander unabhängig und können sich in ihren Auswirkungen multiplizieren. Auch wenn in allen genannten Bereichen bereits substanzielle Verbesserungen erzielt wurden, ist doch noch eine weite Strecke zu überwinden, um an die Empfindlichkeiten von optischen und elektronischen Spektroskopien heranzureichen. Diese Probleme und erste Lösungsansätze werden ebenfalls diskutiert.

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High-field NMR using resistive and hybrid magnets

Cited by 36 publications

References 30 publications

Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

Defeating Radiation Damping and Magnetic Field Inhomogeneity with Spatially Encoded Noise

Neue Ansätze zur Empfindlichkeitssteigerung in der biomolekularen NMR‐Spektroskopie

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