title: Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC.
abstract: OBJECTIVE
  Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants.
  
  
  METHODS
  Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant.
  
  
  RESULTS
  There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were "adequate" to "good" on CS-SEMAC and "non-diagnostic" to "adequate" on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively).
  
  
  CONCLUSIONS
  Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC.
authors: Russell H. Morgan Department of Radiology and Radiological Science, Section of Musculoskeletal Radiology, Johns Hopkins University School of Medicine, 601 N Caroline Street, JHOC 3140A, Baltimore, MD, 21287, USA. jfritz9@jhmi.edu.
authors: Jan
authors: J
authors: Fritz
authors: Department of Radiology, University of Freiburg, Robert-Koch-Straße 3, 79106, Freiburg im Breisgau, Germany.
authors: Benjamin
authors: B
authors: Fritz
authors: Russell H. Morgan Department of Radiology and Radiological Science, Section of Musculoskeletal Radiology, Johns Hopkins University School of Medicine, 601 N Caroline Street, JHOC 3140A, Baltimore, MD, 21287, USA.
authors: Gaurav K
authors: GK
authors: Thawait
authors: Siemens Healthcare GmbH, Allee am Roethelheimpark 2, 91052, Erlangen, Germany.
authors: Esther
authors: E
authors: Raithel
authors: Siemens Healthcare USA, Inc., 600 N. Wolfe Street, Park 320, Baltimore, MD, 21287, USA.
authors: Wesley D
authors: WD
authors: Gilson
authors: Siemens Healthcare GmbH, Allee am Roethelheimpark 2, 91052, Erlangen, Germany.
authors: Mathias
authors: M
authors: Nittka
authors: Department of Orthopedic Surgery, Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Michael A
authors: MA
authors: Mont
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D016477:Artifacts; D044962:Data Compression / Q000379:methods*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio
keywords: Compressed sensing; Hip; MARS; MRI; Metal-on-metal; Resurfacing arthroplasty; SEMAC; Sparsity