摘要：

研究背景 后部皮质萎缩作为一种以皮质视觉障碍为首发症状的进展性神经变性病，具有临床少见、发病较早、临床表现特殊、早期MRI表现不典型等特点，明确诊断困难。本研究对MRI表现不明显的后部皮质萎缩患者行¹⁸F-脱氧葡萄糖（¹⁸F-FDG）PET 和¹¹C-匹兹堡复合物B（¹¹C-PIB）PET 显像，探讨PET 显像在后部皮质萎缩早期诊断中的价值。方法 选择5 例MRI 无明显顶枕叶皮质萎缩的后部皮质萎缩患者，分别采用简易智能状态检查量表、蒙特利尔认知评价量表、日常生活活动能力量表和画钟测验评价认知功能，¹⁸F-FDG PET 和¹¹C-PIB PET 显像观察大脑后部皮质葡萄糖代谢和灌注情况。结果 神经心理学测验提示5 例患者书写能力、计算力、视空间能力、执行功能均明显受损并色觉测试异常。MRI检查后皮质萎缩评分左侧0 ~ 2 分、平均1 分，右侧0 ~ 1 分、平均0.80 分；内侧颞叶萎缩评分左侧1 ~ 3 分、平均1.80 分，右侧1 ~ 4 分、平均2 分；脑室扩大评分左侧1 ~ 2 分、平均1.80 分，右侧1 ~ 2 分、平均1.60 分。¹⁸F-FDG PET 显示，双侧颞顶枕联合区皮质、楔前叶和扣带回葡萄糖代谢显著降低，额叶和皮质下结构少量降低；¹¹C-PIB PET 可见双侧额颞顶枕联合区皮质放射性¹¹C-PIB 滞留、小脑皮质廓清。结论 对于MRI 显示顶枕叶皮质萎缩不明显的后部皮质萎缩患者，¹⁸F-FDG PET 联合¹¹C-PIB PET 显像具有一定早期诊断价值。

关键词: 痴呆, 大脑皮质, 萎缩, 神经心理学测验, 正电子发射断层显像术

Abstract:

Background  Posterior cortical atrophy (PCA) is a kind of progressive neurodegenerative disease with cortical visual impairment as the first symptom. Because of rare clinical incidence, early onset age, special clinical symptoms and unobvious MRI abnormality, the definitive diagnosis of PCA is difficult. This study used ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) PET and ¹¹C-Pittsburgh compound B (¹¹C-PIB) PET for PCA patients with unobvious MRI abnormality, so as to discuss the value of PET in the early diagnosis of PCA.  Methods  Five patients diagnosed as PCA in our hospital between April 2012 and March 2015 were enrolled in this study. Cognitive function was measured by Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Activities of Daily Living (ADL) and Clock Drawing Test (CDT). Brain MRI, ¹⁸F-FDG PET and ¹¹C-PIB PET were performed to analyze glucose metabolism and perfusion of posterior cortex.  Results Neuropsychological tests revealed that the ability of writing, calculating, visuospatial and executive function of all these patients were impaired. Color vision tests showed abnormal results. MRI showed that the posterior atrophy (PA) scores were 0-2 (average 1) on the left side and 0-1 (average 0.80) on the right side. The medial temporal atrophy (MTA) scores were 1-3 (average 1.80) on the left side and 1-4 (average 2) on the right side. The ventricular enlargement (VE) scores were 1-2 (average 1.80) on the left side and 1-2 (average 1.60) on the right side. ¹⁸F-FDG PET showed glucose metabolism decreased obviously on bilateral temporo-parieto-occipital cortex, precuneus and cingulate gyrus, and slightly on frontal lobes and subcortical structure. ¹¹C-PIB PET showed radioactive ¹¹C-PIB deposition on bilateral frontal, temporal, parietal and occipital cortex, and the outline of cerebellar cortex was clear.  Conclusions  For PCA patients whose parietal and occipital cortical atrophy is not obvious on MRI, ¹⁸F-FDG PET combined with ¹¹C-PIB PET plays an important role in early diagnosis.

Key words: Dementia, Cerebral cortex, Atrophy, Neuropsychological tests, Positron-emission tomography