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(Stroke. 2008;39:2011.)
© 2008 American Heart Association, Inc.

Original Contributions

Hyperdense Internal Carotid Artery Sign

A CT Sign of Acute Ischemia

Ozcan Ozdemir, MD; Andrew Leung, MD, FRCP; Miguel Bussiére, MD, FRCP; Vladimir Hachinski, MD, FRCP, DSc David Pelz, MD, FRCP

From the Department of Neurological Sciences (O.O., V.H.), the Department of Diagnostic Radiology and Nuclear Medicine (A.L., D.M.P.), and the Department of Clinical Neurological Sciences, Department of Diagnostic Radiology and Nuclear Medicine (B.M.), London Health Science Centre, University of Western Ontario, London, ON.

Correspondence to Ozcan Ozdemir, MD, Department of Clinical Neurological Sciences, University of Western Ontario, London Health Sciences, University Campus, London, Ontario, Canada. Postal Address: 339 Windermere Road, Room: A7-030 London ON Canada N6A5A5. E-mail ozcan_99{at}yahoo.com

Background and Purpose— The hyperdense middle cerebral artery sign (HMCAS) is a well-established marker of early ischemia on noncontrast computed tomography of the brain (NCCT). Recently the MCA dot sign has been described and proposed to indicate thrombosis of the M2 or M3 middle cerebral artery branches. The purpose of this study was to define the hyperdense ICA sign (HICAS) and determine its prevalence, diagnostic and prognostic value, and its reliability as a marker for ischemia.

Methods— Noncontrast computed tomography scans of 71 patients with acute ischemic stroke were analyzed for the presence of a HICAS, HMCAS, or MCA dot sign. For the validation of HICA and HMCA signs on NCCT, 32 of 71 patients who underwent gold standard CT angiography (CTA) before thrombolytic therapy were included in the analysis. The presence of a HICAS was correlated with initial neurological severity and the short and long-term outcomes.

Results— A HICAS was found in 24% of patients on NCCT. In patients with a HICAS, mean age was 63±17.4 and mean time from symptom onset to CT was 103 minutes. Interobserver agreement was excellent for the HICAS. The HICAS has high specificity (100%) and positive predictive value (100%) in predicting the presence of distal internal carotid artery thrombus on CTA. Patients with a HICAS had a more severe initial neurological deficit and worse prognosis than patients without a HICAS.

Conclusion— The HICAS is a reliable and a highly specific marker of thromboembolic occlusion of the distal ICA and is associated with severe initial neurological deficit and worse outcome despite thrombolytic therapy.

Key Words: internal carotid artery • acute ischemic stroke • computed tomography