在AD病程中海马代谢水平与体积改变的研究

The study of hippocampal metabolites level and volumetric changes in AD

目的:探讨阿尔茨海默病(AD)、轻度认知功能障碍(MCI)以及正常老年人(NC)海马代谢与海马体积的改变及其关系。方法:收集南京大学医学院附属鼓楼医院神经内科记忆门诊MCI患者30例,AD患者20例,同时入组30例性别、年龄、受教育程度匹配的正常老年人对照。使用Achieva 3.0 T TX双梯度双射频源磁共振成像系统,SENSE-8-HEAD线圈。所有被试者行海马结构和海马区多体素2D-PRESS1H-MRS检查。采用Free Sur Fer计算海马体积。Philips Achieva MR后处理工作站对波谱数据进行处理,将海马分为头、体、尾3部分,计算其N-乙酰天冬氨酸(NAA)/肌酸(Cr)、肌醇(m I)/Cr的值。比较AD、MCI、NC 3组间海马体积差异、各代谢物比例差异,行体积与代谢指标的相关性分析。结果:AD患者两侧海马体积较MCI、NC组显著缩小(P<0.05),海马体积在NC与MCI两组中差异无统计学意义(P>0.05);AD组NAA/Cr值在右侧海马(头部)、左侧海马(整体、头、体、尾部)较MCI、NC组显著降低(P<0.05),m I/Cr值在右侧海马(整体、头、体、尾部)、左侧海马(整体、头、尾巴)显著升高(P<0.05)。MCI组和NC比较,MCI患者左侧海马头NAA/Cr值显著降低、m I/Cr组值显著升高(P<0.05)。两侧海马体积与MMSE、MOCA分数呈显著正相关(P<0.05);左侧海马体积与左侧海马头NAA/Cr值呈显著正相关,与m I/Cr值呈显著负相关(P<0.05)。结论:双侧海马体积在AD患者中显著缩小,而MCI阶段海马体积萎缩不明显,但海马NAA/Cr值及m I/Cr在MCI阶段即有早期改变,说明海马代谢改变可能先于其结构的变化。MCI阶段中NAA/Cr、m I/Cr值的改变可能是MCI向AD发展的一个早期指标。

Objective： To investigate the metabolic and volume changes of hippocampus in Alzheimer disease（ AD）,mild cognitive impairment（ MCI） and normal controls（ NC）. Methods： AD（ n = 20） and MCI（ n = 30）patients were recruited at the Memory Clinic of Neurology Department in Nanjing Drum Tower Hospital,and ageand sex-matched NC（ n = 30） were identified. MRI examinations were performed at 3 Tesla using an SENSE-8-channel phased array coil（ Achieva 3. 0 T TX dual gradient and dual-source parallel RF excitation and transmission technology,Philips Medical Systems,The Netherlands）. The structural MRI and 2D-PRESS1 H MRS data were acquired and preprocessed. Hippocampal volume was calculated by Free Sur Fer. And the ratio of N-acetylaspartate（ NAA） /creatine（ Cr） and myoinositol（ m I） /Cr in hippocampal subfields（ head,body and tail） were calculated in Philips Work-station. The hippocampal volume and metabolite ratios were compared in AD,MCI and NC group.And correlation analysis between volume and metabolite ratios was also included in this study. Results： Bilateral hippocampal volumes were significantly reduced in AD compared with MCI and NC（ P〈0. 05）. There were no significant differences between MCI and NC in bilateral hippocampal volumes（ P〉0. 05）. Compared with MCI and NC,NAA / Cr ratio in AD was significantly decreased in right hippocampus（ head） and left hippocampus（ head,body and tail）,m I / Cr ratio in AD was significantly increased in left hippocampus（ head and tail） and right hippocampus（ head,body and tail）（ P〈0. 05）. Compared with NC,MCI patients showed significantly decreased NAA / Cr ratio and increased m I / Cr ratio in left hippocampus head（ P〈0. 05）. There were significant positive correlations between bilateral hippocampal volumes and MMSE,Mo CA score（ P〈0. 05）. Left hippocampal volume was positively correlated with NAA / Cr ratio and negatively correlated with m I / Cr ratio in left hippocampal head（ P〈0. 05）. Conclusion： Bilateral hippocampal volumes significantly reduce in AD. Hippocampal atrophy seems not obvious in MCI stage while changes of NAA / Cr and m I / Cr ratio in left hippocampal head could be detected,indicating that hippocampal metabolic changes might be earlier than structural changes in MCI. And hippocampal metabolic changes might be an early biomarker to detect AD dementia.