Regional cerebral blood flow and metabolism in patients with chronic obstructive carotid disease

Regional cerebral blood flow (CBF), oxygen extraction fraction (OEF) and oxygen consumption (CMRO2) were studied by PET in 26 patients with chronic occlusion(s) or severe stenosis of the internal carotid or middle cerebral artery(ies) without a large (greater than 2 cm) infarction. Most of them showed a coupled decrease of CBF and CMRO2 in the internal carotid distribution. In 5 patients (19%), the CBF in the least perfused but structurally normal tissue was reduced to critically low values while maintaining CMRO2, considerably increasing OEF. Since detection of a lesion with hemodynamic insufficiency was important for the indication for an EC/IC bypass operation, only 19 per cent of the present series would have had an indication for surgery.