Abdominal aortic aneurysm (AAA) is a dilation of the abdominal aorta of more than 3 cm,
and is found in 2%-4% of the population older than 50 years.
This disease carries a considerable risk of rupture,
mainly in those aneurysms with a big diameter,
above all if greater than 7 cm,
and therefore,
a substantial risk of death.
Over 80% of patients with ruptured AAA die before they get to be treated,
percentage that can decrease to less than 10% when surgical or endovascular treatment are performed,
in the early postoperative period.
Thus,
requires the physician´s,
radiologist´s and surgeon´s/interventional radiologist´s prompt intervention.
Imaging technique
Aortic computed tomography (CT) angiography is the modality of choice for evaluating an acute aortic syndrome due to its widespread availability,
its speed and its image quality,
being the examination able to be performed and the images interpreted within minutes,
which is extremely important in this potential life threating disease.
MRI has less availability and requires more time than CT,
and US is not very sensitive for the detection of signs of aortic rupture,
being this imaging technique only recommended in the setting of bedside examinations for patients who are too unstable to allow their transfer to the CT scanner.
CT protocol:
In the setting of a suspicion of an abdominal aortic aneurysm rupture,
the field of view of the CT scan should start from the top of the celiac artery,
include the aneurysm,
and end at the proximal thigh,
where delivery pathways for stent-graft hardware can be evaluated.
The recommended phases to perform in the suspicion of acute aortic syndrome are the following:
-Unenhanced phase: Unenhanced images are used to evaluate arterial wall calcification,
intramural,
peritoneal and retroperitoneal hematomas.
-Arterial phase (45”or » 8” after bolus tracking in abdominal aorta –level D12-L1-): to detect contrast extravasation from the aortic lumen through the aneurysm wall that helps to confirm the rupture.
-Venous delayed phases (70-90”) (optional): on those cases on which there are considerable doubts of the presence of contrast extravasation in the arterial phase.