title: Non-enhanced magnetic resonance angiography can evaluate restenosis after carotid artery stenting with the Carotid Wallstent.
abstract: BACKGROUND
  Carotid artery stenting (CAS) requires follow-up imaging to assess in-stent restenosis (ISR). This study aimed to determine whether non-enhanced magnetic resonance angiography (NE-MRA) is useful for evaluating ISR.
  
  
  METHODS
  Between 2009 and 2013, we performed 118 consecutive CAS procedures using the Precise stent (n = 78) and the Carotid Wallstent (n = 40). We reviewed 1.5 T NE-MRA and examined visualization of the stent lumen and the degree of ISR if present. Other imaging modalities were used as references.
  
  
  RESULTS
  NE-MRA performed just after CAS was not able to visualize the stent lumen in all patients because of metal artifacts. In the Carotid Wallstent group, follow-up NE-MRA was available in 22 patients. The stent lumen was visible more than three months after CAS in all patients. Among them, >40 % ISR was observed by other modalities in eight lesions. The degree of restenosis measured by NE-MRA (y%) had a linear relationship with that measured by conventional angiography (x%) (y = 0.97x-0.4, r = 0.79, P = 0.021). In one case among 17 without ISR (6 %), NE-MRA showed false ISR. In the Precise stent group, NE-MRA did not visualize the stent lumen in the follow-up period.
  
  
  CONCLUSIONS
  NE-MRA can visualize the stent lumen in the Carotid Wallstent more than three months after CAS, but not in the Precise stent at follow-up. This delayed visualization might depend on endothelialization of the stent lumen. The degree of ISR measured by NE-MRA is comparable to that by conventional angiography. NE-MRA can evaluate ISR after CAS with the Carotid Wallstent (100 % sensitivity and 94 % specificity).
authors.affiliation: Department of Neurosurgery, Wakayama Rosai Hospital, 93-1 Kinomoto, Wakayama, 640-8505, Japan, vyr01450@gmail.com.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kono
authors.forename: Aki
authors.initials: A
authors.lastname: Shintani
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Terada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012680:Sensitivity and Specificity; D015607:Stents; D016896:Treatment Outcome; D014654:Vascular Patency