NIH CCR2 AAA Study

Inclusion Criteria: * 40 years old and above * With or without active tobacco use * Asymptomatic patients with known AAAs by CT angiogram (men ≥ 5.5 cm, women ≥ 5.0cm). * Non-AAA volunteers will have a documented absence of AAA by exam and recent screening ultrasound (US). * Able to comprehend and willing to follow instructions for the study procedures as called for by the protocol Exclusion Criteria: * Inability to receive and sign informed consent. * Patients with Stage ≥ 4 chronic renal failure (calculated by modification of diet in renal disease eGFR equation \[to minimize confounding imaging variables\]) * Documented allergy to iodinated contrast and/or shellfish. * Patients with an unstable clinical condition that in the opinion of the principal investigators or designee precludes participation in the study. * Inability to tolerate 60 minutes in a supine position with arms down at sides, as necessary for PET/CT. * Positive pregnancy test or lactating. * Other conditions such as symptomatic/recently treated coronary disease, cancer requiring oncologic management, or autoimmune/inflammatory diseases (e.g., rheumatoid arthritis or multiple sclerosis) that are known to have increased associated CCR2 expression. * Non-AAA volunteers may not carry a diagnosis of aortoiliac occlusive disease, as documented by their treating vascular surgeon, as significantly progressed atherosclerotic disease may demonstrate exaggerated, associated CCR2 expression.