title: Quantifying Intracranial Internal Carotid Artery Stenosis on MR Angiography.
abstract: OBJECTIVE
  Intracranial atherosclerosis is a common cause of ischemic stroke. Intracranial stenosis is most commonly quantified by the Warfarin-Aspirin Symptomatic Intracranial Disease method, which involves calculating a ratio of luminal diameter measurements on conventional angiography. Our purpose was to determine whether a single linear measurement of the narrowest caliber of the intracranial ICA on MRA can accurately predict Warfarin-Aspirin Symptomatic Intracranial Disease stenosis measurements.
  
  
  METHODS
  We identified patients from a prospective stroke registry who had undergone head MRAs to quantitatively evaluate the degree of Warfarin-Aspirin Symptomatic Intracranial Disease-derived stenosis in each intracranial ICA. We also made a single linear millimeter measurement at the site of maximal narrowing of the ICA. We calculated a correlation coefficient between the lumen diameter in millimeters and percentage Warfarin-Aspirin Symptomatic Intracranial Disease stenosis. We performed receiver operating characteristic analysis to determine optimal luminal diameter cutoff values.
  
  
  RESULTS
  In 386 unique intracranial ICAs, we found a strong linear relationship between single lumen measurements and Warfarin-Aspirin Symptomatic Intracranial Disease-style stenosis measurements (R= -0.84,P< .0001). We found that ICA lumen diameters of ≤2.1 and ≤1.3 mm were optimal cutoffs for identifying patients with ≥50% stenosis and ≥70% stenosis, respectively (area under the curve = 0.96 and 0.99, respectively).
  
  
  CONCLUSIONS
  There is a strong linear relationship between the narrowest lumen diameter of the intracranial ICA and percentage stenosis. Our results suggest that a single lumen diameter measurement on MRA allows accurate estimation of Warfarin-Aspirin Symptomatic Intracranial Disease stenosis, which may affect risk stratification and treatment decisions.
authors.affiliation: From the Department of Radiology (H.B., P.P., K.A.-D., A. Gupta).|Clinical and Translational Neuroscience Unit (H.B., G.G., H.K., A. Gupta).
authors.forename: H
authors.identifier: http://orcid.org/0000-0002-6251-5769
authors.initials: H
authors.lastname: Baradaran
authors.affiliation: From the Department of Radiology (H.B., P.P., K.A.-D., A. Gupta).
authors.forename: P
authors.identifier: http://orcid.org/0000-0002-5464-5272
authors.initials: P
authors.lastname: Patel
authors.affiliation: Clinical and Translational Neuroscience Unit (H.B., G.G., H.K., A. Gupta).
authors.forename: G
authors.identifier: http://orcid.org/0000-0001-6203-0334
authors.initials: G
authors.lastname: Gialdini
authors.affiliation: From the Department of Radiology (H.B., P.P., K.A.-D., A. Gupta).
authors.forename: K
authors.identifier: http://orcid.org/0000-0001-5737-1345
authors.initials: K
authors.lastname: Al-Dasuqi
authors.affiliation: Feil Family Brain and Mind Research Institute, Department of Healthcare Policy and Research (A. Giambrone).
authors.forename: A
authors.identifier: http://orcid.org/0000-0003-4498-8471
authors.initials: A
authors.lastname: Giambrone
authors.affiliation: Clinical and Translational Neuroscience Unit (H.B., G.G., H.K., A. Gupta).|Department of Neurology (H.K.), Weill Cornell Medicine, New York, New York.
authors.forename: H
authors.identifier: http://orcid.org/0000-0002-5745-0307
authors.initials: H
authors.lastname: Kamel
authors.affiliation: From the Department of Radiology (H.B., P.P., K.A.-D., A. Gupta) ajg9004@med.cornell.edu.|Clinical and Translational Neuroscience Unit (H.B., G.G., H.K., A. Gupta).
authors.forename: A
authors.identifier: http://orcid.org/0000-0003-2816-0340
authors.initials: A
authors.lastname: Gupta
mesh_terms: D000368:Aged; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies