title: Changes in regional airflow obstruction over time in the lungs of patients with asthma: evaluation with 3He MR imaging.
abstract: OBJECTIVE
  To determine changes in regional airflow obstruction over time in the lungs of patients with asthma, as demonstrated with hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging, and to assess correlations with disease severity and use of asthma medications.
  
  
  METHODS
  Institutional review board approval and written informed consent were obtained for this HIPAA-compliant study. Use of (3)He was approved by the U.S. Food and Drug Administration. Forty-three patients underwent 103 MR imaging studies in total; 26 were imaged twice within 42-82 minutes (same day), and 17 were imaged on 3 days between 1 and 476 days (multiday). Each day, spirometry was performed, disease severity was determined, and the use of asthma medications was recorded. Images were reviewed in a pairwise fashion to determine total ventilation defect number, defects in same location between imaging studies, and size. Parametric and nonparametric statistical methods were used.
  
  
  RESULTS
  For the same-day examinations, the mean number of defects per image section was similar at baseline and repeat imaging (1.8 +/- 1.9 [standard deviation] vs 1.6 +/- 1.9, respectively; P = .15), with 75% of defects remaining in the same location and 71% of these not changing size. For the multiday examinations, the mean number of defects per section was higher for study 2 (2.4 +/- 1.5) than study 1 (1.7 +/- 0.9, P = .02), was lower for study 3 (1.5 +/- 1.1) than for study 2 (P < .01), and was similar for studies 1 and 3 (P = .56). Time between examinations was not associated with change in mean number of defects per section (median intrasubject correlation [r(m)] = 0.01, P = .64) or change in spirometric values (range of r(m) values: -0.56 to -0.31; range of P values: .09-.71). Defects in the same location decreased with time (r(m) = -0.83, P < .01), with 67% persisting between studies 1 and 2 (median interval, 31 days), 43% persisting between studies 2 and 3 (median interval, 41 days), and 38% persisting between studies 1 and 3 (median interval, 85 days); 46%-58% of defects remained unchanged in size. These trends were the same regardless of disease severity or medication use.
  
  
  CONCLUSIONS
  In asthma, focal airflow impediment within the lungs can be markedly persistent over time, regardless of disease severity or treatment.
authors.affiliation: Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA. delange@virginia.edu
authors.forename: Eduard E
authors.initials: EE
authors.lastname: de Lange
authors.forename: Talissa A
authors.initials: TA
authors.lastname: Altes
authors.forename: James T
authors.initials: JT
authors.lastname: Patrie
authors.forename: John J
authors.initials: JJ
authors.lastname: Battiston
authors.forename: Adam P
authors.initials: AP
authors.lastname: Juersivich
authors.forename: John P
authors.initials: JP
authors.lastname: Mugler
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Platts-Mills
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D006371:Helium; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012720:Severity of Illness Index; D013147:Spirometry; D018709:Statistics, Nonparametric
chemical_list: D006371:Helium