What imaging modality is primarily used to differentiate between ischemic and hemorrhagic strokes?

Non-contrast computed tomography (CT) is the primary imaging modality used to differentiate between ischemic and hemorrhagic strokes due to its rapid availability and effectiveness in acute settings. In the case of a hemorrhagic stroke, non-contrast CT can quickly detect the presence of blood in the brain tissue or within the ventricular system, allowing for immediate diagnosis and management.

Ischemic strokes, on the other hand, may not show up immediately on a non-contrast CT, especially in the early stages, but non-contrast CT is still crucial in ruling out hemorrhage, which significantly affects treatment decisions. When a patient presents with symptoms of a stroke, immediate imaging with non-contrast CT is a standard protocol to ensure that any hemorrhagic component is identified before initiating treatments that may exacerbate bleeding, such as thrombolysis.

Other imaging modalities like MRI or CT angiography provide additional details but are not as readily available in emergency settings and may not be performed as quickly as non-contrast CT. While MRI can be more sensitive in detecting early ischemic changes, it is not typically used as the first-line imaging in acute stroke evaluation due to longer acquisition times and the need for patient stability. PET scans are primarily used in research and are not