title: Highly undersampled contrast-enhanced MRA with iterative reconstruction: Integration in a clinical setting.
abstract: OBJECTIVE
  To integrate, optimize, and evaluate a three-dimensional (3D) contrast-enhanced sparse MRA technique with iterative reconstruction on a standard clinical MR system.
  
  
  METHODS
  Data were acquired using a highly undersampled Cartesian spiral phyllotaxis sampling pattern and reconstructed directly on the MR system with an iterative SENSE technique. Undersampling, regularization, and number of iterations of the reconstruction were optimized and validated based on phantom experiments and patient data. Sparse MRA of the whole head (field of view: 265 × 232 × 179 mm(3) ) was investigated in 10 patient examinations.
  
  
  RESULTS
  High-quality images with 30-fold undersampling, resulting in 0.7 mm isotropic resolution within 10 s acquisition, were obtained. After optimization of the regularization factor and of the number of iterations of the reconstruction, it was possible to reconstruct images with excellent quality within six minutes per 3D volume. Initial results of sparse contrast-enhanced MRA (CEMRA) in 10 patients demonstrated high-quality whole-head first-pass MRA for both the arterial and venous contrast phases.
  
  
  CONCLUSIONS
  While sparse MRI techniques have not yet reached clinical routine, this study demonstrates the technical feasibility of high-quality sparse CEMRA of the whole head in a clinical setting. Sparse CEMRA has the potential to become a viable alternative where conventional CEMRA is too slow or does not provide sufficient spatial resolution.
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Aurelien F
authors.initials: AF
authors.lastname: Stalder
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Germany.|High Field and Hybrid MR Imaging, University Hospital Essen, Germany.
authors.forename: Harald H
authors.initials: HH
authors.lastname: Quick
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schlamann
authors.affiliation: Erwin L. Hahn Institute for MR Imaging, University of Duisburg-Essen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Maderwald
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schmitt
authors.affiliation: Siemens Corporate Technology, Princeton, New Jersey, USA.
authors.forename: Qiu
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Siemens Corporate Technology, Princeton, New Jersey, USA.
authors.forename: Mariappan S
authors.initials: MS
authors.lastname: Nadar
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Zenge
mesh_terms: D000465:Algorithms; D002536:Cerebral Arteries / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D008536:Meglumine; D009942:Organometallic Compounds; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D018511:Systems Integration
chemical_list: D009942:Organometallic Compounds; C090600:gadobutrol; D008536:Meglumine; C072417:gadoterate meglumine
keywords: contrast-enhanced MRA; intracranial MRA; iterative reconstruction; sparse MRI; sparse data sampling