Dose-Finding, Feasibility Study of Optison in Contrast Enhanced U/S for the Detection of Carotid Artery Disease

Inclusion Criteria: * The subject is is greater than or equal to 18 years of age. * The subjects has highly suspected or established carotid artery disease. * The subject has undergone or been referred for either unilateral or bilateral intra-arterial X-ray carotid angiography for the determination of subject management (within 30 days before or after the U/S procedure). * The subject has non-diagnostic U/S of the carotids as defined by institutional standards. Exclusion Criteria: * The subject presents any clinically active, serious, life-threatening disease, with a life expectancy of less than 1 month or where study participation may compromise the management of the subject or other reason that in the judgment of the investigator makes the subject unsuitable for participation in the study. * The subject has a history of acute occlusion requiring medical intervention of any artery (including aorta) within 6 months of consent. * The subject has a known or suspected hypersensitivity to any of the components of Optison, blood, blood products, or albumin. * The subject has right to left, bi-directional or transient right to left cardiac shunts.