title: Measurement of alveolar oxygen partial pressure in the rat lung using Carr-Purcell-Meiboom-Gill spin-spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT.
abstract: Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, (3) He and (129) Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin-spin relaxation rate (R(2) ) of (3) He at low magnetic field strengths (<0.1 T) in vivo. R(2) measurements can be achieved efficiently using the Carr-Purcell-Meiboom-Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr-Purcell-Meiboom-Gill R(2) values of hyperpolarized (3) He and (129) Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin-spin relaxivity constants for (3) He and (129) Xe were determined to be (5.2 ± 0.6) × 10(-6) Pa(-1) sec(-1) and (7.3 ± 0.4) × 10(-6) Pa(-1) s(-1) compared with spin-lattice relaxivity constants of (4.0 ± 0.4) × 10(-6) Pa(-1) s(-1) and (4.3 ± 1.3) × 10(-6) Pa(-1) s(-1), respectively. In vivo experimental measurements of alveolar oxygen partial pressure using (3) He in whole rat lung show good agreement (r(2) = 0.973) with predictions based on lung volumes and ventilation parameters. For (129) Xe, multicomponent relaxation was observed with one component exhibiting an increase in R(2) with decreasing alveolar oxygen partial pressure.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, London, Canada.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Kraayvanger
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Bidinosti
authors.forename: William
authors.initials: W
authors.lastname: Dominguez-Viqueira
authors.forename: Juan
authors.initials: J
authors.lastname: Parra-Robles
authors.forename: Matthew
authors.initials: M
authors.lastname: Fox
authors.forename: Wilfred W
authors.initials: WW
authors.lastname: Lam
authors.forename: Giles E
authors.initials: GE
authors.lastname: Santyr
mesh_terms: D000818:Animals; D006371:Helium; D007554:Isotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000378:metabolism*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley; D013113:Spin Labels; D014979:Xenon Isotopes
chemical_list: D007554:Isotopes; D019275:Radiopharmaceuticals; D013113:Spin Labels; D014979:Xenon Isotopes; D006371:Helium; D010100:Oxygen