title: In vivo detection of acinar microstructural changes in early emphysema with (3)He lung morphometry.
abstract: OBJECTIVE
  To quantitatively characterize early emphysematous changes in the lung microstructure of current and former smokers with noninvasive helium 3 ((3)He) lung morphometry and to compare these results with the clinical standards, pulmonary function testing (PFT) and low-dose computed tomography (CT).
  
  
  METHODS
  This study was approved by the local institutional review board, and all subjects provided informed consent. Thirty current and former smokers, each with a minimum 30-pack-year smoking history and mild or no abnormalities at PFT, underwent (3)He lung morphometry. This technique is based on diffusion MR imaging with hyperpolarized (3)He gas and yields quantitative localized in vivo measurements of acinar airway geometric parameters, such as airway radii, alveolar depth, and number of alveoli per unit lung volume. These measurements enable calculation of standard morphometric characteristics, such as mean linear intercept and surface-to-volume ratio.
  
  
  RESULTS
  Noninvasive (3)He lung morphometry was used to detect alterations in acinar structure in smokers with normal PFT findings. When compared with smokers with the largest forced expiratory volume in 1 second (FEV(1)) to forced vital capacity (FVC) ratio, those with chronic obstructive pulmonary disease had significantly reduced alveolar depth (0.07 mm vs 0.13 mm) and enlarged acinar ducts (0.36 mm vs 0.3 mm). The mean alveolar geometry measurements in the healthiest subjects were in excellent quantitative agreement with literature values obtained by using invasive techniques (acinar duct radius, 0.3 mm; alveolar depth, 0.14 mm at 1 L above functional residual capacity). (3)He lung morphometry depicted greater abnormalities than did PFT and CT. No adverse events were associated with inhalation of (3)He gas.
  
  
  CONCLUSIONS
  (3)He lung morphometry yields valuable noninvasive insight into early emphysematous changes in alveolar geometry with increased sensitivity compared with conventional techniques.
authors: Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4525 Scott Ave, Campus Box 8227, St Louis, MO 63110, USA. jdquirk@wustl.edu
authors: James D
authors: JD
authors: Quirk
authors: Barbara A
authors: BA
authors: Lutey
authors: David S
authors: DS
authors: Gierada
authors: Jason C
authors: JC
authors: Woods
authors: Robert M
authors: RM
authors: Senior
authors: Stephen S
authors: SS
authors: Lefrak
authors: Alexander L
authors: AL
authors: Sukstanskii
authors: Mark S
authors: MS
authors: Conradi
authors: Dmitriy A
authors: DA
authors: Yablonskiy
mesh_terms: D003287:Contrast Media; D005260:Female; D006371:Helium; D006801:Humans; D007554:Isotopes; D008168:Lung / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000473:pathology*; D019275:Radiopharmaceuticals
chemical_list: D003287:Contrast Media; D007554:Isotopes; D019275:Radiopharmaceuticals; D006371:Helium