[Factors determining the therapeutic window in acute ischemic stroke: characteristics of PET studies]

To make a brief review of the use of PET in the study of patients with acute ischemic stroke.

In the cerebral cortex PET may be used to detect a series of changes which permit the definition of three types of patients with different prognoses. The patients of type 1 (severe fall in cerebral blood flow and CMRO2) have an unfavorable prognosis and do not benefit from fibrinolytic treatment and/or neuroprotection to assist recovery of areas of penumbra. Patients of type 2 (marked drop in cerebral blood flow with moderate reduction of CMRO2) have a doubtful prognosis and are those which, in theory, might benefit from fibronolytic and/or neuroprotector treatment to help recovery of zones of penumbra. The patients of type 3 (focal hyperperfusion with CMRO2 maintained) have a favorable spontaneous prognosis.

This technique also shows that the therapeutic window should be individually analyzed in each case. This data is of great interest when planning therapeutic clinical studies.