[Tomographic study in humans of blood flow and oxygen consumption of the brain by continuous inhalation of oxygen 15. Preliminary findings in cerebral ischemic accidents].

Transverse axial tomographic imaging of regional cerebral blood flow (rCBF) and regional oxygen extraction fraction (rOEF) were obtained in 13 patients hospitalizedfor ischemic strokes (eleven middle cerebral artery territory infarcts, one capsular or pontine lacune, one transient hemispheric attack) by continuous inhalation of 15O2 and C15O2 to equilibrium and exclusive detection of the gamma rays emitted in coincidence by means of a tomograph for positron emitting agents. In the transient ischemic attack and in the case of lacune the rCBF and the rOEF images were found to be normal, and they were abnormal in all cases of middle cerebral artery territory infarcts. In recent infarcts, rOEF was always strikingly decreased in the clinically suspected area, whilst the rCBF was either decreased, normal or increased. In infarcts older than 30 days rCBF was always clearly decreased over the clinically suspected area whilst rOEF was in most cases normal or only slightly decreased. These results are briefly discussed. Some practical and theoretical limitations of this method are mentioned. The potential of the present technique appears great however, since it is possible to simultaneously visualize in tomographic fashion the blood flow and the oxygen metabolism in areas of the brain that are of small volume, and however deep they are. A quantification of these parameters is presently under investigation, as well as the verification of the theoretical model on which such method is based. The non-invasiveness of the present method, the feasibility of repeating it at regular intervals of time, and the possibility of measuring the immediate effects of a given therapeutic mode on the regional metabolism of brain all constitute further advantages whose action apply preeminently in the field of the cerebral ischemic diseases.