title: Hyperpolarized Xenon-129 gas-exchange imaging of lung microstructure: first case studies in subjects with obstructive lung disease.
abstract: OBJECTIVE
  To develop and test a method to noninvasively assess the functional lung microstructure.
  
  
  METHODS
  The Multiple exchange time Xenon polarization Transfer Contrast technique (MXTC) encodes xenon gas-exchange contrast at multiple delay times permitting two lung-function parameters to be derived: (i) MXTC-F, the long exchange-time depolarization value, which is proportional to the tissue to alveolar-volume ratio and (ii) MXTC-S, the square root of the xenon exchange-time constant, which characterizes thickness and composition of alveolar septa. Three healthy volunteers, one asthmatic, and two chronic obstructive pulmonary disease (COPD) (GOLD stage I and II) subjects were imaged with MXTC MRI. In a subset of subjects, hyperpolarized xenon-129 ADC MRI and CT imaging were also performed.
  
  
  RESULTS
  The MXTC-S parameter was found to be elevated in subjects with lung disease (P-value = 0.018). In the MXTC-F parameter map it was feasible to identify regional loss of functional tissue in a COPD patient. MXTC-F maps showed excellent regional correlation with CT and ADC (P ≥ 0.90) in one COPD subject.
  
  
  CONCLUSIONS
  The functional tissue-density parameter MXTC-F showed regional agreement with other imaging techniques. The newly developed parameter MXTC-S, which characterizes the functional thickness of alveolar septa, has potential as a novel biomarker for regional parenchymal inflammation or thickening.
authors.affiliation: Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA. imu4@unh.edu
authors.forename: Isabel
authors.initials: I
authors.lastname: Dregely
authors.forename: John P
authors.initials: JP
authors.lastname: Mugler
authors.forename: Iulian C
authors.initials: IC
authors.lastname: Ruset
authors.forename: Talissa A
authors.initials: TA
authors.lastname: Altes
authors.forename: Jaime F
authors.initials: JF
authors.lastname: Mata
authors.forename: G Wilson
authors.initials: GW
authors.lastname: Miller
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Ketel
authors.forename: Steve
authors.initials: S
authors.lastname: Ketel
authors.forename: Jan
authors.initials: J
authors.lastname: Distelbrink
authors.forename: F W
authors.initials: FW
authors.lastname: Hersman
authors.forename: Kai
authors.initials: K
authors.lastname: Ruppert
mesh_terms: D000328:Adult; D000465:Algorithms; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000473:pathology*; D008173:Lung Diseases, Obstructive / Q000175:diagnosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008490:Medical Informatics / Q000379:methods; D008875:Middle Aged; D015233:Models, Statistical; D012984:Software; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D014978:Xenon; D014979:Xenon Isotopes / Q000737:chemistry*
chemical_list: D003287:Contrast Media; D014979:Xenon Isotopes; D014978:Xenon