title: Helical CT for the diagnosis of extracranial internal carotid artery dissection.
abstract: OBJECTIVE
  We attempted to evaluate the sensitivity of helical CT for the diagnosis of extracranial internal carotid artery (ICA) dissection.
  
  
  METHODS
  Sixteen consecutive patients with 18 angiographically confirmed extracranial ICA dissections were studied with a helical CT protocol with large-volume acquisition and thin axial slice reconstructions. A control group including normal and atherosclerotic ICAs was formed for comparison, and a blind interpretation of CT images was made by two observers. We evaluated the presence of stenosis, eccentric lumen, mural thickening, aneurysm, occlusion, and annular contrast enhancement. When the artery seemed to be occluded, we measured the external diameter of the ICA (1) on the occluded side, at its upper portion and most enlarged level, (2) at its lower portion, beyond the bulb, and (3) on the contralateral side, at is upper portion.
  
  
  RESULTS
  Interobserver agreement was good except for the presence of annular contrast enhancement. In the stenotic dissection group (n=12), the presence of a narrowed eccentric lumen at the upper portion of the ICA on axial CT images was classified correctly in all cases (sensitivity, 100%; specificity, 100%). An arterial wall thickening was seen in all cases of dissection but also in three cases of the control group. In the occlusive dissection group (n=6), the enlargement of the dissected artery was the best criterion (sensitivity, 100%, specificity, 100%) for occlusive dissection.
  
  
  CONCLUSIONS
  Helical CT seems to be a reliable method for evaluating extracranial ICA dissection. The analysis of the residual arterial lumen and the measurement of the external diameter of the carotid artery were the best criteria for the diagnosis. Further studies with larger groups are required to determine whether ICA dissections might be diagnosed using helical CT as a first procedure.
authors.affiliation: Department of Radiology, University Hospital of Lille (France).
authors.forename: X
authors.initials: X
authors.lastname: Leclerc
authors.forename: O
authors.initials: O
authors.lastname: Godefroy
authors.forename: A
authors.initials: A
authors.lastname: Salhi
authors.forename: C
authors.initials: C
authors.lastname: Lucas
authors.forename: D
authors.initials: D
authors.lastname: Leys
authors.forename: J P
authors.initials: JP
authors.lastname: Pruvo
mesh_terms: D000328:Adult; D000784:Aortic Dissection / Q000000981:diagnostic imaging*; D000792:Angiography; D001161:Arteriosclerosis / Q000000981:diagnostic imaging; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging; D016893:Carotid Stenosis / Q000000981:diagnostic imaging; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media