^(18)F-FDGPET显像诊断老年性痴呆初步研究

The preliminary study of ^(18)F-FDGPET brain PET in diagnosis of Alzheimer's Disease

目的 探讨18F 脱氧葡萄糖 (FDG)PET显像诊断老年性痴呆 (AD)的影像特征和诊断标准。方法 静脉注射18F FDG后行脑断层显像 ,获得顶叶、颞叶、额叶单位面积放射性计数与小脑计数的比值 ,以此作为半定量指标。结果 12例正常人可见大脑皮质各叶、基底神经节、丘脑及小脑放射性分布均匀对称。 12例AD影像分为 3种 :双侧顶叶放射性减低 5例 ,双侧颞顶叶减低 4例 ,单侧颞顶叶减低 3例。半定量分析显示AD患者顶颞叶代谢显著低于正常人 ,并与痴呆程度相关。 11例非AD痴呆影像也分 3种 :多发性非对称性放射性减低 8例 ,双侧颞顶叶伴其他多灶性放射性减低 2例 ,显像正常 1例。MRI检查 10例AD可见颞叶、杏仁核、海马体积缩小 ;2例轻度AD虽有代谢减低 ,但MRI未见海马体积缩小。 10例非AD痴呆MRI可见脑内陈旧出血、梗死、软化灶等病灶 ,而这些表现AD患者未见到。结论 在MRI除外脑内结构损害病灶基础上 ,18F FDGPET发现双侧或单侧顶叶或颞顶叶代谢减低可诊断AD ;半定量分析有助于痴呆程度的评价。

Objective To investigate the imaging characteristics and diagnostic criteria of 18 F FDG brain PET in diagnosis of Alzheimer's disease (AD) Methods The study included 12 normal subjects, 12 patients with AD and 11 patients with non AD dementia 40 min after intravenous administration of 18 F FDG, brain scan was performed using Siemens ECAT 47 scanner The transaxial, coronal and sagittal images were then reconstructed by computer At the same time, semiquantitative analysis was also applied to help evaluation using the ratio of mean radioactivity of cerebral lobe to cerebellum (R cl/cb ) Results In normal subjects PET scan showed clear images of cerebral cortex, basal ganglia, thalamus and cerebellum with symmetrical distribution of radioactivity PET images from Alzheimer's disease patients were classified into 3 patterns: bilateral parietal hypometabolism in 5 cases, bilateral temporo parietal hypometabolism in 4 cases and unilateral temporo parietal hypometabolism in 3 cases The R cl/cb of AD patients in parietal and temporal lobe was significantly decreased than normal subjects (P<0 05) PET images from non AD dementia were also classified into 3 patterns; multiple and asymmetrical patch foci with decreased radioactivity in 8 cases, bilateral temporo parietal with diffuse cortical hypometabolism in 2 cases, and normal imaging in 1 case The hypometabolic involvement was found in accord with severity of dementia The R cl/cb was also reflecting the dementia degree Compared with MRI imaging, 12 patients with AD had cerebral hypometabolism but only 10 had hippocampus atrophy 10 patients with non AD dementia had local structural foci seen in MRI, including old hemorrhage, infarction and encephalomalacia, but these lesions were not found in AD Conclusions Based on excluding cerebral structural lesions which are better detected by MRI, bilateral or unilateral parietal or temporo parietal hypometabolism found in FDG PET can be considered indicative of Alzheimer's disease Semiquantitative analysis of the images yielded can help to evaluate the dementia degree