Angulation can be divided in supra-renal (α) and infra-renal angulation (β), defined as:
- (α): the angle between the proximal AAA neck and the supra-renal aortic axis.
- (β): the angle between the proximal AAA neck and the main axis of the AAA.
To minimize the influence of angulation itself on angle measurements, the angulation should be measured perpendicular to the aortic lumen in the middle of the flexure, the central lumen line (CLL). The sharpest angle of the CLL is considered the true angle of the aortic axis.
