Development of the noninvasive brain function diagnostic procedure using magnetoencephalography for the purpose of foreseeing the onset of cerebral ischemia

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Clinical researches of MEG and PETWe performed 015 gas PET, which measured cerebral blood flow(CBF) and oxygen extraction fraction(OEF), and magnetoencephalography which measured evoked magnetic field for cerebrovascular disorder 25 examples. Furthermore, we measured spontaneous magnetic field of brain and analyzed the frequency using spatial filter technique(beam former). The results showed correlation of dipole moment of N20m and OEF. Beam former showed 0 and 6 activity in the ischemic area. Especialy, 0 activity correlated OEF increased lesion.Fundamental researches of MEGWe developed SQUID magneto meter array of nine channels which did integration on a silicon chip for the purpose of small animal's magnetic field. (the sensor array have nine 2.5mm (I) SQUID magneto meters arranged in the shape of 3 X 3 matrices every 2.75mm, and total size is 10 X 10mm.). We set this magnetometor in small shield box which set in a shield room. We could reproducibility measure visual evoked field and auditory evoked field of rat brain using this instrument, but could not detect somatosensory evoked field.Fundamental researches of PETWe made a cerebral ischemia model of rat brain and measured carbohydrate metabolism using micro PET. We compared PET image with autoradiograph in small ischemic area of middle cerebral artery, and PET could enough detect its lesion. We measured brain glucose metabolism by electric stimulation of peripheral nerve, but were not able to detect clear change. However, the lesion was depicted in autoradiograph distinctly. It is thought that there is limitation for analysis of rat brain in micro PET with an aspect of quantitative evaluation..