Spontaneous Echo Contrast Observed on Carotid Duplex Ultrasonography

Spontaneous echo contrast is a swirling, smoke-like echographic pattern observed in B-mode ultrasound imaging, typically arising in areas of blood stasis or low-flow states.This hemodynamic disturbance generates low shear stress due to sluggish flow, leading to endothelial dysfunction and facilitating the activation of fibrinogen, a coagulation factor.Consequently, blood cells, including erythrocytes, readily aggregate, forming a spontaneous echo contrast, a precursor to thrombus formation.Spontaneous echo contrast is primarily found in the left atrium of patients with left atrial enlargement or the left atrial appendage of patients with atrial fibrillation.While less common, it can also be observed in the carotid arteries.This case report presents the imaging findings of spontaneous echo contrast detected during carotid duplex ultrasonography in a patient with metastatic cancer and discusses its clinical implications.