As a plaque progresses in size (left to right), compensatory changes occur in the vessel wall that result in dilatation of vessel cross section and preservation of the original luminal diameter. The media underlying a plaque undergoes atrophy and the smooth muscle of the plaque-free wall hypertrophies. (Reprinted with permission from Miller D. Pathology of coronary artery atherosclerosis: aspects relevant to cardiac imaging. In: Gerber T, Kantor B, Williamson E, editors. Computed Tomography for the Cardiovascular System. London, UK: Informa Healthcare, 2008.)