CT in Nontraumatic Acute Thoracic Aortic Disease: Typical and Atypical Features and Complications

Abstract

Thoracic aortic dissection is the most frequent cause of aortic emergency, and unless it is rapidly diagnosed and treated, the result is death. Helical computed tomography (CT) permits the diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. This imaging modality also enables differentiation between proximal aortic dissection (type A in the Stanford classification) and distal aortic dissection (Stanford type B), which are treated differently and have different prognoses. In 70% of patients in whom nontraumatic acute thoracic aortic dissection is diagnosed after evaluation with helical CT, scans show the typical signs of aortic dissection, with rupture and displacement of the intima. CT also can depict other pathologic entities with similar clinical manifestations, such as intramural hematoma and penetrating atherosclerotic ulcer. Awareness of the different radiologic appearances of these disease entities is essential for differential diagnosis. More than one-third of patients with aortic dissection show signs and symptoms indicative of systemic involvement. Because branch-vessel involvement may increase morbidity and mortality, in this group of patients it is important to evaluate the entire aorta so as to determine the distal extent of the dissection and detect any systemic involvement.

Type A aortic dissection presenting as superior vena cava syndrome

“…4 Aortic dissection results from an intimal tear that allows blood to divide the medial layer, resulting in a true and a false lumen. 8 In 70% of cases, these two lumens are separated by an intimal flap. 9 The Stanford classification, which is most commonly used, is based on involvement of the ascending aorta.…”

Úlcera penetrante de aorta ascendente en un paciente asintomático

“…La UPA se localiza con mayor frecuencia en la porción media y distal de la aorta torácica descendente (90%). Algunos autores lo atribuyen al efecto protector que proporciona el mayor flujo existente en la porción proximal de la aorta, evitando la formación de placas de ateroma 16 . En aorta ascendente, la UPA es menos frecuente (10%), presentando incluso un peor pronóstico que la disección de aorta 4,17 .…”

“…En general, la indicación quirúrgica en las enfermedades agudas de la aorta está condicionada por la localización de la úlce-ra, hematoma o disección 1 . De este modo, está bien establecido que las disecciones localizadas en la aorta ascendente tienen indicación quirúrgica emergente por el riesgo de rotura 14,16 . Existe mayor controversia en relación con el tratamiento de la UPA, y se ha sugerido que la distinción entre úlcera ascendente y descendente también es necesaria para determinar el procedimiento terapéutico más adecuado 1 .…”

“…Si la UPA es ascendente, se recomienda cirugía de sustitución de la porción afectada de la aorta, mientras que si es descendente, el abordaje puede ser endovascular, siempre que no se presenten síntomas de progreso. La inestabilidad hemodinámica, persistencia o recurrencia del dolor, ruptura aórtica, embolismo distal, taponamiento cardíaco y aumento rápido del diámetro aórtico, entre otras 16 , indicarían un abordaje quirúrgico, independientemente de la localización. El abordaje endovascular en la aorta ascendente puede ser un procedimiento demasiado arriesgado 8 .…”

Acute aorta, overview of acute CT findings and endovascular treatment options

“…It is necessary to evaluate a potential compromise of aortic branches, which can cause malperfusion syndrome. Occlusion of aortic branch vessels can be static or dynamic 16 . In a static obstruction the intimal flap enters the artery origin without re-entry and occludes the artery.…”