The purpose of this study is to evaluate the ability of contrast enhanced carotid ultrasound to serve as an indicator of disease activity in patients with Takayasu's arteritis or Giant Cell arteritis and to determine if patients with active arteritis have a thickening of their blood vessel walls compared to healthy people of the same age and gender.

Takayasu's arteritis and Giant Cell arteritis are chronic, relapsing diseases of the large arteries which can lead to significant narrowing of the arteries through episodes of inflammation within the artery walls. The changes in the vessel walls will be determined by an ultrasound test looking at and measuring: carotid vessel wall changes called carotid Intimal-Media Thickness (cIMT) and the presence of new blood vessels (neovascularization) using a contrast agent. Ultrasound findings will be correlated with markers of inflammation in the blood, findings from other radiology studies (such as MRI) already ordered as part of routine clinical care, and physical exam findings and symptoms of consistent with disease activity. 15 arteritis patients and 5 healthy controls will be recruited.

Inclusion Criteria:

• Male and female patients >18 years
• Diagnosis of Takayasu's arteritis or giant cell arteritis
• Suspicion of common carotid involvement on the basis of physical examination (cervical bruit), carotidynia, documented CCA involvement on an imaging study (MRA, CTA, or ultrasound), or documented upper extremity large vessel involvement on an imaging study (MRA or CTA or ultrasound).
• Ability to provide informed consent

Exclusion Criteria:

• Prior stroke, carotid surgery or angioplasty
• Pregnant (or trying to become pregnant)
• Nursing
• Known or suspected cardiac shunt
• Documented hypersensitivity to the contrast agent
• Severe pulmonary hypertension or unstable cardiopulmonary conditions (acute myocardial infarction, acute coronary artery syndromes, worsening or unstable congestive heart failure, serious ventricular arrhythmias, or respiratory failure)

Patients with Takayasu's arteritis or giant cell arteritis will be screened from the clinics of the Vasculitis Clinic and the Vascular Medicine Clinic at the Cleveland Clinic.