title: Comparison of hyperpolarized (3)He MRI with Xe-enhanced computed tomography imaging for ventilation mapping of rat lung.
abstract: Lung ventilation was mapped in five healthy Brown Norway rats (210-377 g) using both hyperpolarized (3)He MRI and Xe-enhanced computed tomography (Xe-CT) under similar ventilator conditions. Whole-lung measurements of ventilation r obtained with (3)He MRI were not significantly different from those obtained from Xe-CT (p = 0.1875 by Wilcoxon matched pairs test). The ventilation parameter r is defined as the fraction of refreshed gas per unit volume per breath. Regional ventilation was also measured in four regions of the lung using both methods. A two-tailed paired t-test was performed for each region, yielding p > 0.05 for all but the upper portion of the right lung. The distribution of regional ventilation was evaluated by calculating ventilation gradients in the superior/inferior (S/I) direction. The average S/I gradient obtained using the (3)He MRI method was found to be 0.17 ± 0.04 cm(-1) , whereas the average S/I gradient obtained using the Xe-CT method was found to be 0.016 ± 0.005 cm(-1) . In general, S/I ventilation gradients obtained from both methods were significantly different from each other (p = 0.0019 by two-tailed paired t-test). These regional differences in ventilation measurements may be caused by the manner in which the gas contrast agents distribute physiologically and/or by the imaging modality.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada. gsantyr@imaging.robarts.ca
authors.forename: Giles E
authors.initials: GE
authors.lastname: Santyr
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Couch
authors.forename: Wilfred W
authors.initials: WW
authors.lastname: Lam
authors.forename: Alexei
authors.initials: A
authors.lastname: Ouriadov
authors.forename: Maria
authors.initials: M
authors.lastname: Drangova
authors.forename: David G
authors.initials: DG
authors.lastname: McCormack
authors.forename: David W
authors.initials: DW
authors.lastname: Holdsworth
mesh_terms: D000818:Animals; D006371:Helium / Q000378:metabolism*; D007554:Isotopes; D008168:Lung / Q000000981:diagnostic imaging* / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology*; D051381:Rats; D011914:Rats, Inbred BN; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014978:Xenon / Q000378:metabolism*
chemical_list: D007554:Isotopes; D006371:Helium; D014978:Xenon