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

• Published in: European radiology Vol. 23; no. 6; pp. 1478 - 1486
• Main Authors: Gotovac, Nikola, Išgum, Ivana, Viergever, Max A., Biessels, Geert J., Fajdić, Josip, Velthuis, Birgitta K., Prokop, Mathias
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2013; Springer Nature B.V
• Subjects: Aged; Atherosclerosis; Calcification; Calcium - metabolism; Carotid arteries; Carotid Artery, Internal - diagnostic imaging; Carotid Stenosis - diagnostic imaging; Diagnostic Radiology; Female; Humans; Image Processing, Computer-Assisted; Imaging; Internal Medicine; Interventional Radiology; Ischemia; Male; Medical imaging; Medicine; Medicine & Public Health; Middle Aged; Neuro; Neuroradiology; Observer Variation; Odds Ratio; Predictive Value of Tests; Radiology; Retrospective Studies; Risk Factors; Stroke; Tomography; Tomography, X-Ray Computed; Ultrasound; Veins & arteries; Netherlands; Carotid stenosis; Vascular calcification; Intracranial atherosclerosis; Internal carotid artery; Atherosclerosis
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s00330-012-2766-x

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 stenosis ≥ 50  % is unlikely in stroke patients without siphon calcification . • Carotid siphon calcium is a poor indicator of significant carotid artery stenosis .