title: 'Susceptibility sign' on susceptibility-weighted imaging in acute ischemic stroke.
abstract: OBJECTIVE
  Acute intra-arterial thrombus produces susceptibility artifact on gradient echo images (susceptibility sign). Our aim was to study the sensitivity and specificity of the susceptibility sign in various major intracranial arteries on susceptibility-weighted imaging (SWI) in patients with acute stroke. We also compared it with the 'hyperintensity sign' on fluid-attenuated inversion recovery (FLAIR) and 'hyperdense artery sign' on computed tomography (CT) for middle cerebral artery (MCA) occlusion.
  
  
  METHODS
  We have retrospectively studied 48 patients with ischemic stroke in various stages, due to intracranial arterial occlusions, for presence of 'hyperdense artery sign' (CT), 'hyperintense arterial sign' (FLAIR sequence) and 'susceptibility sign' (SWI). The sensitivity and specificity of each sign to detect intracranial arterial occlusion were calculated using the contrast-enhanced magnetic resonance (MR) angiogram as reference standard.
  
  
  RESULTS
  The sensitivity and specificity of the 'susceptibility sign' for detecting the MCA occlusion were 77% and 100% respectively (10 of 13).The sensitivity of the 'susceptibility sign' for detecting anterior cerebral artery (ACA) occlusion was 50% (1 of 2), 66.6% for posterior cerebral artery (2 of 3) and 75% for basilar artery (3 of 4). All the vertebral artery occlusions showed 'susceptibility sign' (6 of 6). Overall sensitivity and specificity of the 'susceptibility sign' for all acute major intracranial arterial occlusions were 82% and 100% respectively. Only one of the two cases of subacute infarcts studied showed a positive susceptibility sign. None of the 11 chronic intracranial occlusions and seven internal carotid occlusions showed the sign intracranially.
  
  
  CONCLUSIONS
  'Susceptibility sign' is more sensitive in detecting the acute MCA thrombus as compared to 'hyperdense MCA sign' on CT and 'hyperintense artery' sign on FLAIR images. It also has high sensitivity and specificity for other intracranial acute arterial occlusions.
authors.affiliation: Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India.
authors.forename: Dayananda
authors.initials: D
authors.lastname: Lingegowda
authors.forename: Bejoy
authors.initials: B
authors.lastname: Thomas
authors.forename: Viratsinh
authors.initials: V
authors.lastname: Vaghela
authors.forename: Divyata Rajendra
authors.initials: DR
authors.lastname: Hingwala
authors.forename: Chandrasekharan
authors.initials: C
authors.lastname: Kesavadas
authors.forename: P N
authors.initials: PN
authors.lastname: Sylaja
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed