title: Comparison and Combination of Dual-Energy- and Iterative-Based Metal Artefact Reduction on Hip Prosthesis and Dental Implants.
abstract: OBJECTIVE
  To compare and combine dual-energy based and iterative metal artefact reduction on hip prosthesis and dental implants in CT.
  
  
  METHODS
  A total of 46 patients (women:50%,mean age:63±15years) with dental implants or hip prostheses (n = 30/20) were included and examined with a second-generation Dual Source Scanner. 120kV equivalent mixed-images were derived from reconstructions of the 100/Sn140kV source images using no metal artefact reduction (NOMAR) and iterative metal artefact reduction (IMAR). We then generated monoenergetic extrapolations at 130keV from source images without IMAR (DEMAR) or from source images with IMAR, (IMAR+DEMAR). The degree of metal artefact was quantified for NOMAR, IMAR, DEMAR and IMAR+DEMAR using a Fourier-based method and subjectively rated on a five point Likert scale by two independent readers.
  
  
  RESULTS
  In subjects with hip prosthesis, DEMAR and IMAR resulted in significantly reduced artefacts compared to standard reconstructions (33% vs. 56%; for DEMAR and IMAR; respectively, p<0.005), but the degree of artefact reduction was significantly higher for IMAR (all p<0.005). In contrast, in subjects with dental implants only IMAR showed a significant reduction of artefacts whereas DEMAR did not (71%, vs. 8% p<0.01 and p = 0.1; respectively). Furthermore, the combination of IMAR with DEMAR resulted in additionally reduced artefacts (Hip prosthesis: 47%, dental implants 18%; both p<0.0001).
  
  
  CONCLUSIONS
  IMAR allows for significantly higher reduction of metal artefacts caused by hip prostheses and dental implants, compared to a dual energy based method. The combination of DE-source images with IMAR and subsequent monoenergetic extrapolation provides an incremental benefit compared to both single methods.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Malte N
authors.initials: MN
authors.lastname: Bongers
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schabel
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Düsseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.affiliation: Siemens AG, Healthcare Sector, Siemensstraße 1, 91301, Forchheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Raupach
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015921:Dental Implants; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed
chemical_list: D015921:Dental Implants