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Christopher Deninger 《Inventiones Mathematicae》1991,104(1):245-261
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Deninger AJ Eberle B Ebert M Grossmann T Heil W Kauczor H Lauer L Markstaller K Otten E Schmiedeskamp J Schreiber W Surkau R Thelen M Weiler N 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,141(2):207-216
We present a new method to determine in vivo the temporal evolution of intrapulmonary oxygen concentrations by functional lung imaging with hyperpolarized (3)Helium ((3)He-->). Single-breath, single-bolus visualization of (3)He--> administered to the airspaces is used to analyze nuclear spin relaxation caused by the local oxygen partial pressure p(O(2))(t). We model the dynamics of hyperpolarization in the lung by rate equations. Based hereupon, a double acquisition technique is presented to separate depolarization by RF pulses and oxygen induced relaxation. It permits the determination of p(O(2)) with a high accuracy of up to 3% with simultaneous flip angle calibration using no additional input parameters. The time course of p(O(2)) during short periods of breathholding is found to be linear in a pig as well as in a human volunteer. We also measured the wall relaxation time in the lung and deduced a lower limit of 4.3 min. 相似文献
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A. J. Deninger B. Eberle M. Ebert T. Großmann W. Heil H. -U. Kauczor L. Lauer K. Markstaller E. Otten J. Schmiedeskamp W. Schreiber R. Surkau M. Thelen N. Weiler 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,141(2):207
We present a new method to determine in vivo the temporal evolution of intrapulmonary oxygen concentrations by functional lung imaging with hyperpolarized 3Helium (3
). Single-breath, single-bolus visualization of 3
administered to the airspaces is used to analyze nuclear spin relaxation caused by the local oxygen partial pressure pO2(t). We model the dynamics of hyperpolarization in the lung by rate equations. Based hereupon, a double acquisition technique is presented to separate depolarization by RF pulses and oxygen induced relaxation. It permits the determination of pO2 with a high accuracy of up to 3% with simultaneous flip angle calibration using no additional input parameters. The time course of pO2 during short periods of breathholding is found to be linear in a pig as well as in a human volunteer. We also measured the wall relaxation time in the lung and deduced a lower limit of 4.3 min. 相似文献
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Supported by Grant PB 85-0075 from CAICYT. 相似文献
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Ch. Deninger 《Journal of Pure and Applied Algebra》1988,50(3):231-235
We show that under certain additional hypotheses the proper base change theorem holds for arbitrary abelian sheaves. 相似文献