Investigation of Senile Dementia with PET and MRI

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In this research, we tried to extract the characters of changes from normal aging through senile dementia. The results obtained were as follows.(1) Cerebral metabolism and aging changes on MRI.We investigated the relationship between cerebral blood flow by PET and the periventricular hyperintensity (PVH) which is an aging change on MRI and found decreased cerebral blood flow in cases of severe PVH.(2) Characters of formal changes in multi-infarct dementia (MID) on X-CT.Brain atrophy progresses during aging. We revealed the characteristic widening of the inferior horns of the lateral ventricles in cases of MID unlike in normal aging.(3) Regional cerebral glucose metabolism on PET in senile dementia of Alzheimer type (SDAT) and MID.We assumed the common basis of functional changes in SDAT and MID which have different pathogenesis but have same clinical symptoms. We studied these functional abnormalities from the aspect of regional cerebral glucose metabolism and found common hypometabolism of glucose in the association corteces of dementia cases.(4) Correlation between widening of the inferior horns of the lateral ventricles and decrease of regional cerebral glucose metabolism.We investigated the relationship between the size of ventricular system and regional cerebral glucose metabolism. The results showed that widening of the inferior horns of the lateral ventricles was strongly correlated with decrease of regional cerebral glucose metabolism in cerebral corteces regardless of the type of dementia, MID or SDAT.These results suggested that dementia was closely related to the changes in hippocampus and amygdala which constitutes the medial aspect of the inferior horns. Therefore we emphasize here the great necessity for studies of the limbic system as a focus in the investigation of dementia.