1. Determine if daily aspirin intake (for three months) would obliterate/reduce ferumoxytol-enhanced MRI signal changes generated by macrophages in cerebral aneurysm wall. Fifteen patients with cerebral aneurysms > 7 mm will be selected to enroll in this pilot study. 10 patients will be imaged at base line with ferumoxytol-enhanced MRI. Following that, they will take aspirin 81 mg daily and then re-imaged again at three months. This group will be compared to a control group of 5 patients where they will have the imagings studies performed at base line and at three months but will NOT take aspirin.