title: Diffusion-weighted MRI of the lung with hyperpolarized helium-3: a study of reproducibility.
abstract: OBJECTIVE
  To determine the reproducibility of several parameters of the ADC measurement by calculating the scan-to-scan intrasubject variability.
  
  
  METHODS
  Measurements were performed using a gradient-echo sequence with a bipolar gradient for diffusion weighting (b=3.89 sec/cm2). Five patients with pulmonary emphysema, and six healthy-lung volunteers were included in the study. Images were acquired after inspiration of 3He during a single inspiratory breath-hold. To assess the reproducibility, the measurement was performed twice (time between measurements=20 minutes) without repositioning the subjects. Analysis was performed on the basis of region-of-interest (ROI) analysis and global lung ADC histograms.
  
  
  RESULTS
  The mean ADC of a ROI varied by 5.1% between two measurements for volunteers and by 6.1% for patients. In the global evaluation, the 75th percentile demonstrated the best reproducibility (2%), while other parameters showed variations up to 12%. Only the variation of the standard deviation (SD) and the measure of homogeneity of the ADC map showed a significant difference between patients and volunteers.
  
  
  CONCLUSIONS
  Diffusion-weighted imaging (DWI) is a well-reproducible method for assessing the lung microstructure.
authors.affiliation: Department of Radiology, Johannes Gutenberg University Medical School, Mainz, Germany.
authors.forename: Andreas E
authors.initials: AE
authors.lastname: Morbach
authors.forename: Klaus K
authors.initials: KK
authors.lastname: Gast
authors.forename: Jörg
authors.initials: J
authors.lastname: Schmiedeskamp
authors.forename: Anja
authors.initials: A
authors.lastname: Dahmen
authors.forename: Annette
authors.initials: A
authors.lastname: Herweling
authors.forename: Claus P
authors.initials: CP
authors.lastname: Heussel
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Schreiber
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000473:pathology*; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric
chemical_list: D006371:Helium