Figure 3. The Link Between Inflammation, Microcalcification and Macrocalcification.

A large necrotic core, a thin fibrous cap and intense inflammation are key precipitants of acute plaque rupture and myocardial infarction. Intimal calcification is thought to occur as a healing response to this intense necrotic inflammation. However the early stages of microcalcification (detected by 18F-fluoride PET) are conversely associated with an increased risk of rupture. In part this is because of residual plaque inflammation and in part because microcalcification itself increases mechanical stress in the fibrous cap further increasing propensity to rupture. With progressive calcification, plaque inflammation becomes pacified and the necrotic core walled off from the blood pool. The latter stages of macrocalcification (detected by CT) are therefore associated with plaque stability and a lower risk of that plaque rupturing.