Aneurysm and type B dissections account for most acute abdominal aortic abnormalities. The postsurgical aorta deserves special attention owing to the risk of complications. Most aortic abnormalities presenting acutely are emergencies that carry a high risk of mortality, and imaging plays a critical role in patient evaluation. Modern helical CT scanners provide excellent spatial resolution, are readily available, and allow for rapid imaging. For these reasons, helical CT angiography is the imaging modality of choice for initial evaluation of the acute aorta.