^(18)F-FDGPET脑显像对AD的诊断和分度

Degree Evaluation of Dementia of Alzheimer Disease with ^(18)F-FDG-PET

为探讨18F FDG(脱氧萄葡糖 )PET脑显像对Alzheimer病 (AD)的诊断和评价程度的标准 ,对AD组患者和正常老年组行静脉注射18F FDG后行PET脑断层显像 ,求出双侧额叶、顶叶、颞叶、枕叶、小脑皮质、基底节和丘脑的单位容积平均计数值 ,然后计算出各结构计数与小脑计数的比值。结果显示 ,正常对照组 ( 1 9例 )大脑各叶皮质、基底节和丘脑的计数分别与小脑计数的比值相当稳定 ,变异范围较窄 ,变异系数 2 .78%～ 8.95 %。以正常对照组顶叶、额叶、颞叶皮质与小脑计数比值的均数减去 2个标准差作为判断代谢异常减低的界值 ,则轻度、中度、重度AD患者的灵敏度分别为 6 6 .7% ( 4 / 6 ) ,85 .7% ( 6 / 7) ,1 0 0 % ( 4 / 4) ;正常对照组无 1例被误诊为AD ,特异性为 1 0 0 %。 1 7例AD患者大脑皮质放射性减低的范围随痴呆程度加重而扩大。轻度AD只有顶叶受累 ,中度和重度AD颞叶和额叶也受累 ,其中左额叶与小脑的计数比值减低程度是区别中度和重度AD的重要指标。结果表明 ,将顶叶、额叶、颞叶与小脑计数比值减低的范围和程度相结合 ,可以诊断AD并对AD痴呆程度做出较准确的评价。

The study explored the diagnosis standard to evaluate the degree of dementia of Alzheimer disease(AD) according to the comparison between AD patients and the normal. PET scan was performed after 40 minutes of injection of 18 F-FDG. The mean counts of bilateral frontal, parietal, temporal, occipital lobe, cerebellum, basal ganglion and the ratio of the above brain lobes via cerebellum were calculated in both AD patients and the normal. The counts ratio of the cerebral lobes, basal ganglion and thalamus via cerebellum was quite stable in the normal, with varying coeffient ranging from 2.78% to 8.95% . The AD patient's hypometabolism was judged according to the normal's standard with mean minus 2 s. The result showed that 4 out of 6 belonged to the mild , 6 out of 7 were middle, 4 out of 4 were severe in the AD patients. At the same time, the specific of the normal was 100%. The range of hypometabolism increased with the severity degree of dementia in 17 AD cases. There was hypometabolism only in the parietal in the mild cases, but hypometabolism occurred not only in the parietal but also in the temporal and the frontal in the middle and severe AD cases. The counts ratio between the left frontal lobe via the cerebellum was a very important index to distinguish between the middle AD patients and severe AD ones according to the degree of hypometabolism. Combining the hypometabolism scope with hypometabolism degree of counts ratio of the parietal, frontal and temporal lobes via the cerebellum could make the diagnosis of AD and evaluate the degree of dementia in a better way.