Comprehensive CT Imaging in Acute Chest Pain

Abstract

Triple rule-out (TRO) CT simultaneously evaluates the coronary arteries, aorta and pulmonary arteries for the patient presenting with acute chest pain in the emergency department. Compared to dedicated coronary CT angiography (cCTA), TRO CT requires slightly more intravenous contrast and a higher radiation dose. Appropriate patient selection is essential. TRO CT is most appropriate for patients at low to intermediate risk for acute coronary syndrome and in whom alternative diagnoses, such as pulmonary embolism or acute aortic pathology, are being considered. Adequate patient selection, preparation, premedication, and monitoring ensure a high-quality diagnostic study. The major differences between TRO CT and dedicated cCTA are scan length and injection technique. Compared to cCTA, where images are obtained between the carina and diaphragm, TRO CT must include the entire thoracic aorta and the pulmonary arteries. Injection protocols are tailored to provide high levels of arterial enhancement in the left- (coronary arteries and aorta) and right-sided circulations (pulmonary arteries). Different strategies may be employed to limit radiation exposure, including electrocardiogram (ECG) tube current modulation and prospective ECG gating. When performed with careful attention to technique, TRO CT provides high-quality diagnostic opacification of the coronary arteries, aorta and pulmonary arteries equal to that of dedicated CT angiography. A negative study allows for the safe and rapid discharge from the emergency department and a reduction in subsequent testing.