title: Analysis of intrapulmonary O(2) concentration by MR imaging of inhaled hyperpolarized helium-3.
abstract: Inhalation of hyperpolarized (3)He allows magnetic resonance imaging (MRI) of ventilated airspaces. (3)He hyperpolarization decays more rapidly when interacting with paramagnetic O(2). We describe a method for in vivo determination of intrapulmonary O(2) concentrations ([O(2)]) based on MRI analysis of the fate of measured amounts of inhaled hyperpolarized (3)He in imaged regions of the lung. Anesthetized pigs underwent controlled normoventilation in a 1.5-T MRI unit. The inspired O(2) fraction was varied to achieve different end-tidal [O(2)] fractions (FET(O(2))). With the use of a specifically designed applicator, (3)He (100 ml, 35-45% polarized) was administered at a predefined time within single tidal volumes. During subsequent inspiratory apnea, serial two-dimensional images of airways and lungs were acquired. At least once in each animal studied, the radio-frequency excitation used for imaging was doubled at constant FET(O(2)). Signal intensity measurements in regions of interest of the animals' lungs (volume range, 54-294 cm(3)), taken at two different radio-frequency excitations, permitted calculation of [O(2)] in these regions of interest. The [O(2)] fractions in the regions of interest correlated closely with FET(O(2)) (R = 0.879; P < 0.0001). O(2)-sensitive (3)He-MRI may allow noninvasive study of regional distribution of ventilation and alveolar PO(2) in the lung.
authors.affiliation: Department of Anesthesiology, Johannes Gutenberg University, D-55131 Mainz, Germany. eberle@anaesthesie.klinik.uni-mainz.de
authors.forename: B
authors.initials: B
authors.lastname: Eberle
authors.forename: N
authors.initials: N
authors.lastname: Weiler
authors.forename: K
authors.initials: K
authors.lastname: Markstaller
authors.forename: H
authors.initials: H
authors.lastname: Kauczor
authors.forename: A
authors.initials: A
authors.lastname: Deninger
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: L O
authors.initials: LO
authors.lastname: Lauer
authors.forename: T P
authors.initials: TP
authors.lastname: Roberts
authors.forename: W G
authors.initials: WG
authors.lastname: Schreiber
authors.forename: R
authors.initials: R
authors.lastname: Surkau
authors.forename: W F
authors.initials: WF
authors.lastname: Dick
authors.forename: E W
authors.initials: EW
authors.lastname: Otten
authors.forename: M
authors.initials: M
authors.lastname: Thelen
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D005240:Feasibility Studies; D006371:Helium / Q000008:administration & dosage; D007554:Isotopes; D008168:Lung / Q000033:anatomy & histology* / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D009994:Osmolar Concentration; D010100:Oxygen; D012119:Respiration; D013552:Swine; D013990:Tidal Volume
chemical_list: D007554:Isotopes; D006371:Helium; D010100:Oxygen