title: The utility of quantitative magnetic resonance angiography in the assessment of intracranial in-stent stenosis.
abstract: OBJECTIVE
  Noninvasive screening for intracranial in-stent stenosis is often limited by artifact because of the stent or associated coils. We aimed to determine the utility of quantitative MRA (QMRA) as a screening tool for detecting intracranial in-stent stenosis.
  
  
  METHODS
  We reviewed 14 patients who had intracranial stent placement with follow-up QMRA and conventional angiography at our institution. Socio-demographic, medical, clinical, and imaging data were abstracted from medical charts. A blinded interventional neurologist reviewed all angiograms for presence of >50% in-stent stenosis. We tested QMRA (mL/min) at varying thresholds as a predictor of angiographic results.
  
  
  RESULTS
  Among 14 patients (mean age, 62 years; 12 female, 2 male), 13 patients had Neuroform stents placed for wide-neck cerebral aneurysms and 1 patient had a Wingspan stent placement for atherosclerotic stenosis. Lesions were located in the intracranial internal carotid artery in 57.2% (n=8), the middle cerebral artery in 14.3% (n=2), and vertebrobasilar arteries in 28.6% (n=4). On follow-up angiography, 2 patients (14.3%) had >50% in-stent stenosis on angiography. Time-of-flight MRA was nondiagnostic in each case because of artifact from the stent or coils. A >20% reduction in vessel-specific blood flow by QMRA was associated with presence of >50% in-stent stenosis on angiography (P=0.033). As a screening tool to predict >50% angiographic in-stent stenosis, the sensitivity, specificity, positive predictive value, and negative predictive value of QMRA were 100%, 92%, 67%, and 100%, respectively.
  
  
  CONCLUSIONS
  We found that QMRA is a promising screening tool to detect intracranial in-stent stenosis. Future prospective studies should focus on whether QMRA has a role in the detection of radiographic restenosis and prediction of clinical events.
authors.forename: Shyam
authors.initials: S
authors.lastname: Prabhakaran
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Warrior
authors.forename: Kalani R
authors.initials: KR
authors.lastname: Wells
authors.forename: Miral D
authors.initials: MD
authors.lastname: Jhaveri
authors.forename: Michael
authors.initials: M
authors.lastname: Chen
authors.forename: Demetrius K
authors.initials: DK
authors.lastname: Lopes
mesh_terms: D000368:Aged; D016477:Artifacts; D050197:Atherosclerosis / Q000473:pathology / Q000601:surgery; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000175:diagnosis*; D003251:Constriction, Pathologic / Q000473:pathology / Q000601:surgery; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis*; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D015607:Stents; D014715:Vertebrobasilar Insufficiency / Q000601:surgery