title: Quantification of regional intrapulmonary oxygen partial pressure evolution during apnea by (3)He MRI.
abstract: 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.
authors.affiliation: Department of Physics, University of Mainz, Mainz, D-55099, Germany.
authors.forename: A J
authors.initials: AJ
authors.lastname: Deninger
authors.forename: B
authors.initials: B
authors.lastname: Eberle
authors.forename: M
authors.initials: M
authors.lastname: Ebert
authors.forename: T
authors.initials: T
authors.lastname: Grossmann
authors.forename: W
authors.initials: W
authors.lastname: Heil
authors.forename: H
authors.initials: H
authors.lastname: Kauczor
authors.forename: L
authors.initials: L
authors.lastname: Lauer
authors.forename: K
authors.initials: K
authors.lastname: Markstaller
authors.forename: E
authors.initials: E
authors.lastname: Otten
authors.forename: J
authors.initials: J
authors.lastname: Schmiedeskamp
authors.forename: W
authors.initials: W
authors.lastname: Schreiber
authors.forename: R
authors.initials: R
authors.lastname: Surkau
authors.forename: M
authors.initials: M
authors.lastname: Thelen
authors.forename: N
authors.initials: N
authors.lastname: Weiler
mesh_terms: D000328:Adult; D000818:Animals; D001049:Apnea; D006371:Helium; D006801:Humans; D007554:Isotopes; D008168:Lung / Q000033:anatomy & histology / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000502:physiology*; D010313:Partial Pressure; D019047:Phantoms, Imaging; D013552:Swine
chemical_list: D007554:Isotopes; D006371:Helium; D010100:Oxygen