title: Hyperpolarized 3He apparent diffusion coefficient MRI of the lung: reproducibility and volume dependency in healthy volunteers and patients with emphysema.
abstract: OBJECTIVE
  To measure the apparent diffusion coefficient (ADC) of hyperpolarized (HP) (3)He gas using diffusion weighted MRI in healthy volunteers and patients with emphysema and examine the reproducibility and volume dependency.
  
  
  METHODS
  A total of eight healthy volunteers and 16 patients with emphysema were examined after inhalation of HP (3)He gas mixed with nitrogen (N(2)) during breathhold starting from functional residual capacity (FRC) in supine position. Coronal diffusion-sensitized MR images were acquired. Each subject was imaged on three separate days over a seven-day period and received two different volumes (6% and 15% of total lung capacity [TLC]) of HP (3)He each day. ADC maps and histograms were calculated. The mean and standard deviation (SD) of the ADC at different days and volumes were compared.
  
  
  RESULTS
  The reproducibility of the mean ADC and SD over several days was good in both healthy volunteers and patients (SD range of 0.003-0.013 cm(2)/second and 0.001-0.009 cm(2)/second at 6% and 15% of TLC for healthy volunteers, and a SD range of 0.001-0.041 cm(2)/second and 0.001-0.011 cm(2)/second, respectively, for patients). A minor but significant increase in mean ADC with increased inhaled gas volume was observed in both groups.
  
  
  CONCLUSIONS
  Mean ADC and SD of HP (3)He MRI is reproducible and discriminates well between healthy controls and patients with emphysema at the higher gas volume. This method is robust and may be useful to gain new insights into the pathophysiology and course of emphysema.
authors.affiliation: Department of Radiology, Malmö University Hospital, Malmö, Sweden. Sandra.diaz@med.lu.se
authors.forename: Sandra
authors.initials: S
authors.lastname: Diaz
authors.forename: Ingrid
authors.initials: I
authors.lastname: Casselbrant
authors.forename: Eeva
authors.initials: E
authors.lastname: Piitulainen
authors.forename: Goran
authors.initials: G
authors.lastname: Pettersson
authors.forename: Peter
authors.initials: P
authors.lastname: Magnusson
authors.forename: Barry
authors.initials: B
authors.lastname: Peterson
authors.forename: Per
authors.initials: P
authors.lastname: Wollmer
authors.forename: Peter
authors.initials: P
authors.lastname: Leander
authors.forename: Olle
authors.initials: O
authors.lastname: Ekberg
authors.forename: Per
authors.initials: P
authors.lastname: Akeson
mesh_terms: D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005541:Forced Expiratory Volume; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D007554:Isotopes; D008168:Lung / Q000033:anatomy & histology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000503:physiopathology*; D015203:Reproducibility of Results; D014797:Vital Capacity
chemical_list: D007554:Isotopes; D006371:Helium