title: Single-breath xenon polarization transfer contrast (SB-XTC): implementation and initial results in healthy humans.
abstract: OBJECTIVE
  To implement and characterize a single-breath xenon transfer contrast (SB-XTC) method to assess the fractional diffusive gas transport F in the lung: to study the dependence of F and its uniformity as a function of lung volume; to estimate local alveolar surface area per unit gas volume S(A)/V(Gas) from multiple diffusion time measurements of F; to evaluate the reproducibility of the measurements and the necessity of B(1) correction in cases of centric and sequential encoding.
  
  
  METHODS
  In SB-XTC three or four gradient echo images separated by inversion/saturation pulses were collected during a breath-hold in eight healthy volunteers, allowing the mapping of F (thus S(A)/V(Gas)) and correction for other contributions such as T(1) relaxation, RF depletion and B(1) inhomogeneity from inherently registered data.
  
  
  RESULTS
  Regional values of F and its distribution were obtained; both the mean value and heterogeneity of F increased with the decrease of lung volume. Higher values of F in the bases of the lungs in supine position were observed at lower volumes in all volunteers. Local S(A)/V(Gas) (with a mean ± standard deviation of S(A)/V(Gas) = 89 ± 30 cm(-1)) was estimated in vivo near functional residual capacity. Calibration of SB-XTC on phantoms highlighted the necessity for B(1) corrections when k-space is traversed sequentially; with centric ordering B(1) distribution correction is dispensable.
  
  
  CONCLUSIONS
  The SB-XTC technique is implemented and validated for in vivo measurements of local S(A)/V(Gas).
authors.affiliation: Center for Pulmonary Functional Imaging, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. muradian@bwh.harvard.edu
authors.forename: Iga
authors.initials: I
authors.lastname: Muradyan
authors.forename: James P
authors.initials: JP
authors.lastname: Butler
authors.forename: Mikayel
authors.initials: M
authors.lastname: Dabaghyan
authors.forename: Mirko
authors.initials: M
authors.lastname: Hrovat
authors.forename: Isabel
authors.initials: I
authors.lastname: Dregely
authors.forename: Iulian
authors.initials: I
authors.lastname: Ruset
authors.forename: George P
authors.initials: GP
authors.lastname: Topulos
authors.forename: Eric
authors.initials: E
authors.lastname: Frederick
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatabu
authors.forename: William F
authors.initials: WF
authors.lastname: Hersman
authors.forename: Samuel
authors.initials: S
authors.lastname: Patz
mesh_terms: D000328:Adult; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000033:anatomy & histology* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014978:Xenon / Q000493:pharmacokinetics*
chemical_list: D003287:Contrast Media; D014978:Xenon