Figure 6.

Two types of coronary atherosclerotic plaques and corresponding geometric models. In both models, R, r, and h are the external radius, internal radius, and height on the centerline. In model 1, L₁ describes the longest segment along the longitudinal direction on the surface. L₂ describes the segment from one end of L₁ to the opposite side. L₁ and L₂ form a plane across the centerline of the cylinder. θ₁ and θ₂ describe the dihedral angles between slanted surface planes and the perpendicular cross-section plane at both ends. In model 2, θ describes the circumferential range of the partial ring.