Investigation of Senile Dementia with PET and MRI

在本研究中，我们试图从正常衰老到老年性痴呆过程中提取变化的特征。结果如下：(1)脑代谢和年龄的变化。我们用正电子发射计算机断层扫描(PET)研究了脑血流变化与脑室周围高信号(PVH)的关系，发现重度PVH患者脑血流量减少。(2)多梗死性痴呆(MID)在X-CT上的形态改变特征，脑萎缩随年龄的增加而发展。揭示了不同于正常衰老的MID患者侧脑室下角的特征性增宽。(3)阿尔茨海默型和MID老年性痴呆患者脑部局部葡萄糖代谢的PET表现，推测两者发病机制不同，但临床症状相同。我们从局部脑葡萄糖代谢的角度对这些功能异常进行了研究，发现痴呆患者的相关脑区普遍存在葡萄糖代谢低下。(4)侧脑室下角增宽与局部脑葡萄糖代谢降低的相关性。结果表明，无论痴呆类型、MID或SDAT，侧脑室下角的增宽与大脑皮质局部葡萄糖代谢的降低密切相关，提示痴呆与构成下角内侧的海马区和杏仁体的变化密切相关。因此，我们在这里强调，作为痴呆症研究重点的边缘系统的研究是非常必要的。

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.