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CT in Nontraumatic Acute Thoracic Aortic Disease: Typical and Atypical Features and Complications¹

¹ From the Departments of Radiology (E.C., M.A., X.G., J.M.M.) and Pathology (M.A.C.), SDI UDIAT-CD, Institut Universitari Parc Taulí-UAB, Corporació Parc Taulí, Parc Taulí s/n, 08208 Sabadell, Spain; and Department of Radiology, Hospital de la Ribera, Alzira, Spain (Y.P.). Recipient of a Certificate of Merit award for an education exhibit at the 2002 RSNA scientific assembly. Received February 7, 2003; revision requested April 16 and received May 27; accepted June 11. Address correspondence to E.C. (e-mail: ecastaner@cspt.es).

View larger version (51K): [in a new window]   Figure 1a.  (a) Diagram of the thoracic aorta shows the ascending segment, transverse segment or arch, and descending segment, which begins distal to the ligamentum arteriosum. On CT scans, the landmark that indicates the beginning of the descending aorta is the left subclavian artery. (b) Drawing shows the Stanford classifications of aortic dissections and the equivalent DeBakey classifications.

View larger version (63K): [in a new window]   Figure 1b.  (a) Diagram of the thoracic aorta shows the ascending segment, transverse segment or arch, and descending segment, which begins distal to the ligamentum arteriosum. On CT scans, the landmark that indicates the beginning of the descending aorta is the left subclavian artery. (b) Drawing shows the Stanford classifications of aortic dissections and the equivalent DeBakey classifications.

View larger version (102K): [in a new window]   Figure 2a.  (a) Schematic of aortic layers in typical aortic dissection shows a tear of the intimal layer, which has resulted in the formation of two lumina (one false, one true). (b) Photograph of an autopsy specimen shows a Stanford type B aortic dissection. An intimal tear (arrows) and intimal calcifications (arrowheads) are clearly visible in the descending aorta.

View larger version (156K): [in a new window]   Figure 2b.  (a) Schematic of aortic layers in typical aortic dissection shows a tear of the intimal layer, which has resulted in the formation of two lumina (one false, one true). (b) Photograph of an autopsy specimen shows a Stanford type B aortic dissection. An intimal tear (arrows) and intimal calcifications (arrowheads) are clearly visible in the descending aorta.

View larger version (80K): [in a new window]   Figure 3a.  Rupture of a Stanford type A typical aortic dissection in an 18-year-old patient with aortic coarctation. (a) Unenhanced CT scan shows an aneurysm and displaced intima in the ascending aorta. The intima (arrow) is hyperattenuated due to severe anemia. (b) Contrast-enhanced CT scan shows the intimal flap (arrowhead) in the ascending aorta, coarctation (*) in the descending aorta, and substantial collateral circulation through bronchial and intercostal arteries (arrows). Mediastinal hemorrhage and bilateral pleural effusions are also evident.

View larger version (86K): [in a new window]   Figure 3b.  Rupture of a Stanford type A typical aortic dissection in an 18-year-old patient with aortic coarctation. (a) Unenhanced CT scan shows an aneurysm and displaced intima in the ascending aorta. The intima (arrow) is hyperattenuated due to severe anemia. (b) Contrast-enhanced CT scan shows the intimal flap (arrowhead) in the ascending aorta, coarctation (*) in the descending aorta, and substantial collateral circulation through bronchial and intercostal arteries (arrows). Mediastinal hemorrhage and bilateral pleural effusions are also evident.

View larger version (83K): [in a new window]   Figure 4a.  Stanford type B typical aortic dissection. (a) Unenhanced CT scan depicts displaced intimal calcifications (arrow) in the descending aorta. (b) Contrast-enhanced CT scan shows an intimal flap (arrow) in the descending aorta.

View larger version (100K): [in a new window]   Figure 4b.  Stanford type B typical aortic dissection. (a) Unenhanced CT scan depicts displaced intimal calcifications (arrow) in the descending aorta. (b) Contrast-enhanced CT scan shows an intimal flap (arrow) in the descending aorta.

View larger version (150K): [in a new window]   Figure 5.  Unenhanced CT scan depicts calcified thrombus (arrow) in the descending aorta, which mimics displaced intimal calcification.

View larger version (84K): [in a new window]   Figure 6a.  Contrast-enhanced CT scans of Stanford type A typical aortic dissection show the intimal flaps (arrows) in the ascending and descending aorta (a) and the aortic arch (b).

View larger version (87K): [in a new window]   Figure 6b.  Contrast-enhanced CT scans of Stanford type A typical aortic dissection show the intimal flaps (arrows) in the ascending and descending aorta (a) and the aortic arch (b).

View larger version (118K): [in a new window]   Figure 7a.  Stanford type B typical aortic dissection. Sequential contrast-enhanced CT scans show a cobweb sign (arrow)—linear traces of low attenuation—in the false lumen. The beak sign (arrowhead) is caused by a wedge-shaped protrusion of the hematoma in the false lumen. A motion artifact can be seen in the ascending aorta. The true lumen (* in b) is compressed and adopts a crescent shape.

View larger version (121K): [in a new window]   Figure 7b.  Stanford type B typical aortic dissection. Sequential contrast-enhanced CT scans show a cobweb sign (arrow)—linear traces of low attenuation—in the false lumen. The beak sign (arrowhead) is caused by a wedge-shaped protrusion of the hematoma in the false lumen. A motion artifact can be seen in the ascending aorta. The true lumen (* in b) is compressed and adopts a crescent shape.

View larger version (105K): [in a new window]   Figure 8a.  Stanford type A typical aortic dissection with intimointimal intussusception. Contrast-enhanced CT scans show the circumference of the intimal intussusception (arrows) in the aortic arch (a) and the intimal flap (arrows) in the aortic root (b). Note the intimal flap in the descending aorta in b.

View larger version (116K): [in a new window]   Figure 8b.  Stanford type A typical aortic dissection with intimointimal intussusception. Contrast-enhanced CT scans show the circumference of the intimal intussusception (arrows) in the aortic arch (a) and the intimal flap (arrows) in the aortic root (b). Note the intimal flap in the descending aorta in b.

View larger version (62K): [in a new window]   Figure 9a.  Mural thrombus. Sequential contrast-enhanced CT scans show an atheromatous thrombus (arrow in a) with an irregular internal border. The thrombus overlies the calcified intima and maintains a constant location in the aorta.

View larger version (65K): [in a new window]   Figure 9b.  Mural thrombus. Sequential contrast-enhanced CT scans show an atheromatous thrombus (arrow in a) with an irregular internal border. The thrombus overlies the calcified intima and maintains a constant location in the aorta.

View larger version (101K): [in a new window]   Figure 10a.  (a) Schematic of aortic layers in IMH shows a hemorrhage within the media but no intimal tear. Red dots inside the media represent the vasa vasorum. (b) Photograph of an autopsy specimen reveals hematoma (*) within the media, between the intima (held in place by a surgical clamp) and the adventitia (arrow). There is no evidence of intimal tear.

View larger version (156K): [in a new window]   Figure 10b.  (a) Schematic of aortic layers in IMH shows a hemorrhage within the media but no intimal tear. Red dots inside the media represent the vasa vasorum. (b) Photograph of an autopsy specimen reveals hematoma (*) within the media, between the intima (held in place by a surgical clamp) and the adventitia (arrow). There is no evidence of intimal tear.

View larger version (84K): [in a new window]   Figure 11a.  Type A IMH. (a) Unenhanced CT scan depicts crescent-shaped areas with high attenuation (arrows) extending along the walls of the ascending and descending aorta. The displaced intimal calcifications in the descending aorta indicate a subintimal location. A pericardial effusion (arrowheads) also is visible. (b) Contrast-enhanced CT scan shows no enhancement of attenuation in the crescent-shaped areas (arrows). IMH is less apparent here than on the unenhanced CT scan in a.

View larger version (78K): [in a new window]   Figure 11b.  Type A IMH. (a) Unenhanced CT scan depicts crescent-shaped areas with high attenuation (arrows) extending along the walls of the ascending and descending aorta. The displaced intimal calcifications in the descending aorta indicate a subintimal location. A pericardial effusion (arrowheads) also is visible. (b) Contrast-enhanced CT scan shows no enhancement of attenuation in the crescent-shaped areas (arrows). IMH is less apparent here than on the unenhanced CT scan in a.

View larger version (97K): [in a new window]   Figure 12.  Unenhanced CT scan shows Stanford type B IMH (arrow) compressing the lumen of the descending aorta, as well as pleural effusion. These findings increase the likelihood of the hematoma progressing to dissection. The faint lines in the ascending aorta are artifacts.

View larger version (99K): [in a new window]   Figure 13a.  Evolution of IMH to typical dissection. (a) Unenhanced CT scan shows a crescent-shaped area of high attenuation in the descending aorta, indicating intimal displacement (arrow). (b) Contrast-enhanced CT scan acquired at the same time as a shows no enhancement of the crescent-shaped area (arrow). (c) Contrast-enhanced CT scan acquired 1 week later because the patient reported persistent pain shows aortic dilatation and dissection of the lumen (arrow).

View larger version (89K): [in a new window]   Figure 13b.  Evolution of IMH to typical dissection. (a) Unenhanced CT scan shows a crescent-shaped area of high attenuation in the descending aorta, indicating intimal displacement (arrow). (b) Contrast-enhanced CT scan acquired at the same time as a shows no enhancement of the crescent-shaped area (arrow). (c) Contrast-enhanced CT scan acquired 1 week later because the patient reported persistent pain shows aortic dilatation and dissection of the lumen (arrow).

View larger version (82K): [in a new window]   Figure 13c.  Evolution of IMH to typical dissection. (a) Unenhanced CT scan shows a crescent-shaped area of high attenuation in the descending aorta, indicating intimal displacement (arrow). (b) Contrast-enhanced CT scan acquired at the same time as a shows no enhancement of the crescent-shaped area (arrow). (c) Contrast-enhanced CT scan acquired 1 week later because the patient reported persistent pain shows aortic dilatation and dissection of the lumen (arrow).

View larger version (105K): [in a new window]   Figure 14a.  (a-d) Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: aortic atheroma (a), benign intimal plaque ulceration contained in the intima (b), medial hematoma with potential adventitial false aneurysm (c), and transmural rupture (d). (e) Photograph of an autopsy specimen shows severe atherosclerotic changes in the descending aorta, with ulceration of the media (arrows) and IMH (*). Scale is in centimeters.

View larger version (103K): [in a new window]   Figure 14b.  (a-d) Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: aortic atheroma (a), benign intimal plaque ulceration contained in the intima (b), medial hematoma with potential adventitial false aneurysm (c), and transmural rupture (d). (e) Photograph of an autopsy specimen shows severe atherosclerotic changes in the descending aorta, with ulceration of the media (arrows) and IMH (*). Scale is in centimeters.

View larger version (93K): [in a new window]   Figure 14c.  (a-d) Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: aortic atheroma (a), benign intimal plaque ulceration contained in the intima (b), medial hematoma with potential adventitial false aneurysm (c), and transmural rupture (d). (e) Photograph of an autopsy specimen shows severe atherosclerotic changes in the descending aorta, with ulceration of the media (arrows) and IMH (*). Scale is in centimeters.

View larger version (102K): [in a new window]   Figure 14d.  (a-d) Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: aortic atheroma (a), benign intimal plaque ulceration contained in the intima (b), medial hematoma with potential adventitial false aneurysm (c), and transmural rupture (d). (e) Photograph of an autopsy specimen shows severe atherosclerotic changes in the descending aorta, with ulceration of the media (arrows) and IMH (*). Scale is in centimeters.

View larger version (122K): [in a new window]   Figure 14e.  (a-d) Diagrams illustrate the four stages in the formation of a penetrating atherosclerotic ulcer: aortic atheroma (a), benign intimal plaque ulceration contained in the intima (b), medial hematoma with potential adventitial false aneurysm (c), and transmural rupture (d). (e) Photograph of an autopsy specimen shows severe atherosclerotic changes in the descending aorta, with ulceration of the media (arrows) and IMH (*). Scale is in centimeters.

View larger version (143K): [in a new window]   Figure 15a.  Saccular aneurysm in the aortic arch caused by a penetrating atherosclerotic ulcer. (a) Unenhanced CT scan shows saccular dilatation of the aortic arch, thrombus (*), and IMH (arrow). (b) Contrast-enhanced CT scan shows outflow of contrast material from the aortic lumen.

View larger version (119K): [in a new window]   Figure 15b.  Saccular aneurysm in the aortic arch caused by a penetrating atherosclerotic ulcer. (a) Unenhanced CT scan shows saccular dilatation of the aortic arch, thrombus (*), and IMH (arrow). (b) Contrast-enhanced CT scan shows outflow of contrast material from the aortic lumen.

View larger version (127K): [in a new window]   Figure 16a.  Rupture of penetrating atherosclerotic ulcer. (a) Unenhanced CT scan of the aortic arch shows an atherosclerotic aorta with displaced intimal calcifications (black arrow), subintimal hematoma (arrowhead), and hemothorax (white arrow). (b) Contrast-enhanced CT scan shows the ulcerated aortic lesion and outflow of contrast material from the aortic lumen (arrow).

View larger version (125K): [in a new window]   Figure 16b.  Rupture of penetrating atherosclerotic ulcer. (a) Unenhanced CT scan of the aortic arch shows an atherosclerotic aorta with displaced intimal calcifications (black arrow), subintimal hematoma (arrowhead), and hemothorax (white arrow). (b) Contrast-enhanced CT scan shows the ulcerated aortic lesion and outflow of contrast material from the aortic lumen (arrow).

View larger version (98K): [in a new window]   Figure 17a.  Suspected pulmonary thromboembolism in a patient without pain. (a) Unenhanced CT scan shows atheromatous changes in the descending aorta but no evidence of IMH. (b) Contrast-enhanced CT scan shows multiple ulcerlike lesions.

View larger version (93K): [in a new window]   Figure 17b.  Suspected pulmonary thromboembolism in a patient without pain. (a) Unenhanced CT scan shows atheromatous changes in the descending aorta but no evidence of IMH. (b) Contrast-enhanced CT scan shows multiple ulcerlike lesions.

View larger version (87K): [in a new window]   Figure 18.  Rupture of Stanford type A typical aortic dissection in a patient with aortic coarctation (same patient as in Fig 3). Unenhanced CT scan shows high-attenuating pericardial effusion (arrows). Note the decreased diameter of the descending aorta.

View larger version (127K): [in a new window]   Figure 19.  Rupture of penetrating atherosclerotic ulcer. Unenhanced CT scan shows mediastinal hematoma with heterogeneous attenuation, indicating recent bleeding (*). Note the high attenuation of a pleural effusion (arrow), a finding indicative of hemothorax.

View larger version (87K): [in a new window]   Figure 20a.  Rupture of Stanford type A typical aortic dissection. (a) Contrast-enhanced CT scan shows stenosis of the pulmonary arteries, which are enveloped in a hemorrhagic sheath. (b) Magnified view shows the detail of the stenosis around the left lower lobe pulmonary artery (arrows). (c) Scan at lung window setting shows areas of alveolar opacity in the right upper lobe caused by diffusion of blood through the peribronchovascular hilar sheath. (d) Posterior view of the autopsy specimen shows hemorrhage in the ascending aorta (arrows) and surrounding the pulmonary arteries (arrowheads). (e) Drawing provides a posterior view of the anatomic pathway from the ascending aorta to the pulmonary interstitium.

View larger version (86K): [in a new window]   Figure 20b.  Rupture of Stanford type A typical aortic dissection. (a) Contrast-enhanced CT scan shows stenosis of the pulmonary arteries, which are enveloped in a hemorrhagic sheath. (b) Magnified view shows the detail of the stenosis around the left lower lobe pulmonary artery (arrows). (c) Scan at lung window setting shows areas of alveolar opacity in the right upper lobe caused by diffusion of blood through the peribronchovascular hilar sheath. (d) Posterior view of the autopsy specimen shows hemorrhage in the ascending aorta (arrows) and surrounding the pulmonary arteries (arrowheads). (e) Drawing provides a posterior view of the anatomic pathway from the ascending aorta to the pulmonary interstitium.

View larger version (109K): [in a new window]   Figure 20c.  Rupture of Stanford type A typical aortic dissection. (a) Contrast-enhanced CT scan shows stenosis of the pulmonary arteries, which are enveloped in a hemorrhagic sheath. (b) Magnified view shows the detail of the stenosis around the left lower lobe pulmonary artery (arrows). (c) Scan at lung window setting shows areas of alveolar opacity in the right upper lobe caused by diffusion of blood through the peribronchovascular hilar sheath. (d) Posterior view of the autopsy specimen shows hemorrhage in the ascending aorta (arrows) and surrounding the pulmonary arteries (arrowheads). (e) Drawing provides a posterior view of the anatomic pathway from the ascending aorta to the pulmonary interstitium.

View larger version (94K): [in a new window]   Figure 20d.  Rupture of Stanford type A typical aortic dissection. (a) Contrast-enhanced CT scan shows stenosis of the pulmonary arteries, which are enveloped in a hemorrhagic sheath. (b) Magnified view shows the detail of the stenosis around the left lower lobe pulmonary artery (arrows). (c) Scan at lung window setting shows areas of alveolar opacity in the right upper lobe caused by diffusion of blood through the peribronchovascular hilar sheath. (d) Posterior view of the autopsy specimen shows hemorrhage in the ascending aorta (arrows) and surrounding the pulmonary arteries (arrowheads). (e) Drawing provides a posterior view of the anatomic pathway from the ascending aorta to the pulmonary interstitium.

View larger version (52K): [in a new window]   Figure 20e.  Rupture of Stanford type A typical aortic dissection. (a) Contrast-enhanced CT scan shows stenosis of the pulmonary arteries, which are enveloped in a hemorrhagic sheath. (b) Magnified view shows the detail of the stenosis around the left lower lobe pulmonary artery (arrows). (c) Scan at lung window setting shows areas of alveolar opacity in the right upper lobe caused by diffusion of blood through the peribronchovascular hilar sheath. (d) Posterior view of the autopsy specimen shows hemorrhage in the ascending aorta (arrows) and surrounding the pulmonary arteries (arrowheads). (e) Drawing provides a posterior view of the anatomic pathway from the ascending aorta to the pulmonary interstitium.

View larger version (72K): [in a new window]   Figure 21a.  Rupture of Stanford type A typical aortic dissection along the sheath of the pulmonary arteries. (a) Unenhanced CT scan shows lines of high attenuation along the common trunk and main right pulmonary artery (arrows). (b) Contrast-enhanced CT scan shows pulmonary lumen stenosis (arrows). Note the intimal flaps in the ascending and descending aorta.

View larger version (86K): [in a new window]   Figure 21b.  Rupture of Stanford type A typical aortic dissection along the sheath of the pulmonary arteries. (a) Unenhanced CT scan shows lines of high attenuation along the common trunk and main right pulmonary artery (arrows). (b) Contrast-enhanced CT scan shows pulmonary lumen stenosis (arrows). Note the intimal flaps in the ascending and descending aorta.

View larger version (78K): [in a new window]   Figure 22.  Typical aortic dissection with supraaortic trunk involvement. Contrast-enhanced CT scan shows intimal flaps (arrows) in the innominate trunk and left carotid artery.

View larger version (131K): [in a new window]   Figure 23a.  Static obstruction of the celiac trunk and right renal artery. (a) Contrast-enhanced CT scan shows the intimal flap entering the celiac trunk. The true lumen (*) is narrowed by a thrombotic false lumen (arrow). The liver blood supply is not visible on this arterial-phase image. (b) Contrast-enhanced CT scan obtained at a lower level shows the intimal flap (white arrow) entering the left renal artery and producing a left renal infarct (black arrow).

View larger version (165K): [in a new window]   Figure 23b.  Static obstruction of the celiac trunk and right renal artery. (a) Contrast-enhanced CT scan shows the intimal flap entering the celiac trunk. The true lumen (*) is narrowed by a thrombotic false lumen (arrow). The liver blood supply is not visible on this arterial-phase image. (b) Contrast-enhanced CT scan obtained at a lower level shows the intimal flap (white arrow) entering the left renal artery and producing a left renal infarct (black arrow).

View larger version (133K): [in a new window]   Figure 24.  Iliac artery extension from aortic dissection. Contrast-enhanced CT scan shows intimal flaps (arrows) in both common iliac arteries.