title: Recognizing subtle near-occlusion in carotid stenosis patients: a computed tomography angiographic study.
abstract: BACKGROUND
  Near-occlusion of the internal carotid artery (ICA) is a significant luminal diameter (LD) reduction beyond a tight atherosclerotic carotid stenosis (CS). Recognition of even subtle near-occlusions is essential to prevent underestimation of the stenosis degree. Our goal was to investigate the prevalence of near-occlusion among CS patients using a single standard criterion to facilitate its recognition, even when distal ICA LD reduction is not visually evident in computed tomography angiography (CTA).
  
  
  METHODS
  We analysed carotid artery CTAs of 467 patients with moderate-to-severe CS scheduled for endarterectomy. We performed measurements of the bilateral distal ICA LDs from thin axial source images and utilized a 1.0 mm intra-individual side-to-side distal ICA LD difference to distinguish near-occlusions, based on a previous study, aware of the vagaries of measurement. For analysis stratification, we excluded cases with significant carotid pathology affecting LD measurements.
  
  
  RESULTS
  We discovered 126 near-occlusions fulfilling our criterion of ipsilateral near-occlusion: the mean LD side-to-side difference (mm) with 95% confidence interval being 1.8 (1.6, 1.9) and a standard deviation of 0.8 mm. Among the 233 cases not meeting our near-occlusion criterion, we found 140 moderate (50-69%) and 93 severe (70-99%) ipsilateral stenoses.
  
  
  CONCLUSIONS
  The utilization of 1.0 mm cut-off value for the intra-individual distal ICA LD side-to-side difference to distinguish atherosclerotic ICA near-occlusion leads to a relatively high incidence of near-occlusion. In CTA, recently suggested to be used for near-occlusion diagnosis, a discriminatory 1.0 mm cut-off value could function as a pragmatic tool to enhance the detection of even subtle near-occlusions.
authors.affiliation: Clinicum, Department of Neurosciences, University of Helsinki, Haartmaninkatu 8, Biomedicum 1 Helsinki, Room B412b, PO Box 700, 00029 HUS, Helsinki, Finland. suvi.koskinen@helsinki.fi.|HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. suvi.koskinen@helsinki.fi.
authors.forename: Suvi Maaria
authors.initials: SM
authors.lastname: Koskinen
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Heli
authors.initials: H
authors.lastname: Silvennoinen
authors.affiliation: Neurology, Clinical Neurosciences, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.|Molecular Neurology, Research Programs Unit, University of Helsinki, Helsinki, Finland.
authors.forename: Petra
authors.initials: P
authors.lastname: Ijäs
authors.affiliation: Neurology, Clinical Neurosciences, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.|Molecular Neurology, Research Programs Unit, University of Helsinki, Helsinki, Finland.
authors.forename: Krista
authors.initials: K
authors.lastname: Nuotio
authors.affiliation: HUS Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Valanne
authors.affiliation: Neurology, Clinical Neurosciences, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.|Molecular Neurology, Research Programs Unit, University of Helsinki, Helsinki, Finland.
authors.forename: Perttu J
authors.initials: PJ
authors.lastname: Lindsberg
authors.affiliation: Neurology, Clinical Neurosciences, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Soinne
mesh_terms: D000368:Aged; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D000072226:Computed Tomography Angiography; D005260:Female; D006801:Humans; D008297:Male; D011857:Radiographic Image Interpretation, Computer-Assisted; D012720:Severity of Illness Index
keywords: Atherosclerosis; Carotid stenosis; Computed tomography angiography; Near-occlusion