Final answer:
MRI and CT are primary imaging modalities for diagnosing aortic dissection and pulmonary embolism, with CT being preferred in acute cases due to its speed and resolution.
Step-by-step explanation:
In the context of diagnosing conditions such as suspected aortic dissection or pulmonary embolism, Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scanning are pivotal imaging modalities. An MRI, especially when used with a contrast agent, alters the magnetic properties of water in cells to produce detailed images of soft tissues, which can be crucial for identifying aortic dissection.
Additionally, while Positron Emission Tomography (PET) scans are less commonly used in acute scenarios like aortic dissection or pulmonary embolism, they offer unique insights into physiological activities and blood flow within various organs. This technique employs radiopharmaceuticals to investigate metabolic functions, which can support the diagnosis of a broad range of conditions.