Prognostic aspects of single-photon emission tomography of the brain in surgical treatment of extracranial arteries stenosis

Brain tissue perfusion and blood content parameters were studied by single-photon emission computer-aided tomography at brain sites supplied with blood via extracranially stenosed cerebral artery for the evaluation of postoperative time course of neurologic deficit after carotid endarterectomy combined with internal carotid artery mouth plasty. Brain matter local blood content at sites to which blood is delivered via a stenosed vessel permits assessment of brain tissue viability in patients with stenosed extracranial cerebral vessels and prediction of the possibility of neurologic deficit regression resulting from radical angiosurgery. Brain blood content interhemispheric asymmetry index was prognostically the most valuable; it was calculated as a ratio of the maximal count to voxel in involved site and the contralateral intact site. Favourable neurologic time course was the most possible in patients with intact or increased brain matter blood content at sites that suffered brain circulation disturbances, manifested by indexes of cerebral blood content asymmetry equal or higher than 1.0. When this index was below 0.9, which was observed when brain ischemic involvement mass was over 55 g (52 cm³), angiosurgical treatment did not result in regression of neurologic deficit that occurred because of an acute disturbance of brain circulation.