title: Dual-energy computed tomography arthrography of the shoulder joint using virtual monochromatic spectral imaging: optimal dose of contrast agent and monochromatic energy level.
abstract: OBJECTIVE
  To optimize the dose of contrast agent and the level of energy for dual-energy computed tomography (DECT) arthrography of the shoulder joint and to evaluate the benefits of the optimized imaging protocol.
  
  
  METHODS
  Dual-energy scans with monochromatic spectral imaging mode and conventional single energy scans were performed on a shoulder phantom with 10 concentrations from 0 to 210 mg/mL of iodinated contrast medium at intervals of 15 or 30 mg/mL. Image noise, tissue contrast, and beam hardening artifacts were assessed to determine the optimum dose of contrast agent and the level of monochromatic energy for DECT shoulder arthrography in terms of the lowest image noise and the least beam hardening artifacts while good tissue contrast was maintained. Material decomposition (MD) imaging for bone-iodine differentiation was qualitatively assessed. The optimized protocol was applied and evaluated in 23 patients.
  
  
  RESULTS
  The optimal contrast dose and energy level were determined by the phantom study at 60 mg/mL and 72 keV, respectively. This optimized protocol for human study reduced the image noise and the beam-hardening artifacts by 35.9% and 44.5%, respectively. Bone-iodine differentiation by MD imaging was not affected by the iodine concentration or level of energy.
  
  
  CONCLUSIONS
  Dual-energy scan with monochromatic spectral imaging mode results in reduced image noise and beam hardening artifacts.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Chansik
authors.initials: C
authors.lastname: An
authors.affiliation: Department of Orthopedic Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Chun
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 135-720, Korea.
authors.forename: Sungjun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.affiliation: GE Healthcare, Seoul 135-820, Korea.
authors.forename: Min Jeong
authors.initials: MJ
authors.lastname: Yun
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Jin-Suck
authors.initials: JS
authors.lastname: Suh
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Ho-Taek
authors.initials: HT
authors.lastname: Song
mesh_terms: D000704:Analysis of Variance; D016477:Artifacts; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: Dual energy computed tomography; Gemstone spectral imaging; Shoulder arthrography