[Cerebral ischemia. Value of measurement of cerebral blood velocity and of oxygen consumption in positron emission tomography].

Simultaneous PET measurement of the regional cerebral blood flow (CBF), oxygen extraction (EO2) and cerebral oxygen consumption (CMRO2) demonstrated two important points for the therapeutic management of cerebral ischaemic accidents (CIA): very rapid alterations of the haemodynamic state (CBF and EO2) and the tissue consequences (CMRO2) to the acute phase of CIA and the considerable pathophysiological heterogeneity of these consequences. These two points explain the difficulties encountered in the development of anti-ischaemic treatments. They show the necessity of developing simple techniques which would allow real-time monitoring of cerebral haemodynamics and the development of lesions following CIA. PET also allowed the direct evaluation of the haemodynamic repercussions of carotid artery occlusion, which are much more severe than suggested by classical data and it is therefore possible that the real frequency of CIA of "haemodynamic" origin is severely underestimated.