Laser-polarized 129Xe NMR at 1.88T and 8.5mT: a signal-to-noise ratio comparison

Cross, Albert R.; McDonald, M.; Robles, Juan Parra; Santyr, Giles

doi:10.1016/s1090-7807(03)00121-6

Cited by 13 publications

(24 citation statements)

References 12 publications

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“…[2]) of the 129 Xe signals obtained from the three rats was 80 6 8 ms. As expected, the improved homogeneity following optimal mechanical and resistive shimming combined with the low field yielded relatively long T Ã 2 values compared to higher fields (<10 ms) (6,16). This T Ã 2 estimate is in good agreement with values found in the literature at similar field strengths (6,9,23) and is approximately the same as measured in the phantoms confirming that transverse relaxation of HNG in the lung at 73.5 mT is mainly due to the magnetic field inhomogeneities and not due to the intrinsic tissue susceptibility (11,16,41). This confirms that T Ã 2 will likely be longer with more careful shimming.…”

Section: Resultssupporting

confidence: 89%

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

Dominguez‐Viqueira

Parra‐Robles

Fox

et al. 2008

Concepts Magn Reson

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Hyperpolarized Noble Gas (HNG), 3 He (helium) or 129 Xe (xenon), MR imaging has become a promising approach for visualizing lung anatomy and function. It has been theoretically predicted that low field strengths (0.05-0.2 T) may provide optimal signal-to-noise ratio (SNR) and spatial resolution for clinical HNG MR imaging. These optimum field strengths correspond to frequencies between 1.62-6.5 MHz and 0.59-2.35 MHz for 3 He and 129 Xe respectively. The optimum field strength depends on the size and geometry of the sample and radiofrequency (RF) coil as well as the field dependence of the HNG MR properties in the lung (e.g., relaxation times, susceptibility effects). In particular, little is known about the field dependence of the apparent transverse relaxation time, T Ã 2 , which is expected to strongly influence HNG signal. In this paper, a broadband (0.1-100 MHz) variable field strength MR imaging system for rodents is described. A custom-built resistive magnet was constructed and shimmed to provide the necessary homogeneity for imaging. RF coils and transmit/receive switches for different frequencies were also developed. Preliminary proton ( 1 H) and hyperpolarized 129 Xe images of test objects are presented, including a desiccated lung phantom. In vivo 129 Xe signals from rat lungs were acquired at 73.5 mT and T Ã 2 was estimated to be approximately 80 6 8 ms, in good agreement with previously reported values. The MR system developed should be useful for imaging rodent lungs at different field strengths to verify the expected SNR and spatial resolution possible using HNG imaging and to investigate long range diffusion and oxygen-induced transverse relaxation.

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Section: Resultssupporting

confidence: 89%

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

Dominguez‐Viqueira

Parra‐Robles

Fox

et al. 2008

Concepts Magn Reson

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“…Hyperpolarized 3 He was dispensed from the polarizer into a TedlarV R bag (Jensen Inert Products, Coral Springs, FL) and transported to a Helmholtz pair holding magnet near the low-field system to preserve polarization until ready for use. Hyperpolarized 129 Xe gas was produced with a home-built, continuous flow polarizer, giving polarizations of 10-15% (29). The xenon polarizer employed natural abundance xenon gas (26.4% 129 Xe) in a gas mixture consisting of 1% Xe and 10% N 2 , balanced with 4 He.…”

Section: Hng Productionmentioning

confidence: 99%

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized ³He and ¹²⁹Xe at 74 mT

Kraayvanger

Bidinosti

Dominguez‐Viqueira

et al. 2010

Magnetic Resonance in Med

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Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, 3 He and 129 Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R 2 ) of 3 He at low magnetic field strengths (<0.1 T) in vivo. R 2 measurements can be achieved efficiently using the Carr-Purcell-Meiboom-Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr-PurcellMeiboom-Gill R 2 values of hyperpolarized 3 He and 129 Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for 3 He and 129 Xe were determined to be (5.2 6 0.6) 310 26 Pa 21 sec 21 and (7.3 6 0.4) 310 26 Pa 21 s 21 compared with spin-lattice relaxivity constants of (4.0 6 0.4) 310 26 Pa 21 s 21 and (4.3 6 1.3) 3 10 26 Pa 21 s 21 , respectively. In vivo experimental measurements of alveolar oxygen partial pressure using 3 He in whole rat lung show good agreement (r 2 5 0.973) with predictions based on lung volumes and ventilation parameters. For 129 Xe, multicomponent relaxation was observed with one component exhibiting an increase in R 2 with decreasing alveolar oxygen partial pressure. Magn Reson Med 64:1484-1490,

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“…Modifications to this design included quadrature phase detection and interfacing to the MR5000 console [2]. For the experiments at 8.5 mT, a solenoidal RF coil with a bore diameter of 10 mm, length of 12 mm (560 turns of 34 AWG coated copper wire), and tuned to 100 kHz was used as a field mapping probe and for homogeneity measurements.…”

Section: Mr Imaging and Xenon Polarization Systemsmentioning

confidence: 99%

“…While the very low field strengths available in the fringe field generally prohibits its use for most standard MR imaging applications, it may be suitable for hyperpolarized noble gas (HNG) MR imaging ( 129 Xe and 3 He). This is because, unlike conventional proton MR imaging where the signal-to-noise ratio (SNR) strongly depends on the field strength, the SNR of HNG MR imaging is less dependent on the field strength and more dependent on the laser polarization conditions, such as laser power and gas mixture [1,2].…”

Section: Introductionmentioning

confidence: 99%

Passive shimming of the fringe field of a superconducting magnet for ultra-low field hyperpolarized noble gas MRI

Parra‐Robles¹,

Cross²,

Santyr³

2005

Journal of Magnetic Resonance

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Laser-polarized 129Xe NMR at 1.88T and 8.5mT: a signal-to-noise ratio comparison

Cited by 13 publications

References 12 publications

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized ³He and ¹²⁹Xe at 74 mT

Passive shimming of the fringe field of a superconducting magnet for ultra-low field hyperpolarized noble gas MRI

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Laser-polarized 129Xe NMR at 1.88T and 8.5mT: a signal-to-noise ratio comparison

Cited by 13 publications

References 12 publications

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

A variable field strength system for hyperpolarized noble gas MR imaging of rodent lungs

Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT

Passive shimming of the fringe field of a superconducting magnet for ultra-low field hyperpolarized noble gas MRI

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Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized ³He and ¹²⁹Xe at 74 mT