Electron-Beam Computed Tomography for Coronary Calcium

Abstract

ELECTRON-BEAM COMPUTED TOMOGRAPHY (EBCT) USES x-rays generated by electron-beam irradiation of a tungsten target to identify and quantify coronary artery calcium (CAC). Initial studies focused on the use of EBCT for risk stratification or diagnosis among individuals with clinical symptoms of coronary heart disease (CHD). However, more recent articles, as well as marketing by for-profit companies, have focused on using EBCT for screening; that is, for detection of CHD in asymptomatic individuals. When considering the potential value of EBCT for screening, it is critical to keep in mind generally accepted principles for what constitutes an effective screening test: Disease.—The disease should be common and of public health consequence, have an extended preclinical stage, and result in preventable morbidity or mortality. Diagnosis.—The screening test must accurately classify asymptomatic individuals in the population of interest as likely to have or not have the disease. Therapy.—Detection of subclinical disease must result in treatment that reduces morbidity or mortality in comparison with treatment that would have been received in the absence of the screening result. Practicality.—The test must be acceptable, safe, costeffective, and available for use in the population of interest. Ethics.—The screening program must be ethically justifiable after accounting for intended and unintended consequences of both positive and negative test results.