title: CT metal artefact reduction for internal fixation of the proximal humerus: value of mono-energetic extrapolation from dual-energy and iterative reconstructions.
abstract: OBJECTIVE
  To assess the value of dual-energy computed tomography (DECT) and an iterative frequency split-normalized metal artefact reduction (IFS-MAR) algorithm compared to filtered back projections (FBP) from single-energy CT (SECT) for artefact reduction in internally fixated humeral fractures.
  
  
  METHODS
  Six internally fixated cadaveric humeri were examined using SECT and DECT. Data were reconstructed using FBP, IFS-MAR, and mono-energetic DECT extrapolations. Image analysis included radiodensity values and qualitative evaluation of artefacts, image quality, and level of confidence for localizing screw tips.
  
  
  RESULTS
  Radiodensity values of streak artefacts were significantly different (p < 0.05) between FBP (-104 ± 222) and IFS-MAR (73 ± 122), and between FBP and DECT (32 ± 151), without differences between IFS-MAR and DECT (p < 0.553). Compared to FBP, qualitative artefacts were significantly reduced using IFS-MAR (p < 0.001) and DECT (p < 0.05), without significant differences between IFS-MAR and DECT (p < 0.219). Image quality significantly (p = 0.016) improved for IFS-MAR and DECT compared to FBP, without significant differences between IFS-MAR and DECT (p < 0.553). The level of confidence for screw tip localization was assessed as best for DECT in all cases.
  
  
  CONCLUSIONS
  Both IFS-MAR in SECT and mono-energetic DECT produce improved image quality and a reduction of metal artefacts. Screw tip positions can be most confidently assessed using DECT.
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland; Department of Forensic Medicine and Radiology, Institute of Forensic Medicine, University of Zurich, Switzerland. Electronic address: sebastian.winklhofer@usz.ch.
authors.forename: S
authors.initials: S
authors.lastname: Winklhofer
authors.affiliation: Department of Orthopedics and Traumatology, Kantonsspital St Gallen, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Benninger
authors.affiliation: Department of Orthopedics and Traumatology, Kantonsspital St Gallen, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Spross
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Morsbach
authors.affiliation: Department of Orthopedics and Traumatology, Kantonsspital St Gallen, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Rahm
authors.affiliation: Department of Forensic Medicine and Radiology, Institute of Forensic Medicine, University of Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Ross
authors.affiliation: Department of Orthopedics and Traumatology, Kantonsspital St Gallen, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Jost
authors.affiliation: Department of Forensic Medicine and Radiology, Institute of Forensic Medicine, University of Zurich, Switzerland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Thali
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland; Department of Forensic Medicine and Radiology, Institute of Forensic Medicine, University of Zurich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Stolzmann
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Alkadhi
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Guggenberger
mesh_terms: D016477:Artifacts; D002102:Cadaver; D005593:Fracture Fixation, Internal; D006801:Humans; D006811:Humerus / Q000473:pathology*; D008670:Metals; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012784:Shoulder Fractures / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D008670:Metals