Neuro

European Radiology

, Volume 23, Issue 6, pp 1478-1486

Calcium at the carotid siphon as an indicator of internal carotid artery stenosis

  • Nikola GotovacAffiliated withDepartment of Radiology, County hospital PožegaImage Sciences Institute, University Medical Center Utrecht Email author 
  • , Ivana IšgumAffiliated withImage Sciences Institute, University Medical Center Utrecht
  • , Max A. ViergeverAffiliated withImage Sciences Institute, University Medical Center Utrecht
  • , Geert J. BiesselsAffiliated withDepartment of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht
  • , Josip FajdićAffiliated withDepartment of Surgery, County hospital Požega
  • , Birgitta K. VelthuisAffiliated withDepartment of Radiology, University Medical Center Utrecht
  • , Mathias ProkopAffiliated withDepartment of Radiology, University Medical Center UtrechtDepartment of Radiology, Radboud University Nijmegen Medical Centre

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Abstract

Objectives

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.

Conclusion

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.

Key Points

Many stroke patients do not have calcification in the carotid artery siphon.

Carotid stenosis50 % is unlikely in stroke patients without siphon calcification.

Carotid siphon calcium is a poor indicator of significant carotid artery stenosis.

Keywords

Atherosclerosis Intracranial atherosclerosis Internal carotid artery Vascular calcification Carotid stenosis