What is the fogging effect on CT imaging in the context of cerebral infarction, and when does it typically occur?

The fogging effect is a CT imaging phenomenon that occurs during the second week after a cerebral infarction. Initially, the infarcted area appears hypodense due to cerebral edema. As the edema and mass effect subside, proteins from cell lysis accumulate, causing the infarcted region to temporarily regain a normal appearance on CT, potentially obscuring the diagnosis. Key diagnostic features include the transient normalization of brain density, which can be mistaken for resolution of the infarct. Clinicians should be aware that this is a temporary phase and not indicative of true recovery.