Medical Imaging of Ischemic Stoke

Abstract

CT is the first tool for the diagnosis of acute infarction, but CT is not sensitive to detect early infarction. Several signs of early stages of MCA infarction are noted, including loss of insular ribbon sign, obscuration of lentiform nucleus sign, loss of gray–white matter contrast sign, effacement of cortical sulci sign, and bright MCA sign. The DWI of MRI can accurately diagnose large and small infarctions at a very early stage because the infarct area is cytotoxic edema with diffusion restriction, showing bright (hyperintense) in DWI. CT perfusion is a method to determine whether the infarction is in golden 6 h. Using parameters, such as CBF, CBV, MTT, and DT, can determine the core and penumbra of the hypoperfusion area to determine whether to perform IV thrombolysis and IA thrombectomy. Cerebral vein and venous sinus thrombosis may cause venous infarction edema similar to arterial infarction edema on CT. CT can identify the thrombus as an “empty delta sign.” MRI reveals that the venous infarction edema is cytotoxic edema in the middle and combines with peripheral vasogenic edema. The brain damage caused by CO poisoning is primarily in the bilateral globus pallidus, and severe poisoning may involve the centrum semiovale. These brain injuries are also bright in DWI. Moyamoya disease is stenosis and occlusion of the distal ICA with smoke-like collateral circulation vessels in the brain. In adults, it may present ICH and IVH and in children it may present ischemic infarction. Small vessel diseases include leukoaraiosis, microbleeds, and dilated Virchow–Robin spaces. Using variable pulse sequences, MRI is more sensitive than CT in diagnosing small vessel diseases.