title: Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel controls.
abstract: OBJECTIVE
  To evaluate metal artifacts induced by biodegradable magnesium--a new class of degradable biomaterial that is beginning to enter the orthopedic routine--on CT and MRI compared to standard titanium and steel controls.
  
  
  METHODS
  Different pins made of titanium, stainless steel, and biodegradable magnesium alloys were scanned using a second-generation dual-energy multidetector CT and a 1.5-T MR scanner. In CT, quantitative assessment of artifacts was performed by two independent readers by measuring the noise in standardized regions of interest close to the pins. In MRI, the artifact diameter was measured. Interobserver agreement was evaluated using intraclass correlation coefficients. Artifacts were compared using Mann Whitney U tests.
  
  
  RESULTS
  In comparison to stainless steel, biodegradable magnesium alloys induced significantly fewer artifacts in both 1.5-T MRI (p = 0.019-0.021) and CT (p = 0.003-0.006). Compared to titanium, magnesium induced significantly less artifact-related noise in CT (p = 0.003-0.008). Although artifacts were less on MRI for biodegradable magnesium compared to titanium, this result was not statistically significant.
  
  
  CONCLUSIONS
  Biodegradable magnesium alloys induce substantially fewer artifacts in CT compared to standard titanium and stainless steel, and fewer artifacts in MRI for the comparison with stainless steel.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Zurich, Ramistrasse 100, 8091, Zurich, Switzerland, lukas.filli@usz.ch.
authors.forename: Lukas
authors.initials: L
authors.lastname: Filli
authors.forename: Roger
authors.initials: R
authors.lastname: Luechinger
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
authors.forename: Stefan
authors.initials: S
authors.lastname: Beck
authors.forename: Roman
authors.initials: R
authors.lastname: Guggenberger
authors.forename: Nadja
authors.initials: N
authors.lastname: Farshad-Amacker
authors.forename: Gustav
authors.initials: G
authors.lastname: Andreisek
mesh_terms: D020341:Absorbable Implants; D000497:Alloys; D016477:Artifacts; D001858:Bone Nails; D008274:Magnesium; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D008670:Metals; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013193:Stainless Steel; D014025:Titanium; D014057:Tomography, X-Ray Computed
chemical_list: D000497:Alloys; D008670:Metals; D013193:Stainless Steel; D014025:Titanium; D008274:Magnesium