Contrast-enhanced ultrasound imaging of intraplaque neovascularization in carotid arteries: correlation with histology and plaque echogenicity

Objectives This study was designed to evaluate contrast-enhanced ultrasound imaging of carotid atherosclerosis as a clinicaltool to study intraplaque neovascularization.Background Plaque neovascularization is associated with plaque vulnerability and symptomatic disease; therefore, imagingof neovascularization in carotid atherosclerosis may represent a useful tool for clinical risk stratification andmonitoring the efficacy of antiatherosclerotic therapies.Methods Thirty-two patients with 52 carotid plaques were studied by standard and contrast-enhanced ultrasound imaging.In 17 of these patients who underwent endarterectomy, the surgical specimen was available for histological determinationof microvessel density by CD31/CD34 double staining. Plaque echogenicity and degree of stenosisat standard ultrasound imaging were evaluated for each lesion. Contrast-agent enhancement within the plaquewas categorized as absent/peripheral (grade 1) and extensive/internal (grade 2).Results In the surgical subgroup, plaques with higher contrast-agent enhancement showed a greater neovascularizationat histology (grade 2 vs. grade 1 contrast-agent enhancement: median vasa vasorum density: 3.24/mm2 vs.1.82/mm2, respectively, p 0.005). In the whole series of 52 lesions, echolucent plaques showed a higher degreeof contrast-agent enhancement (p 0.001). Stenosis degree was not associated with neovascularization athistology or with the grade of contrast-agent enhancement.Conclusions Carotid plaque contrast-agent enhancement with sonographic agents correlates with histological density ofneovessels and is associated with plaque echolucency, a well-accepted marker of high risk lesions, but it is unrelatedto the degree of stenosis. Contrast-enhanced carotid ultrasound imaging may provide valuable informationfor plaque risk stratification and for assessing the response to antiatherosclerotic therapies, beyond that providedby standard ultrasound imaging. (J Am Coll Cardiol 2008;52:223–30) © 2008 by the American Collegeof Cardiology Foundation