Prospective Contrast Ultrasound imaging of patients with AAA as part of a pilot feasibility study to predict AAA growth and test gender differences in rate of growth and rupture. CUS findings will be correlated with serum biomarkers and AAA wall histology. Potential significance: This study will evaluate the AAA wall and will be based on detecting areas of increased vasa vasorum density within the aneurysm wall and intraluminal thrombus, which indicate regional ischemia and inflammation of the aortic wall and propensity for weakening, enlargement or rupture. This novel evaluation of the aortic wall in patients with AAA will allow individualized treatment based on the biological potential for growth and rupture.