title: What is the most sensitive non-invasive imaging strategy for the diagnosis of intracranial aneurysms?
abstract: OBJECTIVE
  To determine whether combining non-invasive tests for intracranial aneurysms together would significantly improve aneurysm detection over individual tests.
  
  
  METHODS
  114 patients undergoing intra-arterial digital subtraction angiography to confirm or exclude an intracranial aneurysm were also examined by CT angiography, MR angiography, and transcranial power Doppler ultrasound. The reviewers and ultrasonographers were blinded to the angiogram result, other imaging results and all clinical information.
  
  
  RESULTS
  The combination of non-invasive tests did improve diagnostic performance on a per patient basis. The combination of power Doppler and CT angiography had the greatest sensitivity for aneurysm detection (0.83; 05% confidence interval (95% CI) 0.66-0.93) and the level of agreement for this strategy with the reference angiographic standard was excellent (kappa 0.84; 95% CI 0.72-0.95). The improvement in sensitivity of adding power Doppler to CT angiography was not significant (p=0.55) but the improvement in the level of agreement with the reference standard was substantial. However, even the most sensitive combination strategy performed poorly in the detection of small (3-5 mm) and very small (<3 mm) aneurysms with a sensitivity of 0.43 (95% CI 0.23-0.66) and 0.00 (95% CI 0.00-0.31) respectively.
  
  
  CONCLUSIONS
  The addition of transcranial power Doppler ultrasound to either CT angiography or MR angiography does improve diagnostic performance on a per patient basis but aneurysms of 5 mm or smaller can still not be reliably identified by current standard clinical non-invasive imaging modalities.
authors.affiliation: University Department of Neurosurgery and Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow G52 4TF, UK. pmw@skull.dcn.ed.ac.uk
authors.forename: P M
authors.initials: PM
authors.lastname: White
authors.forename: E
authors.initials: E
authors.lastname: Teadsale
authors.forename: J M
authors.initials: JM
authors.lastname: Wardlaw
authors.forename: V
authors.initials: V
authors.lastname: Easton
mesh_terms: D000328:Adult; D000368:Aged; D002533:Cerebral Angiography / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010146:Pain / Q000175:diagnosis / Q000209:etiology; D010147:Pain Measurement; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D017585:Ultrasonography, Doppler, Transcranial / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods / Q000592:standards*