Correction of environmental magnetic fields for the acquisition of Nuclear magnetic relaxation dispersion profiles below Earth’s field

Vasileios Zampetoulas (Corresponding Author), David J. Lurie, Lionel M. Broche

Research output: Contribution to journalArticle

7 Citations (Scopus)
4 Downloads (Pure)

Abstract

T1 relaxation times can be measured at a range of magnetic field strengths by Fast Field-Cycling (FFC) NMR relaxometry to provide T1-dispersion curves. These are valuable tools for the investigation of material properties as they provide information about molecular dynamics non-invasively. However, accessing information at fields below 230 μT (10 kHz proton Larmor frequency) requires careful correction of unwanted environmental magnetic fields.

In this work a novel method is proposed that compensates for the environmental fields on a FFC-NMR relaxometer and extends the acquisition of Nuclear Magnetic Relaxation Dispersion profiles to 2.3 μT (extremely low field region), with direct application in the study of slow molecular motions. Our method is an improvement of an existing technique, reported by Anoardo and Ferrante in 2003, which exploits the non-adiabatic behaviour of the magnetisation in rapidly-varying magnetic fields and makes use of the oscillation of the signal amplitude to estimate the field strength. This increases the accuracy in measuring the environmental fields and allows predicting the optimal correction values by applying simple equations to fit the data acquired. Validation of the method is performed by comparisons with well-known dispersion curves obtained from polymers and benzene.
Original languageEnglish
Pages (from-to)38-46
Number of pages8
JournalJournal of Magnetic Resonance
Volume282
Early online date22 Jul 2017
DOIs
Publication statusPublished - Sep 2017

Fingerprint

Magnetic relaxation
magnetic relaxation
Magnetic Fields
acquisition
Earth (planet)
Magnetic fields
field strength
profiles
magnetic fields
Nuclear magnetic resonance
nuclear magnetic resonance
cycles
curves
Molecular Dynamics Simulation
Benzene
Relaxation time
Molecular dynamics
Protons
Magnetization
Materials properties

Keywords

  • Fast Field-Cycling MRI
  • T1 dispersion
  • ultra-low field applications
  • MRI contrast

Cite this

Correction of environmental magnetic fields for the acquisition of Nuclear magnetic relaxation dispersion profiles below Earth’s field. / Zampetoulas, Vasileios (Corresponding Author); Lurie, David J.; Broche, Lionel M.

In: Journal of Magnetic Resonance, Vol. 282, 09.2017, p. 38-46.

Research output: Contribution to journalArticle

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abstract = "T1 relaxation times can be measured at a range of magnetic field strengths by Fast Field-Cycling (FFC) NMR relaxometry to provide T1-dispersion curves. These are valuable tools for the investigation of material properties as they provide information about molecular dynamics non-invasively. However, accessing information at fields below 230 μT (10 kHz proton Larmor frequency) requires careful correction of unwanted environmental magnetic fields.In this work a novel method is proposed that compensates for the environmental fields on a FFC-NMR relaxometer and extends the acquisition of Nuclear Magnetic Relaxation Dispersion profiles to 2.3 μT (extremely low field region), with direct application in the study of slow molecular motions. Our method is an improvement of an existing technique, reported by Anoardo and Ferrante in 2003, which exploits the non-adiabatic behaviour of the magnetisation in rapidly-varying magnetic fields and makes use of the oscillation of the signal amplitude to estimate the field strength. This increases the accuracy in measuring the environmental fields and allows predicting the optimal correction values by applying simple equations to fit the data acquired. Validation of the method is performed by comparisons with well-known dispersion curves obtained from polymers and benzene.",
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note = "V.Z. acknowledges funding from EPSRC under grant number EP/J500045/1, “A UK Magnetic Resonance Basic Technology Centre for Doctoral Training”. Aspects of the work were funded by EPSRC grant EP/K020293/1, “Zero-Field MRI to Enhance Diagnosis of Neurodegeneration”. This project has also received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 668119, project “IDentIFY”. The authors are grateful to Mr. G.P. Ashcroft and Dr. W. Mathieson for providing access to the biological samples used.",
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N2 - T1 relaxation times can be measured at a range of magnetic field strengths by Fast Field-Cycling (FFC) NMR relaxometry to provide T1-dispersion curves. These are valuable tools for the investigation of material properties as they provide information about molecular dynamics non-invasively. However, accessing information at fields below 230 μT (10 kHz proton Larmor frequency) requires careful correction of unwanted environmental magnetic fields.In this work a novel method is proposed that compensates for the environmental fields on a FFC-NMR relaxometer and extends the acquisition of Nuclear Magnetic Relaxation Dispersion profiles to 2.3 μT (extremely low field region), with direct application in the study of slow molecular motions. Our method is an improvement of an existing technique, reported by Anoardo and Ferrante in 2003, which exploits the non-adiabatic behaviour of the magnetisation in rapidly-varying magnetic fields and makes use of the oscillation of the signal amplitude to estimate the field strength. This increases the accuracy in measuring the environmental fields and allows predicting the optimal correction values by applying simple equations to fit the data acquired. Validation of the method is performed by comparisons with well-known dispersion curves obtained from polymers and benzene.

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