Medical Imaging of Cerebral Hemorrhagic Stroke

Abstract

Two types of hemorrhagic stroke include intracerebral (intraparenchymal) hemorrhage (ICH) and subarachnoid hemorrhage (SAH). The acute ICH shows hyperdensity on CT and can easily be diagnosed. In the subacute stage, the density of hematoma gradually decreases, and the brain edema around the hematoma becomes obvious. In the chronic stage, a linear cavity in the original ICH location is observed and associated with peripheral brain tissue atrophy. MRI is an auxiliary tool for diagnosing ICH. The evolution of ICH is complicated in MRI, and it is divided into five stages. ICH is most often caused by hypertension, and the locations are in deep areas, such as the putamen, thalamus, brainstem, and cerebellum. Lobar hemorrhage is primarily caused by amyloid angiopathy, AVM, and tumor bleeding. For the diagnosis of ICH, plain CT is usually sufficient. In young stroke and lobar hemorrhage, contrast-enhanced CT plus CTA and even DSA can be performed to find a vascular anomaly or others. Most spontaneous SAH is caused by the rupture (leakage) of an aneurysm. Most aneurysms are located in the circle of Willis. CTA can detect most of the aneurysms. In addition to SAH, 30% of aneurysm rupture may combine ICH. The ICH provides a valuable clue to surmise the location of aneurysms, such as if an ICH is in the frontal lobe or septum pellucidum, the aneurysm is in the ACoA; an ICH in the mesial temporal lobe, the aneurysm is in the ICA/PCoA; and a hematoma in Sylvian fissure, the aneurysm is in the bifurcation of MCA.