This will be a pilot study of 9 patients undergoing standard-of-care clinically indicated carotid endarterectomy. The nine patients will receive an injection of Indocyanine green (ICG) at a dose of 0.25 mg/kg (maximum 25 mg) as an intravenous bolus.

Immediately following endarterectomy, the resected specimen will be immersed in normal saline. Ex vivo fluorescence reflectance imaging (FRI) and immunohistochemistry will be performed.

The investigators hypothesize that compared to controls, ICG-injected patients will demonstrate increased ex vivo and microscopic ICG fluorescence signal within areas of plaque.

Inclusion Criteria:

• Consecutive patients scheduled for elective carotid endarterectomy at Massachusetts General Hospital
• Age > 18 years of age.
• Signed informed consent.

Exclusion criteria:

• Hemodynamic instability
• Any history of iodide allergy
• Any history of renal failure (estimated Glomerular Filtration Rate (eGFR) <50 ml/min/1.73 m2)
• Any history of liver failure
• Any history of bleeding diathesis
• Any history of cerebral vascular accident in the preceding 3 months
• Pregnant or lactating females.
• Hx of seafood allergy