Objective: To explore the association between spatio-temporal blood flow velocities (peak systole and end-diastole at prior-stenosis, at maximum stenosis, and post-stenosis) and carotid plaque vulnerability defined by histology staining. Secondary, to assess the association between ultrasound elastography and carotid plaque vulnerability defined by histology staining. Furthermore, to assess the association between blood flow-derived parameters, including wall shear stress (WSS), vector complexity and vorticity, and plaque vulnerability. To evaluate the hemodynamic consequences of a CEA. Last, to explore whether the presence of circulating biomarkers is related to the degree of plaque vulnerability (as reflected by histology and/or ultrasound).

Study design: A multicentre, prospective, observational, cohort study in a total of 70 patients.

Study population: Patients with a carotid artery stenosis ≥50% according to clinically performed imaging (i.e. duplex, computed tomography angiography (CTA), or magnetic resonance angiography (MRA)) that are scheduled for a CEA.

Intervention (observational): A carotid ultrasound with flow and elastography (strain and shear wave) measurements will be performed maximally 2 weeks prior to the CEA. In the first 20 included patients in the Radboudumc, a 10 mL blood sample will be collected during surgery via the arterial line that is applied for regular care. The plaque excised during CEA will be histologically examined to assess the plaque composition, and therefore plaque vulnerability. Ultrasound-based flow imaging will be repeated six weeks after the CEA to assess the hemodynamic consequences of the CEA procedure. Besides, clinical parameters will be subtracted from electronic health record or, if missing, anamnestically collected from the patient.

Main study parameters/endpoints: Association between 2D spatio-temporal blood flow velocities (peak systole and end-diastole at prior-stenosis, maximum stenosis and post-stenosis), measured by ultrafast ultrasound measurements, and plaque vulnerability (stable versus unstable), defined by histology staining.

Inclusion Criteria:

• Presence of carotid artery stenosis (≥50%) according to conventional clinically performed imaging (duplex/CT(A)/MR(A)) and scheduled for a CEA;
• Possibility to perform carotid ultrasound ≤2 weeks before the CEA
• ≥18 years old;
• Able to provide signed or oral informed consent.

Exclusion Criteria:

• Hampered carotid blood flow imaging during clinically performed duplex/doppler measurements due to near to total carotid occlusion at the side of interest or a calcified plaque;
• Restenosis after carotid revascularisation at side of interest;
• Participating in another clinical study, interfering on outcomes;

Patients with a carotid artery stenosis ≥50% according to clinically performed imaging (i.e. duplex, computed tomography angiography (CTA), or magnetic resonance angiography (MRA)) that are scheduled for a CEA.