V.A. Khilko, L.A. Tyutin, N.P. Fadeev, A.V. Pozdnyakov, N.A. Kostenikov, V.Yu. Sukhov
(Saint Petersburg Research and Practice Neurosurgical Center, Municipal Multifield Hospital N2, Central Institute of Rentgenology and Radiology, Saint Petersburg)
Acute and chronic disorders of cerebral circulation, accompanied by high mortality and disability, are one of the most important medical and social problems of the XXI century.
Successful surgical treatment of these diseases is much dependent on determination of indications for an operation. It can be done with modern technical means of estimating volumetric blood flow and metabolism in zones of ischemic cerebral disorders.
A for our studies, estimation of regional cerebral circulation and brain metabolism was carried out with the help of such radionuclide methods as single-photon emission tomography (PET) and proton MR spectroscopy (+H MRS), which are simple, noninvasive and rather informative.
The most available apparatus for determining regional cerebral circulation was Apex SP-6 (Elscinit company).
Brain perfusion was studied with application of a radio preparation (99 mTc-Ceretec). Cerebral areas with perfusion of less than 18 ml/min/100 g and 19-35 ml/min/100 g were estimated as lacking vitality and ischemic respectively.
PET allowed to assess glucose metabolism in the brain and to obtain more reliable information on a degree of cerebral ischemia. We used Ecat Exact-47 tomograph (Siemens, Germany) and [18F] radio preparation (fluorodesoxyglucose [18F FDG]). Reduction of glucose metabolism in a zone of injury by 35-40% in comparison with an intact contralateral zone was considered to be hypometabolic changes. Reduction by more than 45-50% was estimated as irreversible changes.
Proton MR spectroscopy (+H MRS) made it possible to determine a character of biochemical changes in strokes of different etiology and to prognosticate versions of a disease course. We used Magnetom Vision 1.5 T apparatus (Siemens, Germany). We chose a single-voxel volume in the form of "a cube" (20´20´20 mm - 8 ml) and multi-voxel volume, embracing an area of cerebral ischemia and adjacent intact tissue. A state of a neuronal marker (NAA) in an area of stroke was estimated. It permitted to determine a stroke character. Information on lactate and lipids and a tendency of choline content changes helped to make suppositions, concerning a degree of cerebral tissue damage.
The abovementioned diagnostic modalities allow to determine indications for surgical treatment of stenosis and occlusion of carotid arteries in a cervical area more exactly.