Magnetic resonance imaging of lungs at ultra-low magnetic field strenght using hyperpolarized 129Xe gas

Robles, Juan Parra

doi:10.22215/etd/2004-05912

Cited by 1 publication

(3 citation statements)

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“…Furthermore, 129 Xe provides similar spatial resolution with lower gradient intensities compared to 3 He and is soluble in tissue. This offers the additional capability of dissolved-phase imaging applications outside the gas spaces of the body (6,24).…”

Section: Resultsmentioning

confidence: 99%

“…4(a)] was designed and built to shield the imaging volume (i.e., gradient coil bore) rather than placing the entire system inside a large and expensive Faraday cage. The RF shield designed and constructed in this work was an open-ended cylinder, consisting of two layers of stainless steel mesh of 39 3 39 wires per square cm with wire diameter of 18.72 lm (McMaster-Carr, Chicago, IL) formed around an acrylic cylinder 130 cm long and 18 cm in outer diameter, designed to fit inside the bore of the gradient coil (24) [Fig. 4(a)].…”

Section: System Design and Constructionmentioning

confidence: 99%

“…Theoretically, the optimum field strength for clinical hyperpolarized gas lung imaging has been predicted by Parra-Robles et al (6,24) to lie between 0.05 and 0.2 T and depends on the gas type/mixture, sample/coil size, and geometry and field-dependence of the lung MR parameters, specifically T Ã 2 . Because of a decrease in T Ã 2 with increasing magnetic field strength, the SNR at clinical MR imaging field strengths (0.5-3.0 T) is predicted to be lower (20-50%) than at the predicted optimum fields for bandmatched imaging conditions.…”

Section: Introductionmentioning

confidence: 99%

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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: Resultsmentioning

confidence: 99%

Section: System Design and Constructionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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