title: Exercise-induced bronchoconstriction: reproducibility of hyperpolarized 3He MR imaging.
abstract: OBJECTIVE
  To quantitatively evaluate interday, interreader, and intersite agreement of readers of hyperpolarized helium 3 (HPHe) MR images in patients with exercise-induced bronchoconstriction.
  
  
  METHODS
  This HIPAA-compliant, institutional review board approved study included 13 patients with exercise-induced bronchoconstriction. On two separate days, HPHe MR imaging of the lungs was performed at baseline, immediately after a 10-minute exercise challenge (postchallenge), and 45 minutes after exercise (recovery). Patients were imaged at two sites, six at site A and seven at site B. Images were analyzed independently by multiple readers at each site. Lung volume, ventilation defect volume, ventilated volume, and the number of defects were measured quantitatively, and the location of defects was evaluated qualitatively at site A. Interday and interreader agreement were evaluated by using the intraclass correlation coefficient (ICC), and intersite agreement was evaluated by using a modified Bland-Altman analysis.
  
  
  RESULTS
  The ICC between days for ventilation defect volume, ventilated volume, and number of defects was at least 0.74 at both sites. The ICC for lung volume was greater at site B (0.83-0.86) than at site A (0.60-0.65). Defects seen in the same location in the lung on both days included 19.7% of those seen on baseline images and 29.2% and 18.6% of defects on postchallenge and recovery images, respectively. Interreader ICC for each measurement was at least 0.82 for each site. Analysis of intersite agreement showed biases of 612 mL for lung volume, -60.7 mL for ventilation defect volume, 2.91% for ventilated volume, and -6.56 for number of defects.
  
  
  CONCLUSIONS
  The reported measures of reproducibility of HPHe MR imaging may help in the design and interpretation of single- and multicenter studies of patients with exercise-induced bronchoconstriction.
authors.affiliation: Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin, 1111 Highland Ave, Room 1005, Madison, WI 53705-2275, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Niles
authors.forename: Stanley J
authors.initials: SJ
authors.lastname: Kruger
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Dardzinski
authors.forename: Amy
authors.initials: A
authors.lastname: Harman
authors.forename: Nizar N
authors.initials: NN
authors.lastname: Jarjour
authors.forename: Marcella
authors.initials: M
authors.lastname: Ruddy
authors.forename: Scott K
authors.initials: SK
authors.lastname: Nagle
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: François
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D001982:Bronchial Diseases / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology*; D003251:Constriction, Pathologic; D015444:Exercise; D005260:Female; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results
chemical_list: D006371:Helium