title: Metal artefact reduction in CT imaging of hip prostheses—an evaluation of commercial techniques provided by four vendors.
abstract: OBJECTIVE
  The aim of this study was to evaluate commercial metal artefact reduction (MAR) techniques in X-ray CT imaging of hip prostheses.
  
  
  METHODS
  Monoenergetic reconstructions of dual-energy CT (DECT) data and several different MAR algorithms, combined with single-energy CT or DECT, were evaluated by imaging a bilateral hip prosthesis phantom. The MAR images were compared with uncorrected images based on CT number accuracy and noise in different regions of interest.
  
  
  RESULTS
  The three MAR algorithms studied implied a general noise reduction (up to 67%, 74% and 77%) and an improvement in CT number accuracy, both in regions close to the prostheses and between the two prostheses. The application of monoenergetic reconstruction, without any MAR algorithm, did not decrease the noise in the regions close to the prostheses to the same extent as did the MAR algorithms and even increased the noise in the region between the prostheses.
  
  
  CONCLUSIONS
  The MAR algorithms evaluated generally improved CT number accuracy and substantially reduced the noise in the hip prostheses phantom images, both close to the prostheses and between the two prostheses. The study showed that the monoenergetic reconstructions evaluated did not sufficiently reduce the severe metal artefact caused by large orthopaedic implants.
  
  
  CONCLUSIONS
  This study evaluates several commercially available MAR techniques in CT imaging of large orthopaedic implants.
authors.affiliation: 1 Department of Medical Physics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: K M
authors.initials: KM
authors.lastname: Andersson
authors.affiliation: 2 Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Nowik
authors.affiliation: 1 Department of Medical Physics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Persliden
authors.affiliation: 1 Department of Medical Physics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.|3 School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Thunberg
authors.affiliation: 1 Department of Medical Physics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Norrman
mesh_terms: D000465:Algorithms; D000818:Animals; D016477:Artifacts; D002417:Cattle; D002857:Chromium; D003035:Cobalt; D006622:Hip Prosthesis; D019047:Phantoms, Imaging; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D002857:Chromium; D003035:Cobalt