title: [Phantom studies using a high-resolution CT for ex-vivo imaging of degradable magnesium implants and simulated peri-implant bone formation in rabbit tibiae].
abstract: OBJECTIVE
  Evaluation of the suitability of the high-resolution CT XtremeCT for ex vivo imaging of degradable magnesium implants with simulated peri-implant bone formation in rabbit tibiae and development of a method for calibrating the mass concentration of a magnesium alloy in an implant volume.
  
  
  METHODS
  Using specially designed phantoms, degradable magnesium implants of the alloys LAE442, ZEK100, AX30 and MgCa 0.8 %, without coating and with peri-implant bone formation simulated by a coating, as well as rabbit tibiae were scanned. CT numbers and the contrast-to-noise-ratio (CNR) of the studied materials were determined. The visual distinction between implant and coating was evaluated. To calibrate the implant density, exemplary LAE442 pins with different mass concentrations were scanned using a specially constructed phantom. Subsequently, CT numbers corresponding to the appropriate mass concentration were determined.
  
  
  RESULTS
  The implants, coating and substantia corticalis showed a similar density. Visual distinction between coating and implant was strongly dependent on the respective magnesium alloy and chosen scan parameter. A CNR of at least 0.2 was required for a distinction between implant and coating. For the mass concentration, a high CT number linearity (R2=0.99) throughout the measuring range (1811-1273 mg/cm3 LAE442) was found.
  
  
  CONCLUSIONS
  As expected, the XtremeCT is primarily suitable for the imaging of bone tissue and implants. Good visual distinction of peri-implant bone formation on magnesium implants in an ex vivo phantom model ranges from possible to difficult depending on the bone density and alloy composition.
authors.affiliation: Fachgebiet Allgemeine Radiologie u. Medizinische Physik, Stiftung Tierärztliche Hochschule Hannover. jurriaan.schulman@me.com
authors.forename: J
authors.initials: J
authors.lastname: Schulman
authors.forename: A
authors.initials: A
authors.lastname: Meyer-Lindenberg
authors.forename: F
authors.initials: F
authors.lastname: Goblet
authors.forename: D
authors.initials: D
authors.lastname: Bormann
authors.forename: W
authors.initials: W
authors.lastname: Stiller
authors.forename: H
authors.initials: H
authors.lastname: Seifert
mesh_terms: D000497:Alloys / Q000737:chemistry; D000818:Animals; D020007:Implants, Experimental; D008274:Magnesium / Q000032:analysis; D010012:Osteogenesis; D019047:Phantoms, Imaging; D019736:Prostheses and Implants; D011817:Rabbits; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
chemical_list: D000497:Alloys; D008274:Magnesium