A Comparison between

As GABA receptors are abundant in the cortex, specific radioligands to their subunits, which are benzodiazepine receptors (BZR), may be useful as indicators of neuronal integrity and as markers of irreversible damage. We investigated the relation between cerebral metabolic rate of oxygen (CMRO2) and binding potential of the BZR ligand [C] flumazenil using PET in patients with hemodynamic cerebral ischemia. The subjects consisted of 10 patients with severe stenosis or occlusion of either internal carotid or middle cerebral artery. Three regions of interest (ROI) were set on the cortex in the middle cerebral artery territory. Thirty ROIs were obtained in 10 patients. Semiquantitive values of CMRO2 and flumazenil binding potential to contralateral side were analyzed. In 26 ROIs of 30, flumazenil binding potential was correlated to CMRO2 (r=0.757, p<0.0001), but remaining 4 ROIs, flumazenil binding potential did not change whereas CMRO2 decreased. In conclusion, CMRO2 resembles flumazenil binding potential in its ability to detect irreversible damage of cortex with hemodynamic cerebral ischemia. However, several exception exists by the influence of diaschisis.