Figure 9b. Curved planar reformation. (a) Three-dimensional volume-rendered image shows the curved course of the right coronary artery. (b) Curved planar image of the right coronary artery shows a cross section of the vessel in its entirety. In this case, several points were selected along the course of the vessel on axial images; semiautomated software then defined an imaging plane that includes the entire length of the vessel. Because the imaging plane is defined by the vessel, other structures in the image are distorted.