title: Three-dimensional pulmonary perfusion MRI with radial ultrashort echo time and spatial-temporal constrained reconstruction.
abstract: OBJECTIVE
  To assess the feasibility of spatial-temporal constrained reconstruction for accelerated regional lung perfusion using highly undersampled dynamic contrast-enhanced (DCE) three-dimensional (3D) radial MRI with ultrashort echo time (UTE).
  
  
  METHODS
  A combined strategy was used to accelerate DCE MRI for 3D pulmonary perfusion with whole lung coverage. A highly undersampled 3D radial UTE MRI acquisition was combined with an iterative constrained reconstruction exploiting principal component analysis and wavelet soft-thresholding for dimensionality reduction in space and time. The performance of the method was evaluated using a 3D fractal-based DCE digital lung phantom. Simulated perfusion maps and contrast enhancement curves were compared with ground truth using the structural similarity index (SSIM) to determine robust threshold and regularization levels. Feasibility studies were then performed in a canine and a human subject with 3D radial UTE (TE=0.08 ms) acquisition to assess feasibility of mapping regional 3D perfusion.
  
  
  RESULTS
  The method was able to accurately recover perfusion maps in the phantom with a nominal isotropic spatial resolution of 1.5 mm (SSIM of 0.949). The canine and human subject studies demonstrated feasibility for providing artifact-free perfusion maps in a simple 3D breath-held acquisition.
  
  
  CONCLUSIONS
  The proposed method is promising for fast and flexible 3D pulmonary perfusion imaging. Magn Reson
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bauman
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Johnson
authors.forename: Laura C
authors.initials: LC
authors.lastname: Bell
authors.forename: Julia V
authors.initials: JV
authors.lastname: Velikina
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Samsonov
authors.forename: Scott K
authors.initials: SK
authors.lastname: Nagle
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
mesh_terms: D000465:Algorithms; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001810:Blood Volume / Q000502:physiology*; D004285:Dogs; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008168:Lung / Q000098:blood supply / Q000502:physiology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D011652:Pulmonary Circulation / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D062211:Spatio-Temporal Analysis
keywords: MRI; UTE; compressed sensing; image reconstruction; lung perfusion; principal component analysis; radial; wavelets