title: Prospective evaluation of multidetector-row CT angiography for the diagnosis of vasospasm following subarachnoid hemorrhage: a comparison with digital subtraction angiography.
abstract: OBJECTIVE
  To evaluate the accuracy of multidetector-row CT angiography (CTA) for the diagnosis of large-vessel vasospasm following subarachnoid hemorrhage by comparison to digital subtraction angiography (DSA).
  
  
  METHODS
  Thirty-three patients with acute subarachnoid hemorrhage were enrolled in a prospective study and underwent a total of 40 CTA and DSA examinations within 24 h of each other. Two neuroradiologists reviewed the CTA examinations independently. A third neuroradiologist blinded to the CTA results reviewed the DSA examinations. In each patient, for both techniques, 23 arterial segments were evaluated for their degree of narrowing; the reviewers were asked to attribute every narrowing to 'vasospasm' or 'hypoplasia'. Agreement between CTA and DSA for the degree of narrowing, and agreement between the two CTA readers, were calculated using weighted kappa-coefficients. Sensitivity, specificity, accuracy, positive and negative predictive value (NPV) of CTA to detect large-vessel vasospasm were calculated considering DSA as the gold standard.
  
  
  RESULTS
  Substantial correlation (kappa = 0.638) was found between CTA and DSA for the detection of arterial narrowing. Interobserver agreement between the two CTA reviewers for the degree of luminal narrowing was substantial (kappa = 0.712).CTA was 87% accurate for the diagnosis of large-vessel vasospasm; the NPV of CTA was 95%. CTA was more accurate, and interobserver agreement higher, for the proximal arterial segments (basilar and vertebral arteries) than for the distal ones (P2 segments). Using CTA as a screening modality, 83% of unnecessary DSA would have been avoided.
  
  
  CONCLUSIONS
  Compared to the gold standard of DSA, CTA is accurate for the detection of large-vessel vasospasm, and has a very high NPV.
authors: Neuroradiology Section, Department of Radiology, University of California, San Francisco, CA 94143-0628, USA.
authors: Saadia R
authors: SR
authors: Chaudhary
authors: Nerissa
authors: N
authors: Ko
authors: William P
authors: WP
authors: Dillon
authors: Melissa B
authors: MB
authors: Yu
authors: Songling
authors: S
authors: Liu
authors: Geoffrey I
authors: GI
authors: Criqui
authors: Randall T
authors: RT
authors: Higashida
authors: Wade S
authors: WS
authors: Smith
authors: Max
authors: M
authors: Wintermark
mesh_terms: D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D020301:Vasospasm, Intracranial / Q000000981:diagnostic imaging* / Q000209:etiology