Design of internal MRI coils using ultimate intrinsic SNR

Eryaman, Yiğitcan; Oner, Yusuf; Atalar, Ergin

doi:10.1007/s10334-009-0167-1

Cited by 14 publications

(10 citation statements)

References 13 publications

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“…For a similar stripline element, Eryaman et al (13) have shown that the optimal intrinsic SNR can be obtained with a 4 cm length element. In our case, the stripline length is set to 6 cm to cover approximately the same area as the loop coil, while avoiding overlap between both elements.…”

Section: Discussionmentioning

confidence: 99%

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Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Castro

Bergen

Luijten

et al. 2011

Magnetic Resonance in Med

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1Higher magnetic field strengths like 7 T and above are desirable for MR spectroscopy given the increased spectral resolution and signal to noise ratio. At these field strengths, substantial nonuniformities in B 1 1/2 and radiofrequency power deposition become apparent. In this investigation, we propose an improvement on a conventionally used endorectal coil, through the addition of a second element (stripline). Both elements are used as transceivers. In the center of the prostate, approximately 40% signal to noise ratio increase is achieved. In fact, the signal to noise ratio gain obtained with the quadrature configuration locally can be even greater than 40% when compared to the single loop configuration. This is due to the natural asymmetry of the B 1 1/2 fields at high frequencies, which causes destructive and constructive interference patterns. Global specific absorption rate is reduced by almost a factor of 2 as expected. Furthermore, approximately a 4-fold decrease in local specific absorption rate is observed when normalized to the B 1 values in the center of the prostate. Because of the 4-fold local specific absorption rate decrease obtained with the dual channel setup for the same reference B 1 value (20 mT at 3.5 cm depth into the prostate) as compared to the single loop, the transmission power B 1 duty cycle can be increased by a factor 4. Consequently, when using the two-element endorectal coil, the radiofrequency power deposition is significantly reduced and radiofrequency intense sequences with adiabatic pulses can be safely applied at 7 T for 1 H magnetic resonance spectroscopy and MRI in the prostate. Altogether, in vivo 1 H magnetic resonance spectroscopic imaging of prostate cancer with a fully adiabatic sequence operated at a minimum B 1 1 of 20 mT shows insensitivity to the nonuniform transmit field, while remaining within local specific absorption rate guidelines of 10 W/kg. Magn Reson Med 68:311-318, 2012. V C 2011 Wiley Periodicals, Inc.

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Section: Discussionmentioning

confidence: 99%

“…A 6‐cm‐long stripline coil was fabricated using 3‐mm‐diameter copper litz wire as the active conductor, similar to the design presented by Eryaman et al (13). Litz wire obtained from the shield of a coaxial cable was flattened and used as the electric ground plane of the stripline element.…”

Section: Methodsmentioning

confidence: 99%

Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Castro

Bergen

Luijten

et al. 2011

Magnetic Resonance in Med

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“…At large radii, sensitivity tends to s/2πr 2 , where r 2 = x 2 + y 2 , and falls off with radial distance as 1/r 2 [9]. This variation can be corrected by multiplying the signal intensity of axial images by a correctly-centred function C(r 2 ) where r 2 = (x − x C ) 2 + (y − y C ) 2 and (x C , y C ) is the location of the coil axis (see e.g., [3]). However, there are peaks in sensitivity near the conductors that cannot easily be corrected.…”

Section: D Modelmentioning

confidence: 99%

“…Consequently, increased SNR can be obtained using coils with restricted fields of view (FOV), provided these match the target tissue [3], Many small internal coils have been developed for imaging lumens such as arteries, ducts and the gastrointestinal (GI) tract. For compatibility with clinical procedures these are normally based on endoscopes [4][5][6] or catheters [7][8][9][10], and devices for tracking have also been developed [11].…”

Section: Introductionmentioning

confidence: 99%

Magneto-Inductive Magnetic Resonance Imaging Duodenoscope

Syms¹,

Kardoulaki²,

Rea³

et al. 2017

PIER

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Abstract-A magnetic resonance imaging (MRI) duodenoscope is demonstrated, by combining nonmagnetic endoscope components with a thin-film receiver based on a magneto-inductive waveguide. The waveguide elements consist of figure-of-eight shaped inductors formed on either side of a flexible substrate and parallel plate capacitors that use the substrate as a dielectric. Operation is simulated using equivalent circuit models and by computation of two-and three-dimensional sensitivity patterns. Circuits are fabricated for operation at 127.7 MHz by double-sided patterning of copper-clad Kapton and assembled onto non-magnetic flexible endoscope insertion tubes. Operation is verified by bench testing and by 1 H MRI at 3T using phantoms. The receiver can form a segmented coaxial image along the length of the endoscope, even when bent, and shows a signal-to-noise-ratio advantage over a surface array coil up to three times the tube diameter at the tip. Initial immersion imaging experiments have been carried out and confirm an encouraging lack of sensitivity to RF heating.

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“…NTERNAL magnetic resonance imaging (MRI) using small coils has been demonstrated [1][2][3], but clinical acceptance is relatively slow. There are difficulties associated with delivery into the patient, MR compatibility of endoscopic tools and the non-uniform sensitivity of the coils.…”

Section: Introductionmentioning

confidence: 99%

SNR in MI Catheter Receivers for MRI

et al. 2016

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Design of internal MRI coils using ultimate intrinsic SNR

Abstract: An internal coil design method that takes advantage of the UISNR and optimum coil sensitivity calculations was presented. This method can also be used to design better internal MRI coils for different applications.

Cited by 14 publications

References 13 publications

Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Magneto-Inductive Magnetic Resonance Imaging Duodenoscope

SNR in MI Catheter Receivers for MRI

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Design of internal MRI coils using ultimate intrinsic SNR

Abstract: An internal coil design method that takes advantage of the UISNR and optimum coil sensitivity calculations was presented. This method can also be used to design better internal MRI coils for different applications.

Cited by 14 publications

References 13 publications

Improving SNR and B1 transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Improving SNR and B1 transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Magneto-Inductive Magnetic Resonance Imaging Duodenoscope

SNR in MI Catheter Receivers for MRI

Contact Info

Product

Resources

About

Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

Improving SNR and B₁ transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer