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Cardiac Imaging

E3142. The Importance of Aortic Opacification in CT Pulmonary Angiogram (CTPA)

Kang J,  Nguyen E,  Hsu J. Kaiser Permanente Los Angeles Medical Center, Los Angeles, United States

Address correspondence to J. Kang (j319kang@gmail.com)

Background Information: Chest pain is common, representing up to 40% of all emergency department visits in the United States. The most emergent causes of chest pain are well known to be pulmonary embolism (PE), acute aortic syndrome (AAS), and acute coronary syndrome (ACS), each with differing clinical presentations. Chest pain may be atypical and often confuses the clinical picture. In a retrospective trial performed in 2015 with 457 patients, the prevalence of ACS and AAS was found to be 5.5% and 0.5%, respectively, in those who were clinically suspected to have a PE. The prevalence of ACS and PE was 18.3% and 5.6% among those who were suspected to be suffering from AAS. Rarely, these diagnoses may even present simultaneously in the same patient.

Educational Goals/Teaching Points: The aim of this exhibit is to present cases in which aortic or left ventricular pathology was missed or not well-visualized on CT pulmonary angiograms (CTPA) that were timed to only opacify the pulmonary arteries. We will perform a comprehensive review of the current literature regarding the incidence of aortic or left ventricular pathology in patients presenting with chest pain. In addition, we will discuss the importance of opacifying the aorta when performing a CTPA as well as the advantages and disadvantages of different protocols for performing CTPA, including the role of gating and triple rule-out (TRO) protocol.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: There is a slew of available CT protocols for the evaluation of chest pain that include dedicated CT pulmonary angiogram, CT aortic angiogram, CT coronary angiogram, and “triple rule-out” protocol. Techniques that can be utilized to better opacify the aorta include moving the ROI from the main pulmonary trunk to the ascending aorta, increasing the contrast bolus, or employing a dual bolus injection technique.

Conclusion: Potentially life-threatening pathology such as aortic dissection or intramural thrombosis can be missed due to poor opacification of the aorta and left ventricle on a CTPA. In our institution, poor opacification of the aorta or left ventricle allowed such pathologies to be missed. It can also be argued that simultaneous opacification of the aorta and pulmonary arteries does not significantly lower the sensitivity for detecting PE. Thus, though the incidence of AAS is low in those suspected of suffering from PE, it may be argued that opacification of the aorta is appropriate in angiographic CT studies for the evaluation of chest pain.