title: Evaluation of structure-function relationships in asthma using multidetector CT and hyperpolarized He-3 MRI.
abstract: OBJECTIVE
  Although multiple detector computed tomography (MDCT) and hyperpolarized gas magnetic resonance imaging (HP MRI) have demonstrated ability to detect structural and ventilation abnormalities in asthma, few studies have sought to exploit or cross-validate the regional information provided by these techniques. The purpose of this work is to assess regional disease in asthma by evaluating the association of sites of ventilation defect on HP MRI with other regional markers of airway disease, including air trapping on MDCT and inflammatory markers on bronchoscopy.
  
  
  METHODS
  Both HP MRI using helium-3 and MDCT were acquired in the same patients. Supervised segmentation of the lung lobes on MRI and MDCT facilitated regional comparisons of ventilation abnormalities in the lung parenchyma. The percentage of spatial overlap was evaluated between regions of ventilation defect on HP MRI and hyperlucency on MDCT to determine associations between obstruction and likely regions of gas trapping. Similarly, lung lobes with high defect volume were compared to lobes with low defect volume for differences in inflammatory cell number and percentage using bronchoscopic assessment.
  
  
  RESULTS
  There was significant overlap between sites of ventilation defect on HP MRI and hyperlucency on MDCT suggesting that sites of airway obstruction and air trapping are associated in asthma. The percent (r=0.68; P= .0039) and absolute (r=0.61; P= .0125) number of neutrophils on bronchoalveolar lavage for the sampled lung lobe also directly correlated with increased defect volume.
  
  
  CONCLUSIONS
  These results show promise for using image guidance to assess specific regions of ventilation defect or air trapping in heterogeneous obstructive lung diseases such as asthma.
authors.affiliation: Department of Medical Physics, University of Wisconsin, Madison, WI 53792, USA. sfain@wisc.edu
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
authors.forename: Guillermo
authors.initials: G
authors.lastname: Gonzalez-Fernandez
authors.forename: Eric T
authors.initials: ET
authors.lastname: Peterson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Evans
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Sorkness
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Jarjour
authors.forename: William W
authors.initials: WW
authors.lastname: Busse
authors.forename: Janet E
authors.initials: JE
authors.lastname: Kuhlman
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D001999:Bronchoscopy; D005260:Female; D006371:Helium; D006801:Humans; D007554:Isotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D007554:Isotopes; D006371:Helium