Progress in high field MRI at the University of Florida

Beck, B.; Plant, David R.; Grant, Samuel C.; Thelwall, Peter E.; Silver, X.; Mareci, Tom; Benveniste, Helene; Smith, M. D.; Collins, Christopher M.; Crozier, Stuart; Blackband, S. J.

doi:10.1007/bf02678590

Cited by 16 publications

(6 citation statements)

References 13 publications

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“…If such preamplifiers are to be used, they must also be placed very close to the coils (in order to minimize line loss due to impedance mismatches), which is difficult to implement given the limited space available. Two papers have been published which have showed the feasibility of phased-array imaging at a proton frequency of 200 MHz [27,28], although these were implemented with a wide-bore horizontal magnet. These designs used array loops with dimensions approximately 3.8 Â 5 cm.…”

Section: Introductionmentioning

confidence: 98%

Design of a capacitively decoupled transmit/receive NMR phased array for high field microscopy at 14.1T

Zhang

Webb

2004

Journal of Magnetic Resonance

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Section: Introductionmentioning

confidence: 98%

Design of a capacitively decoupled transmit/receive NMR phased array for high field microscopy at 14.1T

Zhang

Webb

2004

Journal of Magnetic Resonance

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“…While B 0 fields in animal scanners exceed 11 T [1], the industry presently offers compactly built, actively shielded MR scanners suitable for clinical routine diagnostics with 3 T field strength.…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T

et al. 2003

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The increasing availability of high-field (3 T) MR scanners requires adapting and optimizing clinical imaging protocols to exploit the theoretically higher signal-to-noise ratio (SNR) of the higher field strength. Our aim was to establish reliable and stable protocols meeting the clinical demands for imaging the neurocranium at 3 T. Two hundred patients with a broad range of indications received an examination of the neurocranium with an appropriate assortment of imaging techniques at 3 T. Several imaging parameters were optimized. Keeping scan times comparable to those at 1.5 T we increased spatial resolution. Contrast-enhanced and non-enhanced T1-weighted imaging was best applying gradient-echo and inversion recovery (rather than spin-echo) techniques, respectively. For fluid-attenuated inversion recovery (FLAIR) imaging a TE of 120 ms yielded optimum contrast-to-noise ratio (CNR). High-resolution isotropic 3D data sets were acquired within reasonable scan times. Some artifacts were pronounced, but generally imaging profited from the higher SNR. We present a set of optimized examination protocols for neuroimaging at 3 T, which proved to be reliable in a clinical routine setting.

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“…Using Eqs. [1][2][3][4] and assuming T S ϭ 310 K and T C,RT ϭ 293 K, the effect of coil cooling on the SNR (with respect to the SNR at 100 MHz and 0K) and the resulting gain in SNR as compared to the performance at RT have been estimated as a function of resonance frequency ( Fig. 1).…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The SNR per unit time can be increased by either increasing the numerator, i.e., the magnetic polarization by using higher static magnetic field strengths or hyperpolarization of certain nuclei (1,2) or, alternatively, by decreasing the denominator, the noise power. High magnetic field strengths B 0 of up to 17.6 T have been used in small animal MRI (3). However, such systems are not only expensive, but also involve methodological challenges: images are prone to susceptibility artifacts caused by tissue heterogeneity, relaxation times change unfavorably, and (RF) power dissipation in the subject becomes an issue.…”

mentioning

confidence: 99%

Performance of a 200‐MHz cryogenic RF probe designed for MRI and MRS of the murine brain

Ratering

Baltes

Nordmeyer-Massner

et al. 2008

Magnetic Resonance in Med

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A cryogenic 200-MHz RF transmit/receive probe (CryoProbe) made of copper and designed for murine brain studies is described. The probe operates at 30K and its performance was compared to a home-made surface coil of equal dimensions and a mouse head volume resonator, both operating at room temperature (RT). Since for small volumes of tissue interrogated (<5 mL) sample noise and thermal noise of the receiver are of comparable magnitude, considerable noise reduction can be achieved by cooling of the receiver system, e.g., using cold helium gas. The effect of temperature lowering on the signal-to-noise ratio (SNR) was assessed in phantom and in vivo murine brain studies using conventional MRI sequences (spin and gradient echo) and single voxel MR spectroscopy. Consistent sensitivity increases were observed for the CryoProbe. SNR increases by a factor ≥2 for the phantom experiments and by factors of 1.8 to 1.9 for in vivo experiments when compared to the RT surface coil for both MRI and MRS experiments. These results are in good agreement with estimated SNR gains for a circular surface coil probe cooled to 30K. The use of a cryogenic probe represents an economically attractive option to enhance the sensitivity in small animal MRI/MRS.

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Progress in high field MRI at the University of Florida

Cited by 16 publications

References 13 publications

Design of a capacitively decoupled transmit/receive NMR phased array for high field microscopy at 14.1T

Design of a capacitively decoupled transmit/receive NMR phased array for high field microscopy at 14.1T

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T

Performance of a 200‐MHz cryogenic RF probe designed for MRI and MRS of the murine brain

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