Which diagnostic study is preferred for a patient suspected of having an acute aortic dissection?

A computed tomography (CT) scan is the preferred diagnostic study for a patient suspected of having an acute aortic dissection due to its rapid availability and ability to provide detailed images of the aorta and surrounding structures. CT angiography, in particular, is highly sensitive and specific for detecting aortic dissections and can quickly show any abnormalities such as a false lumen or involvement of branch vessels.

In an emergency setting, the speed of a CT scan makes it an ideal choice, as it can be performed quickly and provides crucial information to guide management decisions. The CT scan also allows for evaluation of the entire thoracic and abdominal aorta, which can be essential in identifying the extent of the dissection.

Other imaging modalities like a transthoracic echocardiogram can be useful, particularly for identifying pericardial effusion, but it may not provide comprehensive views of the aorta. Magnetic resonance imaging offers excellent soft tissue contrast and visualization but is less commonly used in acute settings due to longer acquisition times and limited availability. Cardiac catheterization is not typically employed for diagnosing aortic dissection since it does not adequately visualize the aorta itself and carries potential risks for the patient.