title: Metal implants on CT: comparison of iterative reconstruction algorithms for reduction of metal artifacts with single energy and spectral CT scanning in a phantom model.
abstract: To assess single energy metal artifact reduction (SEMAR) and spectral energy metal artifact reduction (MARS) algorithms in reducing artifacts generated by different metal implants.
  
  
  
  Phantom was scanned with and without SEMAR (Aquilion One, Toshiba) and MARS (Discovery CT750 HD, GE), with various metal implants. Images were evaluated objectively by measuring standard deviation in regions of interests and subjectively by two independent reviewers grading on a scale of 0 (no artifact) to 4 (severe artifact). Reviewers also graded new artifacts introduced by metal artifact reduction algorithms.
  
  
  
  SEMAR and MARS significantly decreased variability of the density measurement adjacent to the metal implant, with median SD (standard deviation of density measurement) of 52.1 HU without SEMAR, vs. 12.3 HU with SEMAR, p < 0.001. Median SD without MARS of 63.1 HU decreased to 25.9 HU with MARS, p < 0.001. Median SD with SEMAR is significantly lower than median SD with MARS (p = 0.0011). SEMAR improved subjective image quality with reduction in overall artifacts grading from 3.2 ± 0.7 to 1.4 ± 0.9, p < 0.001. Improvement of overall image quality by MARS has not reached statistical significance (3.2 ± 0.6 to 2.6 ± 0.8, p = 0.088). There was a significant introduction of artifacts introduced by metal artifact reduction algorithm for MARS with 2.4 ± 1.0, but minimal with SEMAR 0.4 ± 0.7, p < 0.001.
  
  
  
  CT iterative reconstruction algorithms with single and spectral energy are both effective in reduction of metal artifacts. Single energy-based algorithm provides better overall image quality than spectral CT-based algorithm. Spectral metal artifact reduction algorithm introduces mild to moderate artifacts in the far field.
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Jieming
authors.initials: J
authors.lastname: Fang
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Da
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Carol
authors.initials: C
authors.lastname: Wilcox
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Heidinger
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Raptopoulos
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Brook
authors.affiliation: Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA. obrook@bidmc.harvard.edu.
authors.forename: Olga R
authors.initials: OR
authors.lastname: Brook
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D008670:Metals; D019047:Phantoms, Imaging; D019736:Prostheses and Implants; D011857:Radiographic Image Interpretation, Computer-Assisted; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D008670:Metals
keywords: Computed tomography; Dual energy; Iterative reconstruction; Metal artifact reduction; Phantom comparison; Single energy