阿尔茨海默病患者扣带回后部各向异性与葡萄糖代谢关系研究

Correlation between anisotropy and glucose metabolism rate in the posterior cingulated gyrus of patients with Alzheimer's disease

目的用磁共振扩散张量成像(DTI)研究阿尔茨海默病患者扣带回后部各向异性损害的特点及其与葡萄糖代谢改变的关系。方法对16例AD患者和12例年龄及性别相当的健康老年人行DTI、T1液体衰减反转恢复序列(FLAIR)及T2-FLAIR检查,测量扣带回后部部分各向异性分数值(FA)和平均弥散度(MD),分析FA、MD值与MMSE评分之间的相关关系;正电子发射计算机断层摄影(PET)观察扣带回后部葡萄糖代谢改变,并分析FA、MD与葡萄糖代谢改变的关系。结果与对照组相比,AD患者扣带回后部的FA值显著降低(P=0.018),MD值显著升高(P=0.020),葡萄糖代谢率显著降低(P=0.020);MD值与葡萄糖代谢率呈负相关(r=-0.700,P=0.05),而FA值与葡萄糖代谢率无相关关系(r=-0.054,P=0.844)。结论AD患者表现为扣带回后部各向异性损害,且损害程度与葡萄糖代谢率呈负相关;这种损害反应了AD病理机制中皮质-皮质及皮质-皮质下联系的丢失;扣带回后部FA、MD值可以用来监测疾病的进展情况及评价AD治疗药物的临床疗效。

Objective To investigate anisotropy damage of posterior cingulate gyrus and its correlation to glucose metabolism rate（rCMRglc） in patients with Alzheimer＇s disease by using the diffusion tensor imaging （DTI） and PET. Methods Diffusion tensor imaging, as well as T1 -fluid attenuated inversion recovery （FLAIR） and T2-FLAIR, was performed in probable Alzheimer＇s disease patients and sex and age matched healthy volunteers to measure the fractional anisotropy （FA） ,mean diffusivity （MD） in the posterior cingulate gyrus. PET was used to observe the rCMRglc in the posterior cingulated gyrus. Correlation analysis was applied to reveal the relationship between the FA and MD values and the rCMRglc. Results In contrast to healthy controls, patients with AD had a lower FA, rCMRglc and higher MD in the posterior cingulate gyrus. Besides, MD of AD patients was strongly negative correlated with rCMRglc, but FA was no correlation with rCMRglc. Conclusion The posterior cingulated gyrus of patients with Alzheimer＇s disease is impaired and the extent of damage should has a strong correlation with rCMRglc. The selective impairment might reflect the cortico-cortical and cortico-subcortical disconnections in the pathomechanism of Alzheimer＇s disease. DTI technique should be used to monitor the disease progression and as a surrogate marker for evaluation of drug efficacy in vivo.