title: In vivo evaluation of the carotid wallstent on three-dimensional contrast material-enhanced MR angiography: influence of artifacts on the visibility of stent lumina.
abstract: OBJECTIVE
  Contrast material-enhanced magnetic resonance (MR) angiography is increasingly used in postinterventional imaging after implantation of endovascular stents. The main limitations are stent-related artifacts compromising the visibility of the stent lumen. The aim of this in vivo study is the evaluation of contrast-enhanced MR angiography imaging characteristics of the carotid Wallstent.
  
  
  METHODS
  The carotid arteries of 29 patients were examined with contrast-enhanced MR angiography 3-6 days and/or 7-23 months after implantation of a carotid Wallstent into the internal carotid artery. Images were evaluated with regard to the diameter and signal intensity (SI) of the visible stent lumen. Digital subtraction angiography (DSA) was used as the standard of reference.
  
  
  RESULTS
  Stent-related artifacts on contrast-enhanced MR angiography caused an artificial lumen narrowing and a reduction of the SI within the stent. Artifacts were pronounced on imaging 3-6 days after stent implantation, but 68% of stents imaged 7-23 months after stent implantation presented with a significantly decreased artificial signal reduction and an improved visibility of the stent lumen.
  
  
  CONCLUSIONS
  The results of this study indicate that a reliable evaluation of the stent lumen is limited as a result of an artificial decrease of the SI inside the stent. However, in follow-up examinations 7-23 months after stent implantation, visibility of the stent lumen was improved and diagnostic reliability of contrast-enhanced MR angiography was markedly increased. A probable explanation for this phenomenon might be the formation of a neointimal layer covering the stent struts and thereby reducing stent-related artifacts.
authors.affiliation: Department of Diagnostic Radiology, University Hospital Regensburg, Germany. ingitha@web.de
authors.forename: Ingitha
authors.initials: I
authors.lastname: Borisch
authors.forename: Okka W
authors.initials: OW
authors.lastname: Hamer
authors.forename: Niels
authors.initials: N
authors.lastname: Zorger
authors.forename: Stefan
authors.initials: S
authors.lastname: Feuerbach
authors.forename: Johann
authors.initials: J
authors.lastname: Link
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D016477:Artifacts; D016893:Carotid Stenosis / Q000601:surgery*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D049671:History, 18th Century; D006801:Humans; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015641:Radiography, Interventional; D018709:Statistics, Nonparametric; D015607:Stents; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA