Fig. 1. Measuring the iliac tortuosity index. The iliac tortuosity index was defined by dividing L1 by L2, where L1 (A and B) was the distance along the central lumen line between the common femoral artery and the aortic bifurcation, and L2 (C) was the straight-line distance from the common femoral artery and the aortic bifurcation. In this case, the iliac tortuosity index was 1.65 (233/141).