title: Intracranial aneurysms: CT angiography and MR angiography for detection prospective blinded comparison in a large patient cohort.
abstract: OBJECTIVE
  To compare computed tomographic (CT) angiography and magnetic resonance (MR) angiography with intraarterial digital subtraction angiography (DSA) in the detection of intracranial aneurysms.
  
  
  METHODS
  One hundred forty-two patients underwent intraarterial DSA to detect aneurysms. CT angiography, three-dimensional time-of-flight MR angiography, and intraarterial DSA were performed contemporaneously. Film hard-copy images and maximum intensity projection reconstructions of the CT angiograms and MR angiograms were reviewed at different times.
  
  
  RESULTS
  The accuracy per patient for the best observer was 0.87 at CT angiography and 0.85 at MR angiography. The accuracy per aneurysm for the best observer was 0.73 at CT angiography and 0.67 at MR angiography. Differences between readers and modalities were not significant. Interobserver agreement was good: kappa value of 0.73 for CT angiography and of 0.74 for MR angiography. The sensitivity for detection of aneurysms smaller than 5 mm was 0.57 for CT angiography and 0.35 for MR angiography compared with 0.94 and 0.86, respectively, for detection of aneurysms 5 mm or larger. The accuracy of both CT angiography and MR angiography was lower for detection of internal carotid artery aneurysms compared with that at other sites. With low observer confidence, the likelihood of correct interpretation was significantly poorer.
  
  
  CONCLUSIONS
  CT angiography and MR angiography have limited sensitivity in the detection of small aneurysms but good interobserver agreement. There is no significant difference in diagnostic performance between the noninvasive modalities.
authors.affiliation: University Department of Neurosurgery and Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, Scotland. pmw@skull.dcn.ed.ac.uk
authors.forename: P M
authors.initials: PM
authors.lastname: White
authors.forename: E M
authors.initials: EM
authors.lastname: Teasdale
authors.forename: J M
authors.initials: JM
authors.lastname: Wardlaw
authors.forename: V
authors.initials: V
authors.lastname: Easton
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000000981:diagnostic imaging; D018810:Magnetic Resonance Angiography; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed