What is a key distinguishing factor of hemorrhagic stroke on imaging?

The key distinguishing factor of hemorrhagic stroke on imaging is the presence of blood in the cranial cavity. In the context of hemorrhagic stroke, imaging studies such as CT scans or MRIs reveal areas where blood has escaped from blood vessels into the surrounding brain tissue or the ventricles. This is indicative of a hemorrhage, which can occur due to various causes, such as the rupture of an aneurysm or an arteriovenous malformation. The identification of this blood allows healthcare professionals to distinguish hemorrhagic strokes from ischemic strokes, where there is typically no presence of blood but rather regions of infarction due to lack of blood supply.

The presence of a clot is more characteristic of ischemic strokes, where a clot obstructs blood flow to a part of the brain. Enlargement of the brain tissue and loss of brain matter can occur in various types of strokes but are not specific to hemorrhagic strokes. Instead, these findings are more associated with the effects of brain injury or damage from prolonged ischemia. Therefore, the presence of blood in the cranial cavity is the crucial factor that signifies hemorrhagic stroke on imaging studies.