Carotid artery string sign
Severe narrowing of the ICA such that only a small amount of residual flow is seen along the almost completely occluded (>95% stenosis) artery lumen is referred to as the “string” sign. Such a high-grade ICA stenosis needs to be distinguished from a completely occluded ICA because a patient with a high-grade stenosis is still a surgical candidate for endarterectomy, whereas a patient with complete ICA occlusion is not an endarterectomy candidate. Strict attention to sonographic technique is required so as not to mistake subtotal ICA occlusion with slow flow from complete ICA occlusion.
