title: Calcium at the carotid siphon as an indicator of internal carotid artery stenosis.
abstract: OBJECTIVE
  Carotid siphon calcification is often visible on unenhanced head CT (UCT), but the relation to proximal carotid artery stenosis (CAS) is unclear. We investigated the association of carotid siphon calcification with the presence of CAS.
  
  
  METHODS
  This IRB-waived retrospective study included 160 consecutive patients suspected of stroke (age 64 ± 14 years, 63 female) who underwent head UCT and CTA of the head and neck. CAS was rated on CTA as not present or present with non-significant (<50 %), moderate (50-69 %) or significant (≥70 %) stenosis. Presence, shape (on UCT) and volume (on CTA) of carotid siphon calcifications were related to CAS.
  
  
  RESULTS
  Carotid siphon calcification was absent in 41 % of patients and bilateral in 94 % of those with calcifications. Presence, shape and volume of calcification resulted in odds ratios for having significant CAS of 10.1, 3.9 and 8.4, with 95 % CIs of 1.3-79.6, 1.1-14.1 and 2.6-26.8, respectively. Corresponding NPVs were 0.98, 0.98 and 0.96, while PPVs were 0.14, 0.07 and 0.29, respectively.
  
  
  CONCLUSIONS
  Absence of calcification in the carotid artery siphon on UCT has high negative predictive value for carotid artery stenosis in patients with suspected stroke. However, siphon calcification is not a reliable indicator of significant carotid artery stenosis.
  
  
  CONCLUSIONS
  • Many stroke patients do not have calcification in the carotid artery siphon. • Carotid stenosis ≥50 % is unlikely in stroke patients without siphon calcification. • Carotid siphon calcium is a poor indicator of significant carotid artery stenosis.
authors: Department of Radiology, County hospital Požega, Osječka 107, 34000 Požega, Croatia. nikolagotovac@net.hr
authors: Nikola
authors: N
authors: Gotovac
authors: Ivana
authors: I
authors: Išgum
authors: Max A
authors: MA
authors: Viergever
authors: Geert J
authors: GJ
authors: Biessels
authors: Josip
authors: J
authors: Fajdić
authors: Birgitta K
authors: BK
authors: Velthuis
authors: Mathias
authors: M
authors: Prokop
mesh_terms: D000368:Aged; D002118:Calcium / Q000378:metabolism*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium