Patients are usually referred for noninvasive studies when either a carotid bruit is auscultated by chance, or when a symptom is the presenting feature. As described herein, FMD lesions tend to be higher in the extracranial segment of the ICA than atherosclerotic lesions, and they may not be readily demonstrated by duplex scan. However, with an experienced technician and a high level of suspicion, we feel the diagnosis may be established by this approach. Doppler examination will demonstrate minimal disease in the carotid bulb, with hemodynamically significant lesions occurring in the intermediate and distal segments of the ICA.5 Tandem and perhaps multiple lesions may be present, due to multifocal thickening and alternating areas of thin and dilated wall. Thickening hyperechoic shadowing may be present, suggesting hyperplasia of the arterial wall. In addition, redundancy and kinking of the extracranial ICA may be present. If FMD is suspected on a screening ultrasound, angiographic studies should be performed. The contrast study should include an aortic arch study, carotid injections, intracranial artery views, and visualization of the renal and external iliac arteries.