3D gradient coil design for open MRI systems

While, Peter T.; Forbes, Lawrence K.; Crozier, Stuart

doi:10.1016/j.jmr.2010.08.017

Cited by 13 publications

(9 citation statements)

References 38 publications

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“…By modifying the magnetic field seen at a given position, one modifies the rate of precession of protons as a function of position, allowing one to determine the position of a given proton. These gradient fields are generated using special gradient coils that are embedded into the bore of the magnet (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54). A gradient coil is designed so that the gradient varies as linearly with position as possible, but a gradient that is linear across the entire field of view (FOV) is not always achievable (55), due to the requirement that gradient fields be generated with a very short rise time, typically less than 200 µs.…”

Section: Gradient Nonlinearitiesmentioning

confidence: 99%

See 1 more Smart Citation

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

Weygand

Fuller

Ibbott

et al. 2016

International Journal of Radiation Oncology*Biology*Physics

128

202

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Section: Gradient Nonlinearitiesmentioning

confidence: 99%

“…Variation of maximum geometric distortion as a function of field strength for data reported by Stanescu et al(54) andWachowicz et al (68). Since three field strengths were…”

mentioning

confidence: 96%

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

Weygand

Fuller

Ibbott

et al. 2016

International Journal of Radiation Oncology*Biology*Physics

128

202

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“…The field uniformity may be improved with technical refinements. The gradient coils of current open MRI scanners [29], [30] may be modified for omni-tomography. Figure 3 shows a possible configuration of gradient coils.…”

Section: Resultsmentioning

confidence: 99%

Towards Omni-Tomography—Grand Fusion of Multiple Modalities for Simultaneous Interior Tomography

et al. 2012

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We recently elevated interior tomography from its origin in computed tomography (CT) to a general tomographic principle, and proved its validity for other tomographic modalities including SPECT, MRI, and others. Here we propose “omni-tomography”, a novel concept for the grand fusion of multiple tomographic modalities for simultaneous data acquisition in a region of interest (ROI). Omni-tomography can be instrumental when physiological processes under investigation are multi-dimensional, multi-scale, multi-temporal and multi-parametric. Both preclinical and clinical studies now depend on in vivo tomography, often requiring separate evaluations by different imaging modalities. Over the past decade, two approaches have been used for multimodality fusion: Software based image registration and hybrid scanners such as PET-CT, PET-MRI, and SPECT-CT among others. While there are intrinsic limitations with both approaches, the main obstacle to the seamless fusion of multiple imaging modalities has been the bulkiness of each individual imager and the conflict of their physical (especially spatial) requirements. To address this challenge, omni-tomography is now unveiled as an emerging direction for biomedical imaging and systems biomedicine.

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“…There have been many publications outlining advances in the design of such bi-planar gradients. [27][28][29] In terms of gradient performance, typical numbers for modern-day gradients on the "whole body" low-field MRI systems are inductances on the order of 300-500 μH, resistances of 3-4 Ω, and efficiencies of 4-8 mT/m/A. Maximum gradient strengths for water-cooled gradient coils are on the order of 25 mT/m with a slew rate of 50 T/m/s.…”

Section: Gradient Designmentioning

confidence: 99%

Low‐field MRI: An MR physics perspective

Marques

Simonis

Webb

2019

Magnetic Resonance Imaging

230

266

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Historically, clinical MRI started with main magnetic field strengths in the ∼0.05–0.35T range. In the past 40 years there have been considerable developments in MRI hardware, with one of the primary ones being the trend to higher magnetic fields. While resulting in large improvements in data quality and diagnostic value, such developments have meant that conventional systems at 1.5 and 3T remain relatively expensive pieces of medical imaging equipment, and are out of the financial reach for much of the world. In this review we describe the current state‐of‐the‐art of low‐field systems (defined as 0.25–1T), both with respect to its low cost, low foot‐print, and subject accessibility. Furthermore, we discuss how low field could potentially benefit from many of the developments that have occurred in higher‐field MRI. In the first section, the signal‐to‐noise ratio (SNR) dependence on the static magnetic field and its impact on the achievable contrast, resolution, and acquisition times are discussed from a theoretical perspective. In the second section, developments in hardware (eg, magnet, gradient, and RF coils) used both in experimental low‐field scanners and also those that are currently in the market are reviewed. In the final section the potential roles of new acquisition readouts, motion tracking, and image reconstruction strategies, currently being developed primarily at higher fields, are presented. Level of Evidence : 5 Technical Efficacy Stage : 1 J. Magn. Reson. Imaging 2019.

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3D gradient coil design for open MRI systems

Cited by 13 publications

References 38 publications

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

Spatial Precision in Magnetic Resonance Imaging–Guided Radiation Therapy: The Role of Geometric Distortion

Towards Omni-Tomography—Grand Fusion of Multiple Modalities for Simultaneous Interior Tomography

Low‐field MRI: An MR physics perspective

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