Ultrasound and Other Images of Artery Blockages

Contrast-Enhanced Ultrasound Imaging of Carotid Plaque Neovascularization

Background:

- Treatments for partly blocked carotid arteries are determined by a person s symptoms and by tests that show how severe the blockage is. Studies show that the material that blocks an artery is more important in spotting future problems than how tight the blockage is. Researchers want to develop better imaging studies to find which blockages are more high-risk.

Objectives:

- To use imaging studies to look at high-risk carotid artery blockages.

Eligibility:

- Individuals at least 21 years of age whose ultrasound exams show a major carotid artery blockage.

Design:

• Participants will be screened with a medical history, physical exam, blood and urine tests, , an ultrasound scan and a magnetic resonance imaging (MRI) scan.
• Participants will have ultrasound and other scans to obtain pictures of the arteries. The scans will use drugs that may help study doctors get a better picture of the blood vessels and blockages.
• Participants will have followup phone calls yearly for 3 years. If a participant later has surgery to remove the blockage, the surgeon will save part of it for future study.

Traditional evaluations of atherosclerotic disease in the carotid arteries and treatment recommendations have focused primarily on degree of obstruction. Emerging data from histologic series and advanced imaging studies suggests that anatomic features related to plaque biology, including inflammation, lipid accumulation, and angiogenesis, may be used to detect vulnerable plaques more likely to cause clinical effects. Contrast-enhanced ultrasound (CEUS) is a new technique that uniquely visualizes intraplaque neovascularization. Magnetic resonance imaging (MRI) of carotid plaque lipid core and intraplaque hemorrhage has shown value in the prediction of future neurologic events. We propose a multimodal approach to assess plaque activity in subjects with known carotid disease using CEUS, MRI imaging, and serum biomarker evaluation. In subjects undergoing carotid endarterectomy, imaging findings will be validated by histology. Both imaging and histologic findings will be compared with prospective cardiovascular events.

• INCLUSION CRITERIA:

Inclusion Criteria for Group A:

• Adult subjects age greater than or equal to 21 years
• Able to give written informed consent
• Prior clinical ultrasound exam showing a carotid stenosis of greater than or equal to 50 percent

Inclusion Criteria for Group B:

• Adult subjects age greater than or equal to 21 years
• Able to give written informed consent
• Prior clinical ultrasound exam showing a carotid stenosis suspected of causing symptoms and/or clinical recommendation to undergo carotid endarterectomy

EXCLUSION CRITERIA:

• Atrial fibrillation or other irregular rhythm that would preclude adequate image acquisition
• Subjects with a contraindication for the ultrasound contrast agent.
• Subjects with pacemakers, defibrillators, cerebral aneurysm clips, neural stimulators, ear implants or other clinical contra-indications for magnetic resonance scanning will be excluded from the MRI portion of the study.
• Subjects with an estimated glomerular filtration rate [eGFR] less than 30 ml/min/1.73 m(2) body surface area will be excluded from the contrast MRI portion of the study but will still undergo non-contrast imaging.
• The eGFR will be used to estimate renal function if reported by the laboratory. Otherwise, estimated glomerular filtration rate (eGFR) can be based on the Modification of Diet in Renal Disease (MDRD) study equation (see below) in subjects with stable renal function. This formula is not applicable to subjects with acute renal insufficiency: eGFR (ml/min/1.73 m(2)) equal to 175 times (serum creatinine)-1.154 times (age)-0.203 times 0.742 (if the subject is female) times 1.212 (if the subject is black).
• Pregnant or lactating women