Free-floating thrombus of internal carotid artery presenting as thromboembolism

A 61-year-old man presented with left lower limb weakness for 2 days. He had a history of coronary artery disease and took aspirin with atorvastatin daily. Magnetic resonance imaging of the brain demonstrated multiple patchy foci of acute infarction in right frontal and parietal lobes. Computed tomography angiography revealed the donut sign, representing a thrombus as a filling defect surrounded by contrast (A). 1 Menon B.K. Singh J. Al-Khataami A. Demchuk A.M. Goyal M. The donut sign on CT angiography: an indicator of reversible intraluminal carotid thrombus?. Neuroradiology. 2010; 52: 1055-1056 Crossref PubMed Scopus (34) Google Scholar A long, string-like protrusion of right internal carotid artery (ICA) indicated a free-floating thrombus (FFT) (A). 2 Torres C. Lum C. Puac-Polanco P. Shamy M. Blacquiere D. Lun R. et al. Differentiating carotid free-floating thrombus from atheromatous plaque using intraluminal filling defect length on CTA: a validation study. Neurology. 2021; 97: e785-e793 Crossref PubMed Scopus (4) Google Scholar Ultrasound examination of the carotid artery showed the thrombus was floating (A, Video). The right ICA three-dimensional reconstruction showed the stenosis position, structure of plaque and thrombus (B/Cover).