Sample noise with circular surface coils

Harpen, Michael D.

doi:10.1118/1.596027

Cited by 49 publications

(28 citation statements)

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“…As shown in the third row, the maximum g-factor increased to 2.5 by only visiting six positions, and aliasing artifacts started to emerge in the reconstructed image. It is well known that the SNR is proportional to the square root of the number of channels [4,46]. To provide a fair comparison, an 8-channel RRFCA was simulated by combining two sets of sensitivity profiles of the 4-channel RRFCA with a 45˚ rotation.…”

Section: Resultsmentioning

confidence: 99%

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In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Jin

Zuo

et al. 2015

Journal of Magnetic Resonance

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Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) is capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo with the same number of coil elements, the RRFCA was able to reconstruct good quality images at a high reduction factor. It is hoped that the proposed sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

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Section: Resultsmentioning

confidence: 99%

“…The SNR is also proportional to the square root of the number of channels [4,68]. In order to provide a fair SNR comparison, we simulated the 8-channel RRFCA by combining data obtained with a 45˚ separation.…”

Section: Snr Calculationmentioning

confidence: 99%

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Jin

Zuo

et al. 2015

Journal of Magnetic Resonance

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“…The vector potential generated by the current in the coil can be assessed with Legendre polynomials (19), spherical harmonics (18), surface integrals (20), and Lipschitz-Hankel integral (21). All these methods require tedious calculations while a simple method based on the quasi-static approach proposed in this research activity, can be easily, mathematically implemented for circular coils sample induced resistance calculation.…”

Section: Electrical Conductivity Measurement In the Rf Rangementioning

confidence: 99%

“…So, we can assume that coils' self-inductances and capacities do not vary on loading and Eq. [18] is effectively a measure of R sample in terms of power dissipation.…”

Section: Estimation Of Electrical Conductivitysaline Solution Concentmentioning

confidence: 99%

An efficient method for electrical conductivity measurement in the RF range

Giovannetti

Frijia

Menichetti

et al. 2010

Concepts Magn Reson

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Many of the hardware procedure like radiofrequency (RF) coils testing and simulation experiments such as the estimation of temperature changes in magnetic resonance imaging experiments require saline phantoms. These kinds of experimental models are generally obtained using a well-defined container filled with conductive salt solution (i.e., diluted NaCl solution) or using a combination of conductive gel with a semi-solid consistency. These phantoms are commonly prepared according to the standards values of the principal parameter concerning theirs dielectric properties (i.e., permittivity and electrical conductivity). Although several permittivity measurement methods have already been reported in literature, most of the data describing the electrical conductivity of these saline solutions provided by different authors are often conflicting and the frequencies of each measure are not always specified. Besides, low-cost commercial conductimeters could provide measurements overlooking the conductivity dependence on the frequency, while the measurements in the RF range require costly coaxial probes which work with network analyzers with multi-electrodes working in solution. In this article, we describe a system based on self-made coil designed to measure the electrical conductivity of conductive solutions in the RF range, without any contact between the sample and the measurement probe. The estimated value of conductivity has been performed combining theoretical calculation of induced resistance in the phantom volume and experimental measurements using workbench instrumentations. The method can be applied to the whole RF range measurements by tuning the capacitor value of the resonant circuit.

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“…In addition, because they can detect RF signals along their entire length [10], they are also susceptible to body noise [17]. The effect on SNR of proximity to a conductive sample has been considered for conventional coils [18][19][20][21][22][23][24] but not for MI-based receivers.…”

Section: Introductionmentioning

confidence: 99%