Technical Innovation Protocol for MR & US Plaque Imaging: Reproducibility.

The population will consist of patients with carotid artery plaques that cause 30% to 70% lumen stenosis. The degree of stenosis will be assessed by the peak systolic velocity end end diastolic velocity near the stenosis measured by ultrasound duplex.

The researchers choose to investigate patients with 30% to 70% carotid artery stenosis for the following reasons: 1. Treatment of patients with carotid artery plaques is based on the amount of lumen stenosis. A stenosis of more than 70% is generally treated surgically by endarterectomy. Doing repeated measurements is only possible in patients not treated surgically. 2. Patients with 30% to 70% carotid artery stenosis are, despite their drug treatment, still at high risk for cardiovascular events.

Inclusion Criteria:

• Patients, with 30 to 70% carotid artery stenosis on ultrasound duplex, who will not go for endarterectomy.

Exclusion Criteria:

• Metal in the body, as a result of e.g. pacemaker or artificial cardiac valves; claustrophobia; surgery performed in the area of measurement (Carotid artery region); Cardiac arrhythmias.