title: Model-Based Iterative Reconstruction (MBIR) for the Reduction of Metal Artifacts on CT.
abstract: OBJECTIVE
  The purpose of this article is to study the added value of model-based iterative reconstruction (MBIR) on metal artifact reduction on CT compared with standard filtered back projection (FBP).
  
  
  METHODS
  Ex vivo imaging was performed on several metal implants. Datasets were reconstructed with standard FBP and MBIR algorithms. The sizes of the artifacts surrounding the metal implant were recorded and compared. In vivo imaging was performed on 62 patients with metal implants. Each dataset was reconstructed with FBP and MBIR algorithms. Objective image quality was assessed by measuring the size of the artifact generated by the metal implant. Subjective image quality was graded on a 3-point scale, taking into account the visibility of the bone-metal interface, as well as the visibility of the neighboring soft tissues.
  
  
  RESULTS
  Ex vivo analysis yielded a reduction of 82% in the size of the artifact when using the MBIR algorithm, compared with the FBP algorithm. The mean (SD) size of the artifacts was 1.4 ± 0.8 and 0.25 ± 0.06 cm(2) with FBP and MBIR, respectively. In vivo, the mean size of the artifacts decreased from 7.3 ± 1.5 cm(2) to 4.0 ± 0.9 cm(2) for FBP and MBIR, respectively (p = 0.012). The subjective image quality analysis showed an equal or better bone-metal interface of MBIR algorithm in 85% of cases. Visibility of the soft tissue surrounding the metal implant was determined to be equal or better in 97% of cases in which MBIR was used.
  
  
  CONCLUSIONS
  This study shows that the MBIR algorithm allows a clear reduction of metal artifacts on CT images and, hence, a better analysis of the soft tissue surrounding the metal implant compared with FBP.
authors.affiliation: 1 Department of Radiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1211 Genève 4, Switzerland.
authors.forename: Sana
authors.initials: S
authors.lastname: Boudabbous
authors.affiliation: 1 Department of Radiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1211 Genève 4, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Arditi
authors.affiliation: 1 Department of Radiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1211 Genève 4, Switzerland.
authors.forename: Emilie
authors.initials: E
authors.lastname: Paulin
authors.affiliation: 2 Department of Oncology, Geneva University Hospital, Genève, Switzerland.
authors.forename: Aphrodite
authors.initials: A
authors.lastname: Syrogiannopoulou
authors.affiliation: 1 Department of Radiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1211 Genève 4, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Becker
authors.affiliation: 1 Department of Radiology, Geneva University Hospital, rue Gabrielle-Perret-Gentil 4, 1211 Genève 4, Switzerland.
authors.forename: Xavier
authors.initials: X
authors.lastname: Montet
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D019736:Prostheses and Implants; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D008670:Metals
keywords: CT; metal artifact reduction; model-based iterative reconstruction