title: Anatomical distribution of 3He apparent diffusion coefficients in severe chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To evaluate the anatomical distribution of apparent diffusion coefficients (ADC) using hyperpolarized helium-3 (3He) MRI in chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  Hyperpolarized 3He MRI was performed in eight healthy and seven COPD subjects under breathhold conditions in the supine position to determine ADC values from diffusion-weighted images and evaluate anterior-posterior (AP) and superior-inferior (SI) differences.
  
  
  RESULTS
  ADC differences between anterior and posterior slices, DeltaAP, was 0.06 +/-0.01 cm2/second for healthy volunteers and 0.04 +/-0.02 cm2/second for COPD subjects and was significant for each subject (P < 0.01). The AP ADC gradient was -3.98 x 10(-3) +/-0.59 cm2/second/cm for healthy volunteers and -2.04 x 10(-3) +/-0.89 cm2/second/cm for COPD subjects. The difference in ADC between superior and inferior regions of interest (ROIs), DeltaSI, was 0.02 +/-0.02 cm2/second for healthy volunteers and 0.10 +/-0.09 cm2/second for COPD subjects, which was significant for each subject (P < 0.05). The SI ADC gradient was -0.63 x 10(-3) +/-2.23 cm2/second/cm for healthy volunteers and -6.61 x 10(-3) +/-6.68 cm2/second/cm for COPD subjects. DeltaAP, AP-gradient, and SI-gradient were significantly different between healthy volunteers and COPD subjects (P < 0.05).
  
  
  CONCLUSIONS
  In all subjects, ADC anatomical differences were significant and mean ADC was dependent on anatomic location and disease status.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Evans
authors.forename: David
authors.initials: D
authors.lastname: McCormack
authors.forename: Alexei
authors.initials: A
authors.lastname: Ouriadov
authors.forename: Roya
authors.initials: R
authors.lastname: Etemad-Rezai
authors.forename: Giles
authors.initials: G
authors.lastname: Santyr
authors.forename: Grace
authors.initials: G
authors.lastname: Parraga
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006371:Helium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007554:Isotopes; D008297:Male; D019047:Phantoms, Imaging; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism*; D012129:Respiratory Function Tests; D018709:Statistics, Nonparametric; D016683:Supine Position
chemical_list: D007554:Isotopes; D006371:Helium