Appearance of cerebral infarct fogging on CT perfusion

Fogging is a deceptive phenomenon that can partially or completely obscure a subacute infarct on noncontrast head CT. We present the appearance of infarct fogging on CT perfusion through 3 cases. At time of fogging, the subacute infarctions demonstrated variable mean transit time with increased cerebral blood volume and cerebral blood flow on CT perfusion. Fogging occurred within 6-10 days, sooner than the previously described 2-3 weeks in classic fogging. At time of fogging, CT perfusion demonstrated a "luxury-like" perfusion pattern and augmented the identification of the true extent of the infarction at time of fogging.