title: CT angiographic analysis of carotid artery stenosis: comparison of manual assessment, semiautomatic vessel analysis, and digital subtraction angiography.
abstract: OBJECTIVE
  To compare multisection CT angiography (CTA) analyzed with source/maximum intensity projection (MIP) images as well as semiautomated vessel analysis software with intra-arterial digital subtraction angiography (DSA) in detection and grading of carotid artery bifurcation stenosis.
  
  
  METHODS
  Consecutive patients with sonography evidence of a marked internal carotid artery stenosis underwent both carotid CTA and DSA (37 patients, 73 vessels). In CTA, the grade of stenosis was determined using axial source and MIP images as well as vessel analysis. The scans were blind-analyzed by 2 neuroradiologists using the NASCET criteria.
  
  
  RESULTS
  Correlation of CTA source/MIP images versus DSA estimates of stenosis (R = 0.95) was higher than for the vessel analysis method versus DSA (R = 0.89). Compared with DSA, CTA source/MIP images underestimated high (78.2% versus 86.4%, P < .05) and moderate grades of stenosis (57.3% versus 63.1%, P < .05) to a lesser extent than the vessel analysis method (68.5% versus 83.5% and 51.8% versus 63.1%, P < .05). For a high-grade stenosis, sensitivity and specificity of source/MIP image CTA were 75% and 96%, respectively, whereas for the vessel analysis method, they were 47% and 96%, respectively. For moderate stenosis, the source/MIP image CTA sensitivity and specificity were 88% and 82%, respectively, and for vessel analysis method, 62% and 82%, respectively. CTA detected all 4 occlusions.
  
  
  CONCLUSIONS
  In evaluation of carotid stenosis, CTA provides an adequate, less invasive alternative with a high correlation to conventional DSA, though it tends to underestimate clinically relevant grades of stenosis. Its accuracy is not improved by semiautomated analysis. The data support the use of CTA in confirming carotid occlusion.
authors.affiliation: Helsinki Medical Imaging Center, University of Helsinki, Helsinki University Central Hospital, Department of Radiology, Helsinki, Finland. heli.silvennoinen@hus.fi
authors.forename: H M
authors.initials: HM
authors.lastname: Silvennoinen
authors.forename: S
authors.initials: S
authors.lastname: Ikonen
authors.forename: L
authors.initials: L
authors.lastname: Soinne
authors.forename: M
authors.initials: M
authors.lastname: Railo
authors.forename: L
authors.initials: L
authors.lastname: Valanne
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D002114:Calcinosis / Q000000981:diagnostic imaging; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000601:surgery; D016893:Carotid Stenosis / Q000145:classification / Q000000981:diagnostic imaging* / Q000601:surgery; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed