Is aortic angiography necessary for accurate planning of endovascular aortic aneurysm stents?

Endovascular management of abdominal aortic aneurysms (AAA) relies upon accurate stent design. We hypothesized the length of the stent could be measured from computed tomogram (CT) generated 3D surface rendered images of the abdominal vessels, eliminating the need for digital subtraction angiography (DSA).

The CT scans from a consecutive series of 54 patients considered for endovascular AAA repair were reviewed. A TRIFAB Zenith (Cook) endovascular aortic stent was designed, using the manufacturer's sizing computer program. These hypothetical stents were compared to those that had been implanted, using measurements from both angiogram and CT (Spearman's test of correlation (p<0.05)).

The stent body size and short limb extension (SLE) of stents in each group was similar (correlation coefficient 0.70(p<0.01) and 0.50 (p=0.014)), however, CT alone significantly underestimated the length of the long limb extension (LLE) (correlation coefficient 0.095).

These data suggest that CT underestimates the tortuosity of iliac vessels. Aortic angiography is necessary for accurate AAA endovascular stent design.