title: Detection of circle of Willis aneurysms in patients with acute subarachnoid hemorrhage: a comparison of CT angiography and digital subtraction angiography.
abstract: OBJECTIVE
  The purpose of this study was to compare CT angiography with digital subtraction angiography (DSA) in the detection and measurement of intracranial aneurysms in patients with acute subarachnoid hemorrhage.
  
  
  METHODS
  Thirty consecutive patients with recent subarachnoid hemorrhage shown by unenhanced CT scanning or lumbar puncture were studied with CT angiography and DSA. Using a shaded surface display format and source images, two reviewers working independently blindly interpreted CT angiograms for presence and size of aneurysms. Sensitivity and specificity for aneurysm detection were calculated for each reviewer. Aneurysm size measurements were compared between reviewers and between the two imaging techniques.
  
  
  RESULTS
  Thirty aneurysms were found in 22 patients with DSA; eight patients had no aneurysms. The sensitivity and specificity of CT angiography for reviewer A were 0.97 and 1.0, respectively. For reviewer B, the sensitivity and specificity were 0.77 and 0.87, respectively. All cases with single aneurysms on DSA (18 patients) had surgical confirmation of aneurysm location and rupture. In each case with multiple aneurysms (four patients), the aneurysm thought responsible for the hemorrhage was surgically confirmed. In those cases with no aneurysms found on DSA, follow-up DSA studies did not reveal additional findings. Differences between reviewers in aneurysm size measurements made with CT angiography were not significant (p = .10). Mean aneurysm measurements for reviewer A, reviewer B, and DSA were 6.6 mm, 7.0 mm, and 6.9 mm, respectively.
  
  
  CONCLUSIONS
  CT angiography shows potential in the detection and measurement of aneurysms in patients with acute subarachnoid hemorrhage when compared with DSA.
authors.affiliation: Department of Radiology, University of Vermont Medical Center Hospital, Burlington 05401, USA.
authors.forename: P T
authors.initials: PT
authors.lastname: Vieco
authors.forename: W P
authors.initials: WP
authors.lastname: Shuman
authors.forename: G F
authors.initials: GF
authors.lastname: Alsofrom
authors.forename: C E
authors.initials: CE
authors.lastname: Gross
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D017542:Aneurysm, Ruptured / Q000150:complications / Q000000981:diagnostic imaging*; D015901:Angiography, Digital Subtraction / Q000295:instrumentation / Q000379:methods; D002533:Cerebral Angiography / Q000295:instrumentation / Q000379:methods; D002941:Circle of Willis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012422:Rupture, Spontaneous; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging* / Q000209:etiology; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods