Contrast Enhanced Ultrasound: Visualization of Far Field and Classification of Plaque in the Extracranial Carotid Arteries

Abstract

Ultrasound stratification for the degree of carotid artery disease based solely on lumen reduction has poorly predicted patient outcomes. This pilot study focused on patients with moderate carotid artery stenosis. Our purpose was to use contrast imaging with ultrasound to improve carotid field. A total of 10 patients diagnosed with moderate carotid artery stenosis were rescanned with an administration of a contrast imaging agent. Two-dimensional (2D) imaging, color, and Doppler were utilized to scan the patients. The 20 carotid arteries were blindly read by 2 experienced physicians. Visualization of far field, quality of Doppler envelope, plaque morphology, and overall image quality were semi-quantifiably assessed. With the use of a contrast imaging agent, there was a reduction in interphysician interpretation variability. The Kappa coefficient yielded an increase in agreement for postcontrast imaging in the majority of variables. The Doppler envelope showed improvement from precontrast (0.06) to postcontrast (0.63). The visualization of the far fields demonstrated a significant increase in agreement (0.77, 0.71, and 0.67) postcontrast. Plaque morphology demonstrated enhancement in characterization with contrast (–0.09 to 0.66). In this study, contrast-enhanced ultrasound (CEUS) was found to increase overall image quality. Improved interpretation can enhance risk stratification and with further exploration could be used to guide treatment plans for patients with asymptomatic moderate carotid artery disease.