title: An evaluation of pulmonary atelectasis and its re-expansion: hyperpolarized 3He MRI in the Yorkshire pig.
abstract: OBJECTIVE
  Atelectasis, the collapse of small airways, is a significant clinical problem. We use hyperpolarized (HP) 3He magnetic resonance imaging (MRI), or HP 3He MRI, to describe atelectasis in the normal Yorkshire pig, the pig with atelectasis, and the pig with re-expansion of atelectasis. We compare HP 3He MRI findings with depictions of atelectasis by proton MRI.
  
  
  METHODS
  During end-expiration in the anesthetized and paralyzed Yorkshire pig (n = 6), HP 3He gas produced by the optical pumping spin-exchange method, was delivered via an endotracheal tube. For two separate groups, atelectasis was either induced by Fogarty-catheter occlusion balloon inflation (n = 3), or lateral chest wall administration of sodium hydroxide (NaOH) (n = 3). MRI was performed at time zero, at 5, 9, 13, 15, and 19 minutes after atelectasis production, 30 minutes after balloon deflation, and 10 and 30 minutes after recruitment of atelectatic areas with increased tidal volumes and added positive end-expiratory pressure. High-resolution, cross-sectional MR images were procured, and comparison was made with the traditional proton MRI.
  
  
  RESULTS
  Atelectatic areas by HP 3He MRI were easily distinguishable in both subject groups, and correlated with those located by proton MR. HP 3He MR images showed absence of ventilation, whereas proton MR images depicted dense, white areas. Re-expansion of atelectasis was well delineated by HP 3He MRI.
  
  
  CONCLUSIONS
  HP 3He MRI may overcome many of the shortcomings of other well-established radiographic methods. HP 3He MRI is a novel, informative method for describing atelectasis and its re-expansion.
authors: Harbor/UCLA Medical Center, David Geffen School of Medicine at UCLA, Department of Anesthesiology, 1000 West Carson Blvd, Torrance, CA 90502, USA.
authors: Margaret A
authors: MA
authors: Ferrante
authors: Ali
authors: A
authors: Asiaii
authors: Masaru
authors: M
authors: Ishii
authors: David A
authors: DA
authors: Roberts
authors: Johan M
authors: JM
authors: Edvinsson
authors: Aman
authors: A
authors: Jalali
authors: Zebulon Z
authors: ZZ
authors: Spector
authors: Fabian
authors: F
authors: Meisel
authors: Rahim R
authors: RR
authors: Rizi
mesh_terms: D000818:Animals; D006371:Helium; D007554:Isotopes; D008279:Magnetic Resonance Imaging; D001261:Pulmonary Atelectasis / Q000175:diagnosis* / Q000503:physiopathology*; D013552:Swine
chemical_list: D007554:Isotopes; D006371:Helium