Table 2.

Definition of shape indices.

Shape indices	Index	Definition
Indices 0D	α	Bifurcation angle (the angle between the right and left iliac arteries)
Indices 2D	χ	Deformation rate D/Dpn (characterizes the actual deformation of the aorta, thus constituting a relationship between the maximum diameter of the aneurysm, D, and the proximal neck diameter, Dpn).
	γ	Saccular index D/L (assesses the length of the AAA region, which is the region affected by the formation and further development of the aneurysm, determined by the relationship between D and L).
	T	Tortuosity (the arc-chord ratio; the ratio of the length of the curve to the distance between its ends).
	e	Asymmetry (the result of the non-symmetry expansion of the aneurysm sac as a result of the expansion constraints introduced by the proximity to the spinal column). e = (D-La)/La, where D is the maximum diameter of the aneurysm and La is anterior length measured in the plane of maximum diameter.