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Publications [#132817] of G. Allan Johnson

Papers Published

  1. HE Möller, XJ Chen, MS Chawla, B Driehuys, LW Hedlund, GA Johnson, Signal dynamics in magnetic resonance imaging of the lung with hyperpolarized noble gases., Journal of magnetic resonance (San Diego, Calif. : 1997), UNITED STATES, vol. 135 no. 1 (November, 1998), pp. 133-43, ISSN 1090-7807
    (last updated on 2005/08/03)

    Abstract:
    The nonequilibrium bulk magnetic moment of hyperpolarized (HP) noble gases generated by optical pumping has unique characteristics. Based on the Bloch equations, a model was developed describing the signal dynamics of HP gases used in magnetic resonance imaging (MRI) of the lung with special consideration to the breathing cycle. Experimental verification included extensive investigations with HP 3He and 129Xe during both inspiration and held breath in live guinea pigs. Radial acquisition was used to investigate the view variations with a temporal resolution of 5 ms. Agreement between theoretical predictions and in vivo results was excellent. Additionally, information about effects from noble gas diffusion and spin-lattice relaxation was obtained. In vivo results for T1 were 28.8 +/- 1.8 s for 3He and 31.3 +/- 1.8 s for 129Xe. Comparison with in vitro data indicated that relaxation in the pulmonary gas space is dominated by dipolar coupling with molecular oxygen. The results provide a quantitative basis for optimizing pulse sequence design in HP gas MRI of the lung.

    Keywords:
    Animals • Guinea Pigs • Image Enhancement* • Lung • Magnetic Resonance Imaging* • Magnetics • Models, Theoretical • Noble Gases • Reproducibility of Results • anatomy & histology* • diagnostic use* • methods


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