[Relationship between Coronary Plaque Stability Evaluated by Intravascular Ultrasound and Laboratory Parameters]

Tissue characteristics of coronary plaque have been reported to be associated with cardiovascular events. The stabilization of vulnerable tissue components such as the lipid pool rather than regression of the plaque volume is considered to be of major benefit in the reduction of cardiovascular events. Conventional echocardiography, especially intravascular ultrasound imaging (IVUS), is widely used to determine calcification and the three layers of the arterial wall. However, differentiation of the lipid pool from fibrous tissue using the echo intensity is difficult. Recently, an integrated backscatter (IB) ultrasound technique was developed. The ultrasound IB power ratio is a function of the difference in acoustic characteristic impedance between the medium and target tissue, and the acoustic characteristic impedance is determined by the density of tissue multiplied by the speed of sound. For more comprehensive plaque analysis using IB-IVUS, three-dimensional IB-IVUS offers the potential for the quantitative volumetric tissue characterization of coronary atherosclerosis. Several large clinical trials demonstrated that lipid-lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) reduces cardiovascular events. The IB techniques provide useful clinical information on the effects of statins and other medications. The presence of lipid-rich plaque is associated with the incidence of atherosclerotic diseases; therefore, ultrasound IB techniques are useful to detect coronary atherosclerotic lesions.