title: Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  During recent years, magnetic resonance imaging (MRI) using hyperpolarised (HP) 3He gas has emerged as a promising new method for the imaging of lung ventilation. However, systematic comparisons with nuclear medicine techniques have not yet been performed. The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers.
  
  
  METHODS
  HP 3He MRI, 81mKr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The three scans were scored visually as percentage of non-ventilated/diseased lung, and a computer-based objective measure of the ventilated volume in HP 3He MRI and 81mKr SPECT and an emphysema index in HRCT were calculated.
  
  
  RESULTS
  We found a good correlation between HP 3He MRI and 81mKr SPECT for both visual defect score (r=0.80, p<0.0001) and objective estimate of ventilation (r=0.45, p=0.0157). In addition, both scans were well correlated with reference methods for the diagnosis of emphysema (pulmonary function test and HRCT). The defect scores were largest on 81mKr SPECT (the score on HP 3He MRI was one-third less than that on 81mKr SPECT), but the difference was reduced after normalisation for different breathing depths (HP 3He MRI at total lung capacity; 81mKr SPECT at tidal breathing at functional residual capacity).
  
  
  CONCLUSIONS
  HP 3He MRI provides detailed ventilation distribution images and defect scores are comparable on HP 3He MRI and 81mKr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP 3He MRI. HP 3He MRI is a promising new diagnostic tool for the assessment of ventilation distribution.
authors.affiliation: Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Rigshospitalet, Denmark. stavngaard@dadlnet.dk
authors.forename: Trine
authors.initials: T
authors.lastname: Stavngaard
authors.forename: Lise Vejby
authors.initials: LV
authors.lastname: Søgaard
authors.forename: Jann
authors.initials: J
authors.lastname: Mortensen
authors.forename: Lars G
authors.initials: LG
authors.lastname: Hanson
authors.forename: Jörg
authors.initials: J
authors.lastname: Schmiedeskamp
authors.forename: Anne Kiil
authors.initials: AK
authors.lastname: Berthelsen
authors.forename: Asger
authors.initials: A
authors.lastname: Dirksen
mesh_terms: D000280:Administration, Inhalation; D003287:Contrast Media; D005260:Female; D006371:Helium / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D007727:Krypton Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D003287:Contrast Media; D007727:Krypton Radioisotopes; D019275:Radiopharmaceuticals; D006371:Helium