title: Single-source dual-energy computed tomography: use of monoenergetic extrapolation for a reduction of metal artifacts.
abstract: OBJECTIVE
  The objective of this study was to retrospectively determine the potential of virtual monoenergetic (ME) reconstructions for a reduction of metal artifacts using a new-generation single-source computed tomographic (CT) scanner.
  
  
  METHODS
  The ethics committee of our institution approved this retrospective study with a waiver of the need for informed consent. A total of 50 consecutive patients (29 men and 21 women; mean [SD] age, 51.3 [16.7] years) with metal implants after osteosynthetic fracture treatment who had been examined using a single-source CT scanner (SOMATOM Definition Edge; Siemens Healthcare, Forchheim, Germany; consecutive dual-energy mode with 140 kV/80 kV) were selected. Using commercially available postprocessing software (syngo Dual Energy; Siemens AG), virtual ME data sets with extrapolated energy of 130 keV were generated (medium smooth convolution kernel D30) and compared with standard polyenergetic images reconstructed with a B30 (medium smooth) and a B70 (sharp) kernel. For quantification of the beam hardening artifacts, CT values were measured on circular lines surrounding bone and the osteosynthetic device, and frequency analyses of these values were performed using discrete Fourier transform. A high proportion of low frequencies to the spectrum indicates a high level of metal artifacts. The measurements in all data sets were compared using the Wilcoxon signed rank test.
  
  
  RESULTS
  The virtual ME images with extrapolated energy of 130 keV showed significantly lower contribution of low frequencies after the Fourier transform compared with any polyenergetic data set reconstructed with D30, B70, and B30 kernels (P < 0.001).
  
  
  CONCLUSIONS
  Sequential single-source dual-energy CT allows an efficient reduction of metal artifacts using high-energy ME extrapolation after osteosynthetic fracture treatment.
authors: From the Departments of *Diagnostic and Interventional Radiology, and †Traumatology, Eberhard Karls University Tuebingen, Tuebingen; and ‡Computed Tomography, Siemens Healthcare, Forchheim, Germany.
authors: Stefanie
authors: S
authors: Mangold
authors: Sergios
authors: S
authors: Gatidis
authors: Oliver
authors: O
authors: Luz
authors: Benjamin
authors: B
authors: König
authors: Christoph
authors: C
authors: Schabel
authors: Malte N
authors: MN
authors: Bongers
authors: Thomas G
authors: TG
authors: Flohr
authors: Claus D
authors: CD
authors: Claussen
authors: Christoph
authors: C
authors: Thomas
mesh_terms: D000328:Adult; D000368:Aged; 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 / Q000379:methods*
chemical_list: D008670:Metals