title: Assessment of the lung microstructure in patients with asthma using hyperpolarized 3He diffusion MRI at two time scales: comparison with healthy subjects and patients with COPD.
abstract: OBJECTIVE
  To investigate short- and long-time-scale (3)He diffusion in asthma.
  
  
  METHODS
  A hybrid MRI sequence was developed to obtain co-registered short- and long-time-scale apparent diffusion coefficient (ADC) maps during a single breath-hold. The study groups were: asthma (n = 14); healthy (n = 14); chronic obstructive pulmonary disease (COPD) (n = 9). Correlations were made between mean-ADC and %ADC-abn (abnormal) (%pixels with ADC > mean +2 SD of healthy) at both time scales and spirometry. Sensitivities were determined using receiver operating characteristic (ROC) analysis.
  
  
  RESULTS
  For asthmatics, the short- and long-time-scale group-mean ADCs were 0.254 +/- 0.032 cm(2)/s and 0.0237 +/- 0.0055 cm(2)/s, respectively, representing a 9% and 27% (P = 0.038 and P = 0.005) increase compared to the healthy group. The group-mean %ADC-abn were 6.4% +/- 3.7% and 17.5% +/- 14.2%, representing a 107% and 272% (P = 0.004 and P = 0.006) increase. For COPD much greater elevations were observed. %ADC-abn provided better discrimination than mean-ADC between asthmatic and healthy subjects. In asthmatics ADC did not correlate with spirometry.
  
  
  CONCLUSIONS
  With long-time scale (3)He diffusion magnetic resonance imaging (MRI) changes in lung microstructure were detected in asthma that more conspicuous regionally than at the short time scale. The hybrid diffusion method is a novel means of identifying small airway disease.
authors.affiliation: Department of Radiology, University of Virginia, Charlottesville, VA 22908, USA. chengbo@gmail.com
authors.forename: Chengbo
authors.initials: C
authors.lastname: Wang
authors.forename: Talissa A
authors.initials: TA
authors.lastname: Altes
authors.forename: John P
authors.initials: JP
authors.lastname: Mugler
authors.forename: G Wilson
authors.initials: GW
authors.lastname: Miller
authors.forename: Kai
authors.initials: K
authors.lastname: Ruppert
authors.forename: Jaime F
authors.initials: JF
authors.lastname: Mata
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Cates
authors.forename: Larry
authors.initials: L
authors.lastname: Borish
authors.forename: Eduard E
authors.initials: EE
authors.lastname: de Lange
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology*; D012680:Sensitivity and Specificity; D013147:Spirometry