Which examination is most appropriate for diagnosing mediastinal masses?

A CT scan is the most appropriate examination for diagnosing mediastinal masses due to its superior imaging capabilities. It provides detailed cross-sectional images of the chest, allowing for better visualization of the mediastinum and the structures within it. The CT scan can reveal the size, location, and characteristics of the mass, which are critical for determining the further management and potential treatment options.

While a chest X-ray can provide initial information and may suggest the presence of a mass, it lacks the specificity and detail required for a thorough assessment. MRI, though useful in certain contexts, is less commonly used for mediastinal evaluation due to factors such as time constraints and the availability of CT imaging. Ultrasound is not an effective tool for assessing mediastinal masses because it does not penetrate through air-filled structures, such as the lungs, and therefore cannot provide the detailed information needed in this situation. Thus, the CT scan is the gold standard for this purpose, offering comprehensive details crucial for diagnosis and management.