title: Reducing view-sharing using compressed sensing in time-resolved contrast-enhanced magnetic resonance angiography.
abstract: OBJECTIVE
  To study temporal and spatial blurring artifacts from k-space view-sharing in time-resolved MR angiography (MRA) and to propose a technique for reducing these artifacts.
  
  
  METHODS
  We acquired k-space data sets using a three-dimensional time-resolved MRA view-sharing sequence and retrospectively reformatted them into two reconstruction frameworks: full view-sharing via time-resolved imaging with stochastic trajectories (TWIST) and minimal k-space view-sharing and compressed sensing (CS-TWIST). The two imaging series differed in temporal footprint but not in temporal frame rate. The artifacts from view-sharing were compared qualitatively and quantitatively in nine patients in addition to a phantom experiment.
  
  
  RESULTS
  CS-TWIST was able to reduce the imaging temporal footprint by two- to three-fold compared with TWIST, and the overall subjective image quality of CS-TWIST was higher than that for TWIST (P < 0.05). View sharing caused a delay in the visualization of small blood vessels, and the mean transit time of the carotid artery calculated based on TWIST reconstruction was 0.6 s longer than that for CS-TWIST (P < 0.01). In thoracic MRA, the shorter temporal footprint decreased the sensitivity to physiological motion blurring, and vessel sharpness was improved by 8.8% ± 6.0% using CS-TWIST (P < 0.05).
  
  
  CONCLUSIONS
  In time-resolved MRA, the longer temporal footprint due to view-sharing causes spatial and temporal artifacts. CS-TWIST is a promising method for reducing these artifacts.
authors.affiliation: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Stanislas
authors.initials: S
authors.lastname: Rapacchi
authors.affiliation: Siemens Healthcare, Los Angeles, California, USA.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Natsuaki
authors.affiliation: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Plotnik
authors.affiliation: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Simon
authors.initials: S
authors.lastname: Gabriel
authors.affiliation: Siemens Healthcare, Los Angeles, California, USA.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Laub
authors.affiliation: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
authors.affiliation: Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Hu
mesh_terms: D000465:Algorithms; D016477:Artifacts; D044962:Data Compression / Q000379:methods*; 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*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D062211:Spatio-Temporal Analysis