Microembolisation identified on diffusion-weighted magnetic resonance imaging (DW-MRI) is recognized as an important outcome measure for carotid revascularization procedures such as carotid stenting (CAS) or carotid endarterectomy (CEA). In fact, cerebral microembolisation occurring during revascularization procedures is associated with an increased risk of peri- and post-procedural stroke, transient ischemic attack as well as neurocognitive decline. Carotid artery stenting is a less invasive alternative to endarterectomy to treat symptomatic or asymptomatic carotid stenosis. Large randomized clinical trials showed a higher periprocedural risk of non-disabling stroke with CAS and a higher periprocedural risk of myocardial infarction, cranial nerve palsy, and access site hematoma with CEA.

However little is known regarding the correlation between the morphological characteristics of the carotid plaque and the occurrence of microembolisation during the procedure and between microembolisation and midterm cognitive impairment. A few studies suggest that plaque morphology may be an important determinant for the increased risk of microembolisation. These studies however have mainly investigated microembolisation occurring during CAS and exploratory studies comparing the two procedures are still lacking.

The purpose of the present study is to determine the correlation between the morphological characteristics of the carotid plaque and cerebral microembolisation either after carotid stenting or after carotid endarterectomy in patients with symptomatic or asymptomatic carotid disease.

Inclusion Criteria:

• Patients presenting a symptomatic (ipsilateral ischemic stroke, TIA located in the carotid artery territory or retinal ischemia) carotid stenosis between 50% and 99% (according to NASCET and ECST criteria)
• Patients presenting an asymptomatic carotid stenosis between 60% and 99% (according to NASCET and ECST criteria) Patients who accept the informed consent

Exclusion Criteria:

• Important neurological deficit with NIHSS >7 (or severe aphasia) at time of inclusion

• Previous known cognitive impairment

• Pregnancy

• Presence of contraindication based on ground of multidisciplinary team decision:

  • For surgery:

High bifurcation Intracranial extension of the carotid stenosis Patients with tandem lesions High suspicion of severe siphon stenosis Patients with previous irradiation of the cervical region Patients with restenosis after endarterectomy

• For stenting; Excessive arch vessel or carotid artery tortuosity and in particular presence tortuosity ≤90 degrees in the cervical segment Excessive aortic arch plaque burden Patients older than 70 years Unfavourable anatomic disposition as described above Co-morbidities that may preclude the use of a periprocedural dual antiplatelet regime.
• For CT-scan Iodine allergy Renal insufficiency
• For MRI Pacemaker Any other metallic implants Claustrophobia
• For ultrasound Bad quality ultrasound (patient morphology or equipments

Screening of a carotid plaque is part of a routine procedure for patients admitted for stroke or TIA and includes ultrasound, CT-scan and MRI. Patients presenting a symptomatic or asymptomatic carotid stenosis are routinely discussed within a multidisciplinary meeting and the most appropriate therapeutic option is decided. For some patients, surgery and stenting are equivalent options. In that case, the patient may be a candidate for the present study