摘要：

目的 探讨¹⁸F-FDG PET 显像在阿尔茨海默病与额颞叶痴呆鉴别诊断中的应用价值。方法 对临床明确诊断的阿尔茨海默病（20 例）和行为异常型额颞叶痴呆（20 例）患者的¹⁸F-FDG PET 显像资料进行回顾，分析两组患者皮质代谢降低脑区间的差异。结果 视觉分析显示，两组患者均表现为皮质代谢降低，阿尔茨海默病患者以双侧颞顶叶和后扣带回代谢降低明显，以及部分额叶皮质代谢降低，而基底节和丘脑不受累，18/20 患者双侧大脑半球皮质代谢降低范围和程度基本对称；额颞叶痴呆患者额叶和前颞叶皮质代谢均降低，其中11 例同时伴部分顶叶皮质和基底节、丘脑等皮质下核团不同程度降低，16/20 患者双侧大脑半球代谢降低程度和范围明显不对称，4 例以右侧为主、12 例以左侧为主。结论 由于¹⁸F-FDG PET 显像所显示的阿尔茨海默病和额颞叶痴呆患者之皮质代谢降低图型不同，故具有较好的鉴别诊断价值。

关键词: 阿尔茨海默病, 痴呆, 正电子发射断层显像术

Abstract:

Objective  To delineate the pattern of reduction of cerebral glucose metabolism in patients with Alzheimer's disease (AD) and frontotemporal dementia (FTD) and investigate the value of ¹⁸F-FDG PET in the differential diagnosis.  Methods  Twenty patients with FTD (behavioral variant) and 20 AD patients underwent ¹⁸F-FDG PET scanning. All the images were compared with that from 20 healthy age-matched control subjects on a voxel-based analysis (VBA) using SPM5. Visual analyses of ¹⁸F-FDG PET were performed by 2 independent nuclear medicine specialists who were blinded to the clinical background. Results 1) The PET scans of all the patients in 2 groups presented impairment of cortical metabolism. 2) Subjects with AD showed hypometabolism in the bilateral temporoparietal association cortex and posterior cingulate cortex, and hypometabolim in part of bilateral frontal lobes was observed in patients with progression. The metabolic activity was relatively kept in the primary motor-sensor cortex, occipital lobes and subcortical structures (basal ganglia and thalamus). The asymmetric hemispheric hypometabolic involvement was rare and observed in only 2 of 20 cases. 3) Subjects with FTD showed a significant
hypometabolism of the frontal lobes and anterior temporal lobes, accompanied by mild to moderate reductions in glucose metabolism in parietal cortices and subcortical structures. The asymmetric hemispheric hypometabolic involvement was commonly observed in 16 of 20 cases with right-dominant type in 4 of 16 cases and left-dominant type in 12 cases.  Conclusions  ¹⁸F-FDG PET is a reliable diagnostic test in distinguishing FTD from AD due to the sharp contrast pattern of cerebral glucose hypometabolism.

Key words: Alzheimer disease, Dementia, Positron-emission tomography