[Computed tomography in the evaluation of acute aortic dissection]

Acute aortic dissection is the most frequent cause of aortic emergency, associated to high morbidity and mortality rates. It is important to quickly establish the diagnosis and properly characterize the findings in order to determine the appropriate treatment. Multidetector computed tomography is, in many centers, the initial imaging modality of choice, due to its diagnostic accuracy (with sensitivity and specificity indexes of nearly 100%), wide availability, examination speed and ease performance. It enables differentiation between classic aortic dissection, intramural hematoma and penetrating atherosclerotic ulcer, entities with a similar clinical presentation. Initial precontrast images are extremely important in the detection of an intramural hematoma. Regarding classic aortic dissection, the definitive diagnostic finding is the demonstration of two contrast-filled lumina separated by an intimal flap. Accurate differentiation between the true and the false lumen is often possible and has becoming particularly important for treatment planning.