Swirling of microbubbles: Demonstration of a new finding of carotid plaque ulceration on contrast-enhanced ultrasound explaining the arterio-arterial embolism mechanism.

Carotid plaque ulceration is a well-established feature of vulnerability, associated with high risk for neurological symptoms. From a pathogenetic point of view, the mechanism responsible for occurrence of symptomatology relies on the aggregation of platelets within the ulcer cavity, activation of coagulation mechanism, formation of thrombus and arterio-arterial embolization of thrombotic material in the central nervous system. Many imaging modalities including unenhanced ultrasound, computed tomographic angiography and magnetic resonance angiography have been used to image and diagnose carotid plaque ulceration with varying success. Contrast-enhanced ultrasound has been recently introduced in the study of carotid disease offering improved flow visualization and better plaque surface delineation. We present a case where contrast-enhanced ultrasound visualized the swirling pattern of movement of the microbubbles within the ulcer cavity. These findings illustrate the underlying hemodynamic mechanism of arterio-arterial embolization and can be proposed as a new finding of plaque ulcerations on contrast-enhanced ultrasound.