Progress Toward a Deployable SQUID-Based Ultra-Low Field MRI System for Anatomical Imaging

Espy, Michelle A.; Magnelind, Per E.; Matlashov, Andrei; Newman, Shaun; Sandin, Henrik; Schultz, L.; Sedillo, Robert; Urbaitis, Algis V.; Volegov, P. L.

doi:10.1109/tasc.2014.2365473

Cited by 33 publications

(34 citation statements)

References 17 publications

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“…This significantly increases the low-frequency noise with a typical 1/f-shaped spectrum [4,5]. We have observed significant 1/f noise below 6 kHz after niobium gradiometers were exposed to a 0.1 T field [6]. NbTi wire traps even more flux at lower magnetizing field and thus is impractical for ULF MRI systems.…”

Section: Introductionmentioning

confidence: 94%

Elimination of 1/ƒ Noise in Gradiometers for SQUID-Based Ultra-Low Field Nuclear Magnetic Resonance

Matlashov¹,

Magnelind²,

Volegov³

et al. 2015

2015 15th International Superconductive Electronics Conference (ISEC)

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Superconducting wire may trap magnetic flux after being exposed to strong magnetic fields, for example when used as gradiometer material in a SQUID-based ultra-low field nuclear magnetic resonance system. In this work we investigated noise caused by the dynamics of trapped flux in superconducting gradiometers made from different materials. Niobium (Nb), niobium-titanium (NbTi), and tantalum (Ta) wires were tested. Small wire-wound gradiometers were connected to a SQUID sensor. Nb and NbTi wires showed increasing 1/f noise after exposure to magnetic fields of 5 mT and above. A larger secondorder gradiometer made of Ta wire was tested inside a magnetically shielded room. A heating wire was placed on the outside of the Ta wire. Thermo-cycling of the Ta gradiometer significantly decreased the 1/f noise caused by its exposure to a magnetic field.

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Section: Introductionmentioning

confidence: 94%

Elimination of 1/ƒ Noise in Gradiometers for SQUID-Based Ultra-Low Field Nuclear Magnetic Resonance

Matlashov¹,

Magnelind²,

Volegov³

et al. 2015

2015 15th International Superconductive Electronics Conference (ISEC)

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“…Preliminary results of in vivo human brain imaging were demonstrated by the UC Berkeley group . Recently, researchers at the Los Alamos National Laboratory have built ULF‐MRI systems (two generations) that utilize Superconducting Quantum Interference Devices (SQUID) to compensate for the low SNR encountered at ULF . These systems leverage seven‐channel SQUIDs used with a prepolarizing field of 100 mT.…”

Section: Current State Of the Artmentioning

confidence: 99%

“…48 Recently, researchers at the Los Alamos National Laboratory have built ULF-MRI systems (two generations) that utilize Superconducting Quantum Interference Devices (SQUID) to compensate for the low SNR encountered at ULF. 49 These systems leverage sevenchannel SQUIDs used with a prepolarizing field of 100 mT. The image acquisition typically involves 3DFT methods with a resolution of 2.1 × 2.4 × 15 mm 3 , resulting in a total acquisition time of 67 minutes.…”

Section: Ulf Mri (<10 Mt)mentioning

confidence: 99%

Accessible magnetic resonance imaging: A review

Geethanath

Vaughan

2019

Magnetic Resonance Imaging

137

139

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The role of MRI in diagnostics, prognostics, and discoveries in basic sciences has been well established. However, access to this life‐saving technology is largely restricted to countries in upper‐middle to high‐income groups. In this article, we collate recent global MR scanner density data and group them into six geographical regions based on the WHO classification. We then analyze these data with respect to demographic factors such as population size, life expectancy, the percentage of internet users, and World Bank income grouping. We map these demographic factors to five dimensions or characteristics of accessible MRI, adapting definitions from the healthcare literature. With this background, the study then reviews recent demonstrations of accessible MRI categorized based on main magnetic field strength. We describe demonstrated examples for each of these categories, ranging from ultralow‐field to ultrahigh‐field MRI. Lastly, we review MR methods and associated developments impacting accessible MRI such as increasing/augmenting MR awareness and local expertise, incorporating hardware‐cognizant methods, rapid quantitative imaging, and leveraging innovations from adjacent fields. Level of Evidence: 5 Technical Efficacy Stage: 6 J. Magn. Reson. Imaging 2019.

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“…A practical implementation utilizing a Faraday coil as the detector for capsicum imaging in the earth's magnetic field was presented in 2006 [16]. Au unshielded 7-channel SQUID system was implemented by Espy et al in 2015 [17]. We began studying unshielded systems in an urban laboratory environment in 2008 [18].…”

Section: Introductionmentioning

confidence: 99%

Adaptive suppression of power line interference in ultra-low field magnetic resonance imaging in an unshielded environment

Huang

Dong

Qiu

et al. 2018

Journal of Magnetic Resonance

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Power-line harmonic interference and fixed-frequency noise peaks may cause stripeartifacts in ultra-low field (ULF) magnetic resonance imaging (MRI) in an unshielded environment and in a conductively shielded room. In this paper we describe an adaptive suppression method to eliminate these artifacts in MRI images. This technique utilizes spatial correlation of the interference from different positions, and is realized by subtracting the outputs of the reference channel(s) from those of the signal channel(s) using wavelet analysis and the least squares method. The adaptive suppression method is first implemented to remove the image artifacts in simulation. We then experimentally demonstrate the feasibility of this technique by adding three orthogonal superconducting quantum interference device (SQUID) magnetometers as reference channels to compensate the output of one 2 nd -order gradiometer. The experimental results show great improvement in the imaging quality in both 1D and 2D MRI images at two common imaging frequencies, 1.3 kHz and 4.8 kHz. At both frequencies, the effective compensation bandwidth is as high as 2 kHz. Furthermore, we examine the longitudinal relaxation times of the same sample before and after compensation, andshow that the MRI properties of the sample did not change after applying adaptive suppression. This technique can effectively increase the imaging bandwidth and be applied to ULF MRI in both an unshielded environment and a shielded room made from aluminum sheets.

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Progress Toward a Deployable SQUID-Based Ultra-Low Field MRI System for Anatomical Imaging

Cited by 33 publications

References 17 publications

Elimination of 1/ƒ Noise in Gradiometers for SQUID-Based Ultra-Low Field Nuclear Magnetic Resonance

Elimination of 1/ƒ Noise in Gradiometers for SQUID-Based Ultra-Low Field Nuclear Magnetic Resonance

Accessible magnetic resonance imaging: A review

Adaptive suppression of power line interference in ultra-low field magnetic resonance imaging in an unshielded environment

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