title: 3.0 Tesla contrast-enhanced MR angiography of carotid artery stents: in vitro measurements as compared with 1.5 Tesla.
abstract: OBJECTIVE
  To assess the appearance of carotid artery stents at 3.0 Tesla contrast enhanced magnetic resonance angiography (CE-MRA) as compared with 1.5 Tesla.
  
  
  METHODS
  19 stents (GUIDANT Acculink, GUIDANT Dynalink, BOSTON SCIENTIFIC SMART Neuroform, GUIDANT Omnilink, EV3 Protege, BOSTON SCIENTIFIC Carotid Wallstent, ABBOTT Xact) of different materials (nitinol, stainless steal, cobalt alloy) and different sizes (4.0 mm-10.0 mm) were investigated regarding their appearance on CE-MRA at 3.0 Tesla and at 1.5 Tesla. For each stent artificial lumen narrowing (ALN) was calculated based on a pixel-by-pixel profile of the contrast-to-noise-ratio giving an objective indicator for the size of the evaluable stent diameter.
  
  
  RESULTS
  Only in two stents (Omnilink 7.0 mm, Omnilink 10.0 mm) was ALN higher at 3.0 Tesla relative to 1.5 Tesla. In all other stents ALN at 3.0 Tesla was the same or even lower as compared with 1.5 Tesla. In contrast to the ferromagnetic stents where ALN was typically higher than 85%, in most of the nitinol stents (Acculink, Dynalink, Neuroform, Protege) ALN was below 35%. In the Xact stents ALN was generally 100% at 1.5 Tesla and ranged between 31.8% and 100% at 3.0 Tesla.
  
  
  CONCLUSIONS
  CE-MRA after carotid artery stenting is considerably impaired by ALN both at 1.5 Tesla and at 3.0 Tesla. Nevertheless, CE-MRA is well suited for the examination of carotid artery stents made of nitinol at both field strengths. Stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic methods such as CE-MRA.
authors.affiliation: Division of Neuroradiology, Department of Neurology, University of Heidelberg Medical Center, Im Neuenheimer Feld 400, D 69120 Heidelberg, Germany. Stefan_Haehnel@med.uni-heidelberg.de
authors.forename: S
authors.initials: S
authors.lastname: Hähnel
authors.forename: T H
authors.initials: TH
authors.lastname: Nguyen-Trong
authors.forename: S
authors.initials: S
authors.lastname: Rohde
authors.forename: M
authors.initials: M
authors.lastname: Hartmann
authors.forename: C
authors.initials: C
authors.lastname: Braun
authors.forename: K
authors.initials: K
authors.lastname: Sartor
authors.forename: S
authors.initials: S
authors.lastname: Heiland
mesh_terms: D000497:Alloys; D016477:Artifacts; D002339:Carotid Arteries; D003035:Cobalt; D003287:Contrast Media; D006801:Humans; D066298:In Vitro Techniques; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019047:Phantoms, Imaging; D013193:Stainless Steel; D015607:Stents; D020521:Stroke / Q000517:prevention & control
chemical_list: D000497:Alloys; D003287:Contrast Media; D013193:Stainless Steel; C013616:nitinol; D003035:Cobalt