Learning to interpret the extracardiac findings on coronary CT angiography examinations

Abstract

Coronary computed tomography angiography (CTA) plays an important role in the identification of coronary artery disease in low- to intermediate-risk patients. Even with a “restrictive” field of view, coronary CTA data sets will include visualization of structures adjacent to the heart, including the thoracic great vessels, pericardium, mediastinum, lungs, and bones. CT images enable detailed assessment of these structures, at times identifying a potential noncoronary cause of the patient’s presenting symptom. The reported incidence of extracardiac findings on coronary CTA is as high as 53%–67%. Complete evaluation of the examination requires scrutiny of the soft tissues, lung tissues, and bones, both in the chest and adjacent abdomen. It is important to adjust the CT window display settings at various stages of the interpretation process to evaluate all potential extracardiac disease. Although in-depth radiology training would be required to correctly identify and interpret all anomalies, this article serves as an overview and guide to evaluation of the extracardiac structures included on a coronary CTA examination. Correct interpretation of extracardiac findings is critical because a false positive interpretation can lead to unnecessary testing and treatment that can be as harmful as a false negative interpretation. Most importantly, if the cardiac findings do not explain the patient’s symptoms, an alternative cause should be specifically sought to appropriately manage the patient.