Crescent Sign Following Enterprise-Stent assisted Coil Embolization of Distal Internal Carotid Artery Aneurysms

We aimed to determine the “significant crescent signs” associated with delayed thromboembolic events (DTE) after changes in antiplatelet medication and to evaluate their incidence and natural course. Methods Between April 2009 and April 2011, 105 consecutive patients underwent stent-assisted coil embolization for unruptured intracranial aneurysms (n=107) in a single tertiary hospital. Sixty-three cases fulfilled the inclusion criteria and were included in this study. Crescent sign was evaluated through follow-up magnetic resonance angiography (MRA) immediately (<48 hours), 6 to 12 months, 1 to 2 years, and 2 to 4 years and correlated with the occurrence of DTE. Results Crescent signs were identified in 26 (41.3%) of 63 cases on immediate follow-up MRA. During the mean radiological follow-up of 53 months, the crescent signs (larger than 5 mm in length) persisted for more than 1 year in 11 (42.3%) of 26 cases. The crescent signs on follow-up MRA showed decreased size in 10 of 26 cases and disappeared in 5 cases. DTE occurred in 6 (9.5%) of 63 cases. In these 6 cases, all DTE occurred when the antiplatelet regimen was changed or stopped. Five of these six cases exhibited a crescent sign measuring over 5 mm in length, at the time of stroke. Conclusions Crescent signs may be associated with DTE. When crescent signs are larger than 5 mm in length and continuously identified on follow-up MRA, continued dual antiplatelet treatment is required.