title: In vitro comparison of different carotid artery stents: a pixel-by-pixel analysis using CT angiography and contrast-enhanced MR angiography at 1.5 and 3 T.
abstract: BACKGROUND
  CT angiography (CTA) and MR angiography (MRA) are increasingly used methods for evaluation of stented vessel segments. The purpose of this study was to compare CTA, contrast-enhanced MRA (CEMRA) at 1.5 T, and CEMRA at 3 T for the visualization of carotid artery stents and to define the best noninvasive imaging technique for each stent.
  
  
  METHODS
  CTA and CEMRA appearances of 18 carotid artery stents of different designs and sizes (4.0 to 10.0 mm) were investigated in vitro. The profile of the contrast-to-noise ratio (CNR) of the lumen of each stent was calculated semiautomatically by a pixel-by-pixel analysis using the medical imaging software OSIRIS. For each stent, artificial lumen narrowing (ALN) was calculated.
  
  
  RESULTS
  In all but one stents, ALN was lower on CEMRA at 3 T than at 1.5 T. With CEMRA at 3 T and at 1.5 T, ALN in most nitinol stents was lower than in the groups of stainless steel and cobalt alloy stents. In most nitinol stents, ALN on CEMRA at 3 T was lower than on CTA. In all stainless steel stents and cobalt alloy stents, ALN was lower on CTA than on CEMRA. With CTA and CEMRA, in most stents ALN decreased with increasing stent diameter.
  
  
  CONCLUSIONS
  CTA and CEMRA evaluation of vessel patency after stent placement is possible, but considerably impaired by ALN. Investigators should be informed about the method of choice for every stent.
authors.affiliation: Division of Neuroradiology, Department of Neurology, University of Heidelberg, Medical Center, Im Neuenheimer Feld 400, Heidelberg, Germany. michael_lettau@gmx.de
authors.forename: Michael
authors.initials: M
authors.lastname: Lettau
authors.forename: Annett
authors.initials: A
authors.lastname: Sauer
authors.forename: Sabine
authors.initials: S
authors.lastname: Heiland
authors.forename: Stefan
authors.initials: S
authors.lastname: Rohde
authors.forename: Julia
authors.initials: J
authors.lastname: Reinhardt
authors.forename: Martin
authors.initials: M
authors.lastname: Bendszus
authors.forename: Stefan
authors.initials: S
authors.lastname: Hähnel
mesh_terms: D001807:Blood Vessel Prosthesis; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D003287:Contrast Media; D019544:Equipment Failure Analysis / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D015607:Stents; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media