DOI: 10.1148/rg.272065026
RadioGraphics 2007;27:497-507
© RSNA, 2007
Spectrum of CT Findings in Rupture and Impending Rupture of Abdominal Aortic Aneurysms1
Dmitry Rakita, MD,
Amit Newatia, MD,
John J. Hines, MD,
David N. Siegel, MD and
Barak Friedman, MD
1 From the Department of Radiology, Division of Body Imaging and Division of Interventional Radiology, Long Island Jewish Medical Center, 270-05 76th Ave, New Hyde Park, NY 11040. Presented as an education exhibit at the 2005 RSNA Annual Meeting. Received March 16, 2006; revision requested June 14 and received August 4; accepted August 10. All authors have no financial relationships to disclose.
Address correspondence to D.R. (e-mail: rakitamd{at}gmail.com).
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Abstract
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Prompt diagnosis of rupture and impending rupture of abdominal aortic aneurysms is imperative. The computed tomographic (CT) findings of ruptured abdominal aortic aneurysms are often straightforward. Most ruptures are manifested as a retroperitoneal hematoma accompanied by an abdominal aortic aneurysm. Periaortic blood may extend into the perirenal space, the pararenal space, or both. Intraperitoneal extravasation may be an immediate or a delayed finding. Discontinuity of the aortic wall or a focal gap in otherwise continuous circumferential wall calcifications may point to the location of a rupture. There usually is a delay of several hours between the initial intramural hemorrhage and frank extravasation into the periaortic soft tissues. Contained or impending ruptures are more difficult to identify. A small amount of periaortic blood may be confused with the duodenum, perianeurysmal fibrosis, or adenopathy. Imaging features suggestive of instability or impending rupture include increased aneurysm size, a low thrombus-to-lumen ratio, and hemorrhage into a mural thrombus. A peripheral crescent-shaped area of hyperattenuation within an abdominal aortic aneurysm represents an acute intramural hemorrhage and is another CT sign of impending rupture. Draping of the posterior aspect of an aneurysmal aorta over the vertebrae is associated with a contained rupture.
© RSNA, 2007
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LEARNING OBJECTIVES
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After reading this article and taking the test, the reader will be able to:- Recognize the imaging features of instability, impending rupture, and rupture of abdominal aortic aneurysms.
- Describe the utility of gadolinium as a contrast agent for CT angiography.
- Identify the etiology and imaging features of infected abdominal aortic aneurysms and aortoenteric fistula.
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Introduction
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Most abdominal aortic aneurysms are true aneurysms. A true aortic aneurysm is a localized dilatation of the aorta caused by weakening of its wall; it involves all three layers (intima, media, and adventitia) of the arterial wall. A pseudoaneurysm (false aneurysm) is a collection of flowing blood that communicates with the arterial lumen but is not enclosed by the normal vessel wall; it is contained only by the adventitia or surrounding soft tissue (Fig 1). Aneurysms may develop in any segment of the aorta, but most involve the aortic segment below the renal arteries. An aortic diameter of 3 cm or more is used to define an abdominal aortic aneurysm (1). Aneurysmal dilatation of the abdominal aorta is a disease of aging and is rare before age 50 but is found in 2%–4% of the population older than 50 years (2). The average age at the time of diagnosis is 65–70 years, and more men than women are affected. Concurrent coronary artery disease and peripheral vascular disease, as well as a family history of abdominal aortic aneurysm, are strong risk factors for the development of this condition.
A retroperitoneal hematoma adjacent to an abdominal aortic aneurysm is the most common imaging finding of rupture (3). Extension of hemorrhage into the retroperitoneum, including the perirenal and pararenal spaces, psoas muscles, and peritoneum, is a common occurrence. Intra-peritoneal extravasation may be an immediate or a delayed finding.
Patients who present with abdominal pain, a large abdominal aortic aneurysm, and no frank rupture pose a diagnostic dilemma. The symptoms may be attributable to aneurysmal instability, impending rupture, or a contained leak.
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Imaging Techniques
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Computed tomography (CT) is the modality of choice for evaluation of acute aortic syndrome, because of the speed of the examination and the widespread availability of CT. With a multidetector CT scanner in the emergency department, an examination can be performed and the images interpreted within minutes. Magnetic resonance (MR) imaging requires a much longer acquisition time, and MR imaging may be less available and less convenient. Ultrasonography (US) plays a limited role in the assessment of acute aortic abnormalities. Frequently, the entire aorta cannot be evaluated because of overlying bowel gas and body habitus. In addition, US is operator dependent, and the necessary expertise may not be readily available. A bedside examination with US may be helpful for patients whose condition is too unstable to allow their transfer to the CT scanner. US may help determine the size of the aneurysm and help identify hemoperitoneum. However, the utility of US for identifying an impending rupture or a contained rupture of an aneurysm is limited.
The use of CT angiography has become routine for imaging of a suspected abdominal aortic aneurysm rupture. Because the clinical signs and symptoms frequently are confused with those of appendicitis, pancreatitis, or bowel obstruction, abdominal aortic aneurysm rupture sometimes is detected at a nonemergent CT evaluation for nonspecific abdominal pain or renal colic.
Unenhanced CT may help detect an aneurysm rupture by depicting an abdominal aortic aneurysm with surrounding retroperitoneal hemorrhage. Contrast-enhanced CT provides additional information about the size of the aneurysmal lumen, presence of active extravasation, and relationship of the aneurysm to the celiac, superior mesenteric, renal, and inferior mesenteric arteries. Our abdominal aortic aneurysm CT protocol, performed on a four– or 16–detector row scanner, consists of unenhanced scanning through the abdomen and pelvis at 5-mm collimation, followed by bolus-tracked CT angiography of the abdomen and pelvis at 1-mm collimation and then by delayed imaging of the abdomen and pelvis in the portal venous phase (80 seconds) at 5-mm collimation. The acquisition of thin sections is essential for multiplanar reformatting, evaluating the relationship of the aneurysm to other abdominal vascular structures, and planning endovascular stent-graft placement. Contrast injection rates of 3–4 mL/sec are optimal; however, slower rates of 1.5–2 mL/sec yield images with diagnostic quality. A total of 90 mL of nonionic intravenous contrast material is sufficient to reliably produce diagnostic-quality images. Oral contrast material is not administered.
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Findings of Aneurysm Rupture
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A retroperitoneal hematoma adjacent to an abdominal aortic aneurysm is the most common imaging finding of abdominal aortic aneurysm rupture (3).
Periaortic blood may extend into the perirenal space, pararenal space, or the psoas muscles. Intraperitoneal extension may be an immediate or a delayed finding. These findings are readily visible on unenhanced CT images, which may have been obtained for another indication or as part of an aneurysm evaluation protocol. On contrast-enhanced CT images, active extravasation of contrast material is frequently demonstrated (Figs 2, 3). Although open surgical techniques have traditionally been used to repair ruptured aneurysms, endovascular repair (Fig 4) has gained increasing acceptance for elective use in patients who are at high risk for complications from open surgery and for relatively stable patients (4,5).
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Figure 2a. Aortic aneurysm rupture in an 80-year-old woman with abdominal pain and hypotension. Axial (a) and sagittal (b) CT angiographic images demonstrate active extravasation of contrast material (arrow) into the thrombosed portion of an abdominal aortic aneurysm, as well as extensive retroperitoneal hemorrhage (arrowhead).
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Figure 2b. Aortic aneurysm rupture in an 80-year-old woman with abdominal pain and hypotension. Axial (a) and sagittal (b) CT angiographic images demonstrate active extravasation of contrast material (arrow) into the thrombosed portion of an abdominal aortic aneurysm, as well as extensive retroperitoneal hemorrhage (arrowhead).
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Figure 3a. Aortic aneurysm rupture in a 67-year-old man with abdominal pain and hypotension. Axial CT angiographic images depict a large ruptured abdominal aortic aneurysm with active retroperitoneal extravasation (arrow in a) and intraperitoneal hemorrhage (arrow in b).
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Figure 3b. Aortic aneurysm rupture in a 67-year-old man with abdominal pain and hypotension. Axial CT angiographic images depict a large ruptured abdominal aortic aneurysm with active retroperitoneal extravasation (arrow in a) and intraperitoneal hemorrhage (arrow in b).
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Figure 4a. Aortic aneurysm rupture in a 68-year-old man with abdominal and right hip pain. (a, b) Axial contrast-enhanced CT images (a at a level higher than b) show a retroperitoneal hemorrhage (arrowhead) and a right psoas hematoma (arrow). (c) Post-treatment angiogram shows successful repair of the ruptured aneurysm with endovascular stent placement.
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Figure 4b. Aortic aneurysm rupture in a 68-year-old man with abdominal and right hip pain. (a, b) Axial contrast-enhanced CT images (a at a level higher than b) show a retroperitoneal hemorrhage (arrowhead) and a right psoas hematoma (arrow). (c) Post-treatment angiogram shows successful repair of the ruptured aneurysm with endovascular stent placement.
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Figure 4c. Aortic aneurysm rupture in a 68-year-old man with abdominal and right hip pain. (a, b) Axial contrast-enhanced CT images (a at a level higher than b) show a retroperitoneal hemorrhage (arrowhead) and a right psoas hematoma (arrow). (c) Post-treatment angiogram shows successful repair of the ruptured aneurysm with endovascular stent placement.
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Some patients who are believed to have a ruptured abdominal aortic aneurysm may have a contraindication (eg, allergy) to the use of iodinated intravenous contrast media. CT angiography with the use of gadolinium as a contrast agent may be an effective alternative option (Fig 5). Gadolinium-enhanced CT angiography requires a high dose of the contrast agent (0.3–0.5 mmol/kg), and imaging is best performed with a multidetector CT scanner with 16 channels or more to allow rapid acquisition, as the volume of gadolinium is smaller than that of an iodinated contrast agent and because there is a smaller temporal window of adequate opacification (6,7). However, the use of high-dose gadolinium as a substitute for iodinated contrast material is controversial in patients at risk for nephrotoxic effects or with preexisting renal insufficiency (8).
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Figure 5a. Aortic aneurysm rupture superior to an aortobiiliac stent-graft in a 75-year-old man with chronic renal insufficiency and abdominal pain after endovascular repair. Axial (a at a level higher than b) and sagittal (c) gadolinium-enhanced CT angiographic images demonstrate active extravasation of contrast material superior to the graft (arrowhead in b and c) and retroperitoneal hemorrhage around the aorta (arrow).
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Figure 5b. Aortic aneurysm rupture superior to an aortobiiliac stent-graft in a 75-year-old man with chronic renal insufficiency and abdominal pain after endovascular repair. Axial (a at a level higher than b) and sagittal (c) gadolinium-enhanced CT angiographic images demonstrate active extravasation of contrast material superior to the graft (arrowhead in b and c) and retroperitoneal hemorrhage around the aorta (arrow).
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Figure 5c. Aortic aneurysm rupture superior to an aortobiiliac stent-graft in a 75-year-old man with chronic renal insufficiency and abdominal pain after endovascular repair. Axial (a at a level higher than b) and sagittal (c) gadolinium-enhanced CT angiographic images demonstrate active extravasation of contrast material superior to the graft (arrowhead in b and c) and retroperitoneal hemorrhage around the aorta (arrow).
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An important imaging feature that may be seen in a contained rupture of an abdominal aortic aneurysm is the draped aorta sign (9). This sign is considered present when the posterior wall of the aorta either is not identifiable as distinct from adjacent structures or when it closely follows the contour of adjacent vertebral bodies (Fig 6).
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Figure 6a. Draped aorta sign in a 55-year-old man with a known abdominal aortic aneurysm and recent vague back pain. Axial CT angiographic images (a at a level higher than b) depict an 8-cm abdominal aortic aneurysm with a posterior aortic wall that follows the contour of the vertebral bodies with a draping effect (arrow in b). The latter finding is indicative of a contained rupture.
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Figure 6b. Draped aorta sign in a 55-year-old man with a known abdominal aortic aneurysm and recent vague back pain. Axial CT angiographic images (a at a level higher than b) depict an 8-cm abdominal aortic aneurysm with a posterior aortic wall that follows the contour of the vertebral bodies with a draping effect (arrow in b). The latter finding is indicative of a contained rupture.
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Findings Predictive of Impending Rupture
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Increased Aneurysm Size
The most common finding predictive of rupture and, thus, the most common indicator for elective surgical management, is the maximum diameter of the aneurysm (10). Wall tension in aortic aneurysms is proportional to the mean vessel radius, according to the Laplace law T = PR, in which T is the circumferential wall tension, P is the trans-mural pressure, and R is the vessel radius. A patient with a very large abdominal aortic aneurysm (diameter of > 7 cm) who presents with symptoms of acute aortic syndrome has a high likelihood of aneurysm rupture (Fig 7). Furthermore, an enlargement rate of 10 mm or more per year is also used as an indication for surgical repair (10).
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Figure 7a. Large ruptured aneurysm in a 68-year-old man with an acute onset of right flank pain radiating to the back. Axial unenhanced CT images (a at a level higher than b) depict a ruptured 10.7-cm abdominal aortic aneurysm and a retroperitoneal hemorrhage (arrow).
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Figure 7b. Large ruptured aneurysm in a 68-year-old man with an acute onset of right flank pain radiating to the back. Axial unenhanced CT images (a at a level higher than b) depict a ruptured 10.7-cm abdominal aortic aneurysm and a retroperitoneal hemorrhage (arrow).
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Thrombus and Calcifications
Nonruptured aneurysms generally contain more thrombus than do ruptured aneurysms, and the thrombus-to-lumen ratio decreases with increasing aneurysm size (11). These observations suggest that a thick circumferential thrombus is protective against rupture. In addition, enlargement of the patent lumen is indicative of partial lysis of the thrombus, which predisposes an aneurysm to rupture (11,12).
A focal discontinuity in circumferential wall calcifications is more commonly observed in unstable or ruptured aneurysms (3). This finding is most helpful when a previous CT study is available and its comparison with the current CT study shows that an area of discontinuity in mural calcifications is new (Fig 8).
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Figure 8a. Discontinuity of aortic wall calcifications in an abdominal aortic aneurysm in a 60-year-old woman. Axial unenhanced CT images from two examinations of the same patient in 2003 (a) and 2005 (b) demonstrate the development of discontinuity in calcifications and of draping of the posterior aortic wall (arrow in b).
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Figure 8b. Discontinuity of aortic wall calcifications in an abdominal aortic aneurysm in a 60-year-old woman. Axial unenhanced CT images from two examinations of the same patient in 2003 (a) and 2005 (b) demonstrate the development of discontinuity in calcifications and of draping of the posterior aortic wall (arrow in b).
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Hyperattenuating Crescent Sign
A well-defined peripheral crescent of increased attenuation within the thrombus of a large abdominal aortic aneurysm is a CT sign of acute or impending rupture (13,14). This finding is best appreciated on unenhanced CT images (Figs 9, 10). It represents an internal dissection of blood into either the peripheral thrombus or the aneurysm wall, a process that either causes or results from a loss in the ability of the thrombus to protect the aneurysm from rupture (15). It is one of the earliest and most specific imaging manifestations of the rupture process (3,13–15).
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Figure 9a. Impending aneurysm rupture in a 66-year-old man with back pain, who underwent imaging for suspicion of renal colic. Axial unenhanced CT images (a and b are the same section with different window settings) demonstrate an abdominal aortic aneurysm with a hyperattenuating crescent sign (arrow) that represents an acute hematoma within the aneurysm wall.
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Figure 9b. Impending aneurysm rupture in a 66-year-old man with back pain, who underwent imaging for suspicion of renal colic. Axial unenhanced CT images (a and b are the same section with different window settings) demonstrate an abdominal aortic aneurysm with a hyperattenuating crescent sign (arrow) that represents an acute hematoma within the aneurysm wall.
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Figure 10a. Impending aneurysm rupture in a 57-year-old man with a known abdominal aortic aneurysm and increasing abdominal pain. Axial unenhanced (a) and axial contrast-enhanced (b) CT images depict an abdominal aortic aneurysm with a hyperattenuating crescent sign (arrow in a), which represents an acute hematoma within the aneurysm wall.
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Figure 10b. Impending aneurysm rupture in a 57-year-old man with a known abdominal aortic aneurysm and increasing abdominal pain. Axial unenhanced (a) and axial contrast-enhanced (b) CT images depict an abdominal aortic aneurysm with a hyperattenuating crescent sign (arrow in a), which represents an acute hematoma within the aneurysm wall.
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Infected Aneurysms
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Infected (mycotic) aneurysms are uncommon and account for only 0.7%–2.6% of aortic aneurysms; they are most often pseudoaneurysms. Infected aneurysms are prone to rupture, with a rupture rate of 53%–75% at surgical repair. Hematogenous seeding of the aorta usually occurs in the setting of septicemia, which is most commonly caused by endocarditis (16). The direct spread of infection from adjacent vertebral osteomyelitis and from renal and psoas abscesses also has been documented (16). Whereas most atherosclerotic aortic aneurysms occur in the infrarenal abdominal aorta, the majority of infected aneurysms occur in the thoracic or suprarenal abdominal aorta (16).
CT findings of infected aneurysms include a saccular shape; lobular contours; and periaortic inflammation, abscess, and mass. Other findings include periaortic gas and adjacent vertebral body abnormalities due to the spread of infection (Figs 11, 12). Rapid change in the size or shape of a saccular aneurysm on serial CT studies over a short time period should arouse suspicion about the possible presence of infection, since the expansion rate of mycotic aneurysms is faster than that of atherosclerotic aneurysms (16).
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Figure 11a. Mycotic pseudoaneurysm with associated vertebral osteomyelitis in a 45-year-old man with back and abdominal pain, fever, and an elevated white blood cell count. Sagittal (a) and axial (b, c) contrast-enhanced CT images (b at a level higher than c) show a large pseudoaneurysm (arrowhead) with communication to the aorta (white arrow). Note the destructive changes in adjacent vertebral bodies (black arrow.)
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Figure 11b. Mycotic pseudoaneurysm with associated vertebral osteomyelitis in a 45-year-old man with back and abdominal pain, fever, and an elevated white blood cell count. Sagittal (a) and axial (b, c) contrast-enhanced CT images (b at a level higher than c) show a large pseudoaneurysm (arrowhead) with communication to the aorta (white arrow). Note the destructive changes in adjacent vertebral bodies (black arrow.)
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Figure 11c. Mycotic pseudoaneurysm with associated vertebral osteomyelitis in a 45-year-old man with back and abdominal pain, fever, and an elevated white blood cell count. Sagittal (a) and axial (b, c) contrast-enhanced CT images (b at a level higher than c) show a large pseudoaneurysm (arrowhead) with communication to the aorta (white arrow). Note the destructive changes in adjacent vertebral bodies (black arrow.)
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Figure 12a. Mycotic aneurysm rupture in a 74-year-old man with abdominal pain and an elevated white blood cell count. Axial (a), sagittal (b), and coronal (c) contrast-enhanced CT images demonstrate a retroperitoneal hematoma (arrowhead) and small bubbles of gas (curved arrow) within the aneurysm lumen and surrounding soft tissue. An adjacent pseudoaneurysm (straight arrow in a and b) also is seen. The differential diagnosis included mycotic aneurysm and aortoduodenal fistula. A mycotic aneurysm was found at surgery.
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Figure 12b. Mycotic aneurysm rupture in a 74-year-old man with abdominal pain and an elevated white blood cell count. Axial (a), sagittal (b), and coronal (c) contrast-enhanced CT images demonstrate a retroperitoneal hematoma (arrowhead) and small bubbles of gas (curved arrow) within the aneurysm lumen and surrounding soft tissue. An adjacent pseudoaneurysm (straight arrow in a and b) also is seen. The differential diagnosis included mycotic aneurysm and aortoduodenal fistula. A mycotic aneurysm was found at surgery.
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Figure 12c. Mycotic aneurysm rupture in a 74-year-old man with abdominal pain and an elevated white blood cell count. Axial (a), sagittal (b), and coronal (c) contrast-enhanced CT images demonstrate a retroperitoneal hematoma (arrowhead) and small bubbles of gas (curved arrow) within the aneurysm lumen and surrounding soft tissue. An adjacent pseudoaneurysm (straight arrow in a and b) also is seen. The differential diagnosis included mycotic aneurysm and aortoduodenal fistula. A mycotic aneurysm was found at surgery.
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Aortoenteric Fistulas
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Primary aortoenteric fistulas are a complication of atherosclerotic aortic aneurysms, whereas secondary aortoenteric fistulas are a complication of aortic reconstructive surgery (17). Most fistulas involve the duodenum, most commonly its third and fourth portions. Symptoms include abdominal pain, hematemesis, and melena.
Primary aortoenteric fistulas may pose a diagnostic dilemma for the clinician, especially in the absence of gastrointestinal tract bleeding. Upper-gastrointestinal-tract endoscopy may help rule out other causes of bleeding but rarely helps diagnose a fistula. CT imaging features include an abdominal aortic aneurysm, often with signs of rupture, and intraluminal and periaortic extraluminal gas (Fig 13). CT with the use of intravenous contrast material may show contrast material extravasation from the aorta into the involved portion of the bowel, if a patent fistula is present (17,18).
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Figure 13a. Aortoduodenal fistula in a 71-year-old woman with a known abdominal aortic aneurysm, abdominal pain, and a guaiac-positive stool test. Axial (a, b), close-up axial (c), and coronal (d) CT angiographic images depict small gas bubbles within a ruptured aneurysm sac (arrows in a, b, and d), as well as disruption of the anterior aortic wall, with a faint fistulous tract between the thrombosed portion of the aortic aneurysm and the third portion of the duodenum (arrowhead in b and c). The differential diagnosis included aortoduodenal fistula and mycotic aneurysm. The patient died of a massive gastrointestinal hemorrhage the next day.
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Figure 13b. Aortoduodenal fistula in a 71-year-old woman with a known abdominal aortic aneurysm, abdominal pain, and a guaiac-positive stool test. Axial (a, b), close-up axial (c), and coronal (d) CT angiographic images depict small gas bubbles within a ruptured aneurysm sac (arrows in a, b, and d), as well as disruption of the anterior aortic wall, with a faint fistulous tract between the thrombosed portion of the aortic aneurysm and the third portion of the duodenum (arrowhead in b and c). The differential diagnosis included aortoduodenal fistula and mycotic aneurysm. The patient died of a massive gastrointestinal hemorrhage the next day.
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Figure 13c. Aortoduodenal fistula in a 71-year-old woman with a known abdominal aortic aneurysm, abdominal pain, and a guaiac-positive stool test. Axial (a, b), close-up axial (c), and coronal (d) CT angiographic images depict small gas bubbles within a ruptured aneurysm sac (arrows in a, b, and d), as well as disruption of the anterior aortic wall, with a faint fistulous tract between the thrombosed portion of the aortic aneurysm and the third portion of the duodenum (arrowhead in b and c). The differential diagnosis included aortoduodenal fistula and mycotic aneurysm. The patient died of a massive gastrointestinal hemorrhage the next day.
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Figure 13d. Aortoduodenal fistula in a 71-year-old woman with a known abdominal aortic aneurysm, abdominal pain, and a guaiac-positive stool test. Axial (a, b), close-up axial (c), and coronal (d) CT angiographic images depict small gas bubbles within a ruptured aneurysm sac (arrows in a, b, and d), as well as disruption of the anterior aortic wall, with a faint fistulous tract between the thrombosed portion of the aortic aneurysm and the third portion of the duodenum (arrowhead in b and c). The differential diagnosis included aortoduodenal fistula and mycotic aneurysm. The patient died of a massive gastrointestinal hemorrhage the next day.
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Surgical exploration is usually necessary to confirm the diagnosis and for treatment.
Secondary aortoenteric fistulas are much more common and must be distinguished from graft infection, since perigraft gas may be seen in both conditions and since both entities may occur as delayed complications of aortic aneurysm repair. Aortoenteric fistulas have been reported to occur between 2 weeks and 8 years after surgery (17,18).
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Inflammatory Aneurysms
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A description of inflammatory aneurysms is included in this article for historical reasons, as slow aneurysmal leakage was initially thought to be its cause (19). The term inflammatory aneurysm was initially used in 1972 (19) to describe aortic aneurysm disease with significant perianeurysmal inflammation and adhesions to surrounding structures. This subtype of aneurysm has been reported to account for 3%–10% of aortic aneurysms and is predominantly found in men (20). In contrast to atherosclerotic aneurysms, most inflammatory aneurysms are symptomatic, and they are associated with an increased risk of rupture irrespective of their size (19–21). In approximately 20%–30% of patients, hydronephrosis or renal failure is present at the time of diagnosis because the inflammatory process involves one or both ureters. In addition, fever, weight loss, and an elevated erythrocyte sedimentation rate may be present (21).
CT imaging features include inflammatory or fibrotic changes in the periaortic regions of the retroperitoneum (Fig 14) (20). The etiology of inflammatory aneurysms is poorly understood but is thought to be related to periaortic retroperitoneal fibrosis and various autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, and giant cell arteritis (22).
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Figure 14a. Inflammatory aneurysm in a 50-year-old man with a known abdominal aortic aneurysm, abdominal pain, and an elevated erythrocyte sedimentation rate. Axial contrast-enhanced CT images (a at a level higher than b) demonstrate a large abdominal aortic aneurysm with circumferential perianeurysmal fibrosis and inflammation (arrow).
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Figure 14b. Inflammatory aneurysm in a 50-year-old man with a known abdominal aortic aneurysm, abdominal pain, and an elevated erythrocyte sedimentation rate. Axial contrast-enhanced CT images (a at a level higher than b) demonstrate a large abdominal aortic aneurysm with circumferential perianeurysmal fibrosis and inflammation (arrow).
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Summary
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Imaging findings of aortic aneurysm rupture vary along a spectrum from impending rupture to contained rupture and from small aortic leaks with subtle infiltration of retroperitoneal fat to frank retroperitoneal or intraperitoneal extravasation. Aortic aneurysms most commonly occur as a consequence of atherosclerotic disease of the aorta. Alternatively, they may be associated with infectious seeding of the native or surgically repaired vessel.
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Abstract
LEARNING OBJECTIVES
