Rupture signs on computed tomography, treatment, and outcome of abdominal aortic aneurysms

Abstract

Objectives: Abdominal aortic aneurysm (AAA) rupture has a high mortality rate. Although the diagnosis of a ruptured AAA is usually straightforward, detection of impending rupture signs can be more challenging. Early diagnosis of impending AAA rupture can be lifesaving. Furthermore, differentiating between impending and complete rupture has important repercussions on patient management and prognosis. The purpose of this article is to classify and illustrate the entire spectrum of AAA rupture signs and to review current treatment options for ruptured AAAs.

Methods: Using medical illustrations supplemented with computed tomography (CT), this essay showcases the various signs of impending rupture and ruptured AAAs. Endovascular aneurysm repair (EVAR) and open surgical repair are also discussed as treatment options for ruptured AAAs.

Results: CT imaging findings of ruptured AAAs can be categorised according to location: intramural, luminal, and extraluminal. Intramural signs generally indicate impending AAA rupture, whereas luminal and extraluminal signs imply complete rupture. EVAR has emerged as an alternative and possibly less morbid method to treat ruptured AAAs.

Conclusions: AAA rupture occurs at the end of a continuum of growth and wall weakening. This review describes the CT imaging findings that may help identify impending rupture prior to complete rupture.

Teaching points: • AAA rupture occurs at the end of a continuum of growth and wall weakening. • Intramural imaging findings indicate impending AAA rupture. • Luminal and extraluminal imaging findings imply complete AAA rupture. • Some imaging findings are not specific to AAA ruptures and can be seen in other pathologies. • EVAR has emerged as an alternative and possibly less morbid method of treating ruptured AAAs.

Figures

Fig. 1

Rapid enlargement rate. a Axial enhanced CT and b 3D rendering image with a colour parametric map of a 71-year-old man shows a 5.4-cm AAA. c Axial enhanced CT and d 3D rendering image with a colour parametric map of the same patient performed a year later shows a 1 cm increase in diameter

Fig. 2

Focal wall discontinuity. a Illustration depicts a focal discontinuity (white arrow) of the calcified intima walls (C), indicating the AAA rupture site. b Axial unenhanced CT image of an asymptomatic 56-year-old man shows a 4.2 cm AAA with intact circumferential calcified walls. c Axial unenhanced CT image of the same patient who presented with severe lumbar pain 4 years later. The AAA now measures 5.7 cm, and a new 1 cm focal gap (white arrow) of the circumferential calcifications can be seen with periaortic fat infiltration near the rupture site (white arrowhead)

Fig. 3

Hyperattenuating crescent sign. a Illustration demonstrates blood (black arrow) dissecting into a mural thrombus (T) from the aortic lumen (L). The resulting intramural haematoma (H) is crescent shaped. b Axial unenhanced CT of a 63-year-old man presenting with abdominal pain and a pulsating mass. A crescent (H) of higher attenuation than the aortic lumen (L) can be seen

Fig. 4

Thrombus fissuration. a Illustration demonstrates blood (black arrow) dissecting from the aortic lumen (L) into a mural thrombus (T). The infiltrating blood is seen as linear fissurations (white arrows). b Axial and c coronal enhanced CT of a 64-year-old man shows linear infiltrations of contrast material (white arrows) within the hypodense mural thrombus. The patient underwent successful emergent AAA repair before complete rupture occurred

Fig. 5

Draped aorta sign. a Illustration depicts loss of normal aneurysm wall convexity. The posterior wall of the aorta moulds to the anterior surface of the vertebral body. b Axial enhanced CT of an 85-year-old man with abdominal pain. The posterior aortic wall follows the contour of the anterior portion of the vertebra, with loss of fat planes between the aneurysm and vertebra (white arrowheads). Discrete thrombus fissuration (white arrow) is also seen. These are both signs of impending AAA rupture

Fig. 6

Aortoenteric fistula. a Illustration depicts a fistulous tract connecting a bowel loop to an aortic aneurysm. The white double-headed arrow shows communication between the structures allowing bowel gas to infiltrate into the aortic wall and blood to leak into the bowel lumen. b Sagittal enhanced CT image of a 73-year-old man demonstrates an aortoenteric fistula. Intraluminal gas (white arrow) is observed within the AAA, and normal fat planes between the aneurysm and the third portion of the duodenum are lost (white arrowhead). c Axial enhanced CT of an 82-year-old man who presented with massive lower gastrointestinal bleeding and a history of previously repaired AAA. Active contrast extravasation (white arrow) into the third portion of the duodenum (D) and the stomach (S) can be seen in this patient with an aortoenteric fistula

Fig. 7

Aortocaval fistula. a Axial arterial phase enhanced CT shows simultaneous enhancement of the AAA and IVC in an 83-year-old man with AAA rupture and retroperitoneal haematoma (R). b Axial enhanced CT of the same patient at a lower level demonstrates active contrast extravasation (white arrows) from the aortic aneurysm to the IVC with loss of normal fat planes between the structures. Retroperitoneal haematoma (R) can also be seen

Fig. 8

Periaortic stranding. a Axial and b coronal enhanced CT of a 51-year-old man with abdominal pain shows stranding of periaortic fat (white arrows) before any retroperitoneal haematoma can be seen

Fig. 9

Contrast extravasation. a-b Axial enhanced CT of a 75-year-old woman demonstrates active contrast extravasation (white arrows) from the aneurysm lumen (L) into the retroperitoneal space with massive retroperitoneal haematoma (R)

Fig. 10

Retroperitoneal haematoma. a Axial unenhanced CT image of a 72-year-old man demonstrates haemorrhage involving bilateral anterior (AP) and posterior (PP) pararenal spaces as well as the area along the psoas muscles. The left kidney is displaced laterally. Attenuation of 45 HU (more than 30 HU) indicates acute haematoma. b Coronal unenhanced CT image of the same patient shows bilateral retroperitoneal haematomas (white arrows)

Fig. 11

Intraperitoneal haematoma. a Illustration depicts AAA rupture of the left anterolateral wall (white arrow). Massive haemorrhage extends into both the retroperitoneal (R, shown as translucent red blood) and intraperitoneal (I, shown as more opaque blood) spaces. b Coronal unenhanced CT of a 51-year-old man demonstrates intraperitoneal haematoma involving the perihepatic space (PH), right (RG), and left (LG) paracolic gutters. Retroperitoneal haematoma (white arrows) is also seen. Attenuation of 60 HU indicates acute haemorrhage. c Axial unenhanced CT of the same patient shows right (RG) and left (LG) paracolic gutters, as well as retroperitoneal haematoma (white arrows)

Fig. 12

Open surgical repair. a Axial and b coronal unenhanced CT image of a 73-year-old man demonstrates ruptured AAA with a retroperitoneal haematoma (R). c Sagittal enhanced CT image of the same patient after successful open surgical repair shows the junction between the native aorta and aortic graft (white arrow) and a surgical clip (black arrow)

Fig. 13

Endovascular aneurysm repair. a Coronal enhanced CT image of an 85-year-old man presenting with an impending AAA rupture (same as Fig. 5) demonstrates a large AAA (white arrow) with a long proximal neck (white arrowheads). b Fluoroscopy image, c axial, and d 3D rendering of the same patient show a deployed aorto-biiliac stent-graft (white arrows)