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In the previous three chapters, we discussed chest imaging for a variety of indications, ignoring one of the most obvious concerns—cardiac ischemia. Among chief complaints to the emergency department, chest pain is the second most common, according to the National Hospital Ambulatory Medical Care Survey,1 and computed tomography (CT) has diagnostic value in ischemic chest pain evaluation and exclusion of pulmonary embolism and aortic dissection (discussed in detail in Chapter 7 ). CT scanners meeting the technical requirements for cardiac CT are widely available even in remote locations. 2
In this chapter, we begin with some definitions of “cardiac CT” to provide a basis for understanding its diagnostic capabilities and limitations. We describe the major functions of cardiac CT, including calcium scoring, CT coronary angiography, CT assessment of left ventricular function, and assessment of noncardiac causes of chest pain. We explore controversial areas of relative risk and benefit, comparing CT to other diagnostic modalities and strategies for evaluating ischemia and cardiac function. We specifically consider issues of emergency department length of stay, crowding, and cost for which CT has putative benefits. We weigh these potential advantages against radiation exposure, potential for unnecessary testing (and increased costs), and risk for false-positive test results that may ensue from widespread use of cardiac CT.