title: Emphysematous changes and normal variation in smokers and COPD patients using diffusion 3He MRI.
abstract: BACKGROUND
  This study aims to quantify global and regional changes of diffusive motion of 3He gas within the lung, as determined by hyperpolarized 3He MR apparent diffusion coefficient (ADC) measurement, in non-smokers, smokers and chronic obstructive pulmonary disease (COPD) patients.
  
  
  METHODS
  Age-matched groups of six healthy non-smokers, five healthy smokers and five patients with COPD. The experiments were performed with approval from the local Research Ethics Committee. Diffusion imaging was performed following hyperpolarized 3He gas inhalation, producing ADC maps. Mean and standard deviation of the ADCs were used to compare the subject groups and assess regional variations within individuals.
  
  
  RESULTS
  The intra-individual standard deviation of ADC in the healthy smokers was significantly larger than that of the non-smoking group (P < 0.02). Compared to the non-smoking group, COPD patients had significantly higher mean and standard deviation of ADC (P < 0.01). The mean ADC in the anterior half of the chest was systematically higher than in the posterior half in the healthy non-smoking subject group.
  
  
  CONCLUSIONS
  This study suggests that there are regional trends in the ADC values of healthy volunteers that may have implications for the clinical interpretation of ADC values. Less homogeneous ADC values have been detected in asymptomatic smokers, indicative of damage to the distal air spaces.
authors.affiliation: Unit of Academic Radiology, University of Sheffield, Floor C, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, UK. ajswifto@yahoo.com
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Swift
authors.forename: Jim M
authors.initials: JM
authors.lastname: Wild
authors.forename: Stan
authors.initials: S
authors.lastname: Fichele
authors.forename: Neil
authors.initials: N
authors.lastname: Woodhouse
authors.forename: Sally
authors.initials: S
authors.lastname: Fleming
authors.forename: Judith
authors.initials: J
authors.lastname: Waterhouse
authors.forename: Rod A
authors.initials: RA
authors.lastname: Lawson
authors.forename: Martyn N J
authors.initials: MN
authors.lastname: Paley
authors.forename: Edwin J R
authors.initials: EJ
authors.lastname: Van Beek
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006371:Helium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000473:pathology* / Q000503:physiopathology; D012907:Smoking / Q000009:adverse effects*; D018709:Statistics, Nonparametric
chemical_list: D006371:Helium