Ultra-low field NMR measurements of liquids and gases with short relaxation times

Volegov, P. L.; Matlachov, A.N.; Kraus, R.H.

doi:10.1016/j.jmr.2006.07.021

Cited by 20 publications

(10 citation statements)

References 24 publications

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“…The spin physics is quite different in that limit, as the chemical-shift cannot be resolved, but the spin-spin couplings are still active and bear chemical information [407,677]. Bio-magnetic signals can be of the same order of magnitude as NMR signals at ultra-low fields, and the same detection technology can be used in both cases [678,679]. In porous media, the field inhomogeneities due to susceptibility differences across interfaces become negligible, and metal containers become transparent to electromagnetic waves [400].…”

Section: Discussionmentioning

confidence: 99%

Mobile single-sided NMR

Blümich

Perlo

Casanova

2008

Progress in Nuclear Magnetic Resonance Spectroscopy

431

299

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Section: Discussionmentioning

confidence: 99%

Mobile single-sided NMR

Blümich

Perlo

Casanova

2008

Progress in Nuclear Magnetic Resonance Spectroscopy

431

299

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“…The DSM method based on either a matrix pencils or equivalently a Hankel-TLS approach has been successfully applied in nuclear magnetic resonance imaging to estimate the temporal signal parameters of the free induction decay (FID) (Vanhuffel et al, 1994; Volegov et al, 2006; Barkhuijsen et al, 1987). The FID is directly modeled as a sum of decaying sinusoids, where the frequency and dampening factor of each sinusoid relates the underlying physical parameters.…”

Section: Discussionmentioning

confidence: 99%

“…We used a relatively modern approach to generating this model based on “matrix pencils” (Ikramov, 1993), or equivalently, the singular value decomposition (SVD) and total least squares (TLS) (Vanhuffel et al, 1994) of a Hankel matrix of the data. Although so-called “Prony analysis” has been studied for over a century (Kay and Marple, 1981; Marple, 1987), these more recent numerical methods have been successfully used to estimate or reconstruct unknown parameters of damped and undamped sinusoids in realistic noise (Hua and Sarkar, 1990), such as found in the free induction decay (FID) of nuclear magnetic resonance (Nieminen et al, 2010; Volegov et al, 2006). …”

Section: Methodsmentioning

confidence: 99%

The use of contact heat evoked potential stimulator (CHEPS) in magnetoencephalography for pain research

Gopalakrishnan

Machado

Burgess

2013

Journal of Neuroscience Methods

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Background Contact heat evoked potentials (CHEP) is a thermal stimulus modality used in pain research. We examine a commercial CHEP stimulator (CHEPS) that is designed to work in an fMRI environment, but poorly understood in the MEG environment. The CHEPS attains target temperatures rapidly using sophisticated control signals that unfortunately induce artifacts in the MEG. In this paper, we summarize our experiences using the CHEPS in MEG to study pain using an experimental paradigm, and propose a novel method for managing its artifact. New method We introduce a novel damped sinusoid modeling (DSM) technique to remove the CHEPS artifact based on estimates of the underlying sinusoids and damping factors. We show comparisons to signal space projection (SSP) and temporal signal space separation (tSSS) methods. Results The CHEPS artifact is highly dynamic, yet deterministic, switching rapidly from one frequency to another, with different spatial components. The galvanic connection between the subject and the CHEPS probe alters its performance, making pre-characterization difficult. Comparison with existing methods SSP methods failed to remove the artifact completely. TSSS performed better than SSP; however, tSSS requires the use of a multipolar head model that decreases the dimensionality and possibly the information content of the data. In contrast, DSM offers a strictly temporal modeling approach in which the artifact is estimated as a sum of damped sinusoids which is subtracted from the data. Conclusion Though the CHEPS increases the noise floor and introduces artifacts to the data, we believe the device can be successfully used in MEG if appropriate artifact removal techniques are followed.

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“…This greatly reduces the cost and complexity associated with large magnetic fields, typically produced by superconducting magnets, and has enabled applications such as the determination of uranium enrichment fraction via relaxation and/or J -coupling [3], [4], the combination with functional brain imaging via MEG [5] and detection of liquid explosives via relaxometry [6], [7]. …”

Section: Introductionmentioning

confidence: 99%

SQUIDs vs. Induction Coils for Ultra-Low Field Nuclear Magnetic Resonance: Experimental and Simulation Comparison

Matlashov

Schultz

Espy

et al. 2011

IEEE Trans. Appl. Supercond.

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Nuclear magnetic resonance (NMR) is widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging (MRI). Recently it has become possible to perform NMR and MRI in the ultra-low field (ULF) regime requiring measurement field strengths of the order of only 1 Gauss. This technique exploits the advantages offered by superconducting quantum interference devices or SQUIDs. Our group has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airport security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers may provide enough sensitivity in the 3–10 kHz range and can be used for fast liquid explosives detection based on ULF NMR technique. We describe experimental and computer-simulation results comparing multichannel SQUID based and induction coils based instruments that are capable of performing ULF MRI for liquid identification.

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Ultra-low field NMR measurements of liquids and gases with short relaxation times

Cited by 20 publications

References 24 publications

Mobile single-sided NMR

Mobile single-sided NMR

The use of contact heat evoked potential stimulator (CHEPS) in magnetoencephalography for pain research

SQUIDs vs. Induction Coils for Ultra-Low Field Nuclear Magnetic Resonance: Experimental and Simulation Comparison

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