Background and Purpose—We sought to determine the frequency and clinical course of patients with acute ischemic stroke or transient ischemic attack (TIA) who had intracranial nonocclusive thrombus (iNOT) on CT angiography (CTA).

Methods—We retrospectively (June 2002–March 2007) reviewed consecutive patients with acute ischemic stroke or TIA who had CTA performed acutely for diagnostic work-up. A neuroradiologist reviewed all cases with potential iNOT. Criteria to diagnose iNOT rather than occlusive thrombus or atherosclerotic stenosis were: (1) residual lumen present and eccentric; (2) nontapering thrombus; (3) smooth and well-defined thrombus margins; and (4) absence of vessel wall calcification. We defined functional independence at discharge as modified Rankin scale score 2.

Results—Of 865 patients, 23 (2.7%) exhibited iNOT on CTA (43% women, mean age 69±14 years, median National Institute of Health Stroke Scale score 3 [range, 0–23]; median onset-to-CTA time 3.5 hours [range, 0.9–75]). Four patients (17%) deteriorated clinically during the hospital course and had persistent new focal neurological deficits. All of them were functionally dependent at discharge. All 19 patients (83%) without persistent clinical deterioration (2 patients had recurrent TIAs) were functionally independent at discharge.

Conclusion—Intracranial nonocclusive thrombus on CTA is relatively uncommon. The majority of patients have a good clinical outcome. However, some patients deteriorate clinically and are functionally dependent at discharge.