Is there a role for Ultrasound in evaluating abdominal aortic aneurysms?
US is often used as a screening tool for patients at increased risk for an AAA or to monitor patients with a known AAA. Sonographically, the proximal, mid, and distal abdominal aorta are imaged, and their greatest outer diameters are measured in the sagittal and transverse planes. Similar to cross-sectional imaging, an outer abdominal aorta diameter >3.0 cm is considered to indicate an aneurysm. Normally, the abdominal aorta waveform is triphasic, becoming lower resistance with dilation. US can also evaluate the presence and extent of mural thrombus along the abdominal aorta. If intervention is planned for an AAA, computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) is also typically performed to obtain precise measurements regarding the size of the abdominal aorta and iliac arteries, relationship of the AAA to the renal arteries, as well as the patency of abdominal aorta branch vessels.