Name : Ali
Affiliation : Oakland University William Beaumont School of Medicine, University of California at Irvine and Wayne State University
Academic Degree: Professor of Radiology
Gender : Male
Age : 46
46 year old male with chest pain
Imaging Procedures and Findings
Axial CT scan (combined images 1-2) through the thorax shows dissection flap involvement of the aortic root, origin of right brachiocepahalic artery and descending aorta. Axial CT scan through the abdomen (image 3) reveals that intimal flap extends into abdominal aorta at the level of renal arteries. However, both kidneys demonstrate normal and symmetrical perfusion. Since the dissection flap involves the ascending thoracic aorta, it is classified as Stanford type A. Image 4 illustrates drawings of different types of aortic dissection. Unenhanced axial image (image 5) in a different patient shows intimal calcifications in a curvilinear configuration in descending aorta accompanied by crescent-shaped aortic wall hyper attenuation. Black arrows show the intimal border in both ascending and descending aorta. Also noted are pleural hematoma and hemopericardium (white arrowheads). Contrast??enhanced axial image (image 6) depicts a smooth, nonenhancing crescentic region of aortic wall thickening (black arrows) consistent with intramural hematoma.
Aortic dissection is the most common acute emergency condition of the aorta and has a potential of a fatal outcome. Outcome is determined by the type and extent of dissection and the presence of associated complications (eg, cerebral sequelae, aortic branch involvement, pericardial involvement, and visceral involvement), with early diagnosis and treatment being essential for improved prognosis. Aortic dissections are classified on the basis of the site of the intimal tear according to the Stanford classification system. Type A aortic dissection involves the ascending thoracic aorta and may extend into the descending aorta, whereas in a type B dissection the intimal tear is located distal to the left subclavian artery. Type A dissection typically requires urgent surgical intervention, whereas type B dissection can often be treated medically. An intramural hematoma results from rupture of the vasa vasorum and hemorrhage into the arterial media, which leads to weakening of the aortic wall. The distinguishing feature of this entity is an absence of the intimal disruption that characterizes classic aortic dissection. On unenhanced axial CT images, a crescentic, eccentric, hyperattenuating region of thickening of the aortic wall (diameter, >7 mm; attenuation, 60??70 HU) is considered diagnostic of acute intramural hematoma, in contrast to the multilayered pattern of increasing attenuation seen in aortic dissection, in which there is partial or complete thrombosis of the false lumen. The natural history of an intramural hematoma may include periods of stabilization, regression, and resolution or may consist of continuous disease progression. Potential complications include progression to overt aortic dissection, development of ulcer like projections of the aorta, and formation of an aortic aneurysm. Routine follow-up imaging is necessary even if a hematoma decreases in size or completely resolves, because an ulcer like projection, aneurysm, or aortic dissection may still develop at the site.
Type A Aortic dissection
1. McMahon MA, Squirrell CA. Multidetector CT of Aortic Dissection: A Pictorial Review. RadioGraphics. 2010; 30:445-460.
2. Chao CP, Walker TG, Kalva SP. Natural History and CT Appearances of Aortic Intramural Hematoma. RadioGraphics. 2009; 29:791-804.