title: Investigation of hyperpolarized 3He magnetic resonance imaging utility in examining human airway diameter behavior in asthma through comparison with high-resolution computed tomography.
abstract: OBJECTIVE
  Application of a previously developed model-based algorithm on hyperpolarized (HP) (3)He magnetic resonance (MR) dynamic projection images of phantoms was extended to investigate the utility of HP (3)He MR imaging (MRI) in quantifying airway caliber changes associated with asthma.
  
  
  METHODS
  Airways of seven volunteers were imaged and measured using HP (3)He MRI and multidetector-row computed tomography (MDCT) before and after a methacholine (MCh) challenge. MDCT data were obtained at functional residual capacity and 1 L above functional residual capacity.
  
  
  RESULTS
  Comparison of the resultant data showed that HP (3)He MRI did not match MDCT in measuring the ratios of airway calibers before and after the MCh challenge in 37% to 43% of the airways from the first six generations at the two lung volumes tested. However, MDCT did yield the observation that 49% to 69% of these airways displayed bronchodilation following MCh challenge.
  
  
  CONCLUSIONS
  The current implementation of HP (3)He MRI did not match the MCh-induced postchallenge-to-prechallenge airway caliber ratios as measured with MDCT. Elevated parenchymal tethering due to bronchoconstriction-induced hyperinflation was proposed as a possible explanation for this airway dilation.
authors.affiliation: Department of Radiology, Brigham & Women's Hospital, 221 Longwood Avenue, Boston, MA 02115, USA. magis91@yahoo.com
authors.forename: Yang-Sheng
authors.initials: YS
authors.lastname: Tzeng
authors.forename: Eric
authors.initials: E
authors.lastname: Hoffman
authors.forename: Janice
authors.initials: J
authors.lastname: Cook-Granroth
authors.forename: Jessica
authors.initials: J
authors.lastname: Gereige
authors.forename: Joey
authors.initials: J
authors.lastname: Mansour
authors.forename: George
authors.initials: G
authors.lastname: Washko
authors.forename: Michael
authors.initials: M
authors.lastname: Cho
authors.forename: Evan
authors.initials: E
authors.lastname: Stepp
authors.forename: Kenneth
authors.initials: K
authors.lastname: Lutchen
authors.forename: Mitchell
authors.initials: M
authors.lastname: Albert
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000465:Algorithms; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology; D005260:Female; D005652:Functional Residual Capacity; D006371:Helium; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007554:Isotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D012129:Respiratory Function Tests; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014132:Trachea / Q000503:physiopathology
chemical_list: D007554:Isotopes; D006371:Helium