title: Sparse-SEMAC: rapid and improved SEMAC metal implant imaging using SPARSE-SENSE acceleration.
abstract: To develop an accelerated SEMAC metal implant MRI technique (Sparse-SEMAC) with reduced scan time and improved metal distortion correction.
  
  
  
  Sparse-SEMAC jointly exploits the inherent sparsity along the additional phase-encoding dimension and multicoil encoding capabilities to significantly accelerate data acquisition. A prototype pulse sequence with pseudorandom ky-kzundersampling and an inline image reconstruction was developed for integration in clinical studies. Three patients with hip implants were imaged using the proposed Sparse-SEMAC with eight-fold acceleration and compared with the standard-SEMAC technique used in clinical studies (three-fold GRAPPA acceleration). Measurements were performed with SEMAC-encoding steps (SES) = 15 for Sparse-SEMAC and SES = 9 for Standard-SEMAC using high spatial resolution Proton Density (PD) and lower-resolution STIR acquisitions. Two expert musculoskeletal (MSK) radiologists performed a consensus reading to score image-quality parameters.
  
  
  
  Sparse-SEMAC enables up to eight-fold acceleration of data acquisition that results in two-fold scan time reductions, compared with Standard-SEMAC, with improved metal artifact correction for patients with hip implants without degrading spatial resolution.
  
  
  
  The high acceleration enabled by Sparse-SEMAC would enable clinically feasible examination times with improved correction of metal distortion. Magn Reson Med 78:79-87, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, NYU School of Medicine, New York, New York, USA.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Otazo
authors.affiliation: Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Nittka
authors.affiliation: Department of Radiology, NYU School of Medicine, New York, New York, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Bruno
authors.affiliation: Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Esther
authors.initials: E
authors.lastname: Raithel
authors.affiliation: Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Geppert
authors.affiliation: Department of Radiology, NYU School of Medicine, New York, New York, USA.
authors.forename: Soterios
authors.initials: S
authors.lastname: Gyftopoulos
authors.affiliation: Department of Radiology, NYU School of Medicine, New York, New York, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Recht
authors.affiliation: Department of Radiology, NYU School of Medicine, New York, New York, USA.
authors.forename: Leon
authors.initials: L
authors.lastname: Rybak
mesh_terms: D000465:Algorithms; D016477:Artifacts; D002102:Cadaver; D044962:Data Compression / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008670:Metals; D015588:Observer Variation; D019736:Prostheses and Implants; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D008670:Metals
keywords: SPARSE-SENSE; iterative reconstruction; metal artifacts; metallic implants; parallel imaging