Risk assessment with coronary artery calcium screening

Abstract

Direct relationships between coronary artery calcification (CAC) and the presence, and to a modest degree, the extent and severity of coronary atherosclerotic disease (CAD) have been demonstrated in comparisons based on histology (Rumberger 1995), ultrasound (Baumgart 1997), and angiography (Kajinami 1997). This correlation of CAC with the amount of coronary artery plaque has raised significant interest in the noninvasive detection and quantification of coronary calcium for diagnosing coronary atherosclerosis and estimating the prognosis of patients with coronary heart disease. Electron-beam CT (EBCT) was the first accurate and sensitive noninvasive technique with which to quantify coronary calcium and it has been used in most clinical studies. Therefore, the relevant clinical data to date come from studies that were carried out using this specific CT technology and based on a standardized method for imaging, identifying, and quantifying calcified coronary artery plaque. Despite the different scanner technologies, major disagreements between cal cium quantification results obtained in the same patients by EBCT vs. multi-slice CT have not been reported (Becker 2001, Stanford 2004). Recent studies indicate that CAC quantification plays an important role in the assessment of cardiovascular disease risk in asymptomatic individuals with subclinical atherosclerosis. In this context, the primary goal in calcium scanning is to detect and quantify calcified coronary artery plaque and not to identify significant coronary artery obstruction, as is done in coronary CTA. The introduction of multislice CT has brought a rapidly increasing variety of multi-purpose CT systems that allow cardiac scanning using prospective ECG triggering or retrospective ECG gating. While this has allowed CAC quantification to become available to larger populations, it has made standardization of image acquisition protocols and quantification methods an increasingly important clinical issue. © 2007 Springer-Verlag Berlin Heidelberg.