轻度认知功能障碍11C-PIB PET连续动态显像结果分析

 为探讨轻度认知功能障碍（MCI）患者碳-11标记的匹兹堡化合物B（11C-PIB）正电子放射断层摄影术（PET）显像的特点，评价MCI患者11C-PIB PET脑显像的临床价值，严格筛选3组受试者：MCI患者8例，阿尔茨海默病（AD）对照组6例，健康对照（HC）组7例。每位受试者均采用连续动态采集程序采集脑PET图像。通过视觉分析各组受试者的图像，总结成像特点。采用感兴趣区域（ROI）方法划取大脑皮层各叶和皮层下核团，得出各个脑区不同时间点的标准吸收值（SUV），根据SUV绘出时间-放射性曲线。并选取45min时间点的SUV，计算出45min时各脑区与小脑的SUV比值并进行统计分析。结果发现，MCI组中一部分受试者PET图像特点与HC组相似；脑内放射性清除较快，而另外一部分受试者的脑内放射性清除则较慢。将MCI按照显像结果分为AD类似组及HC类似组进行分析后发现，AD类似组与AD组之间的清除率及脑区/小脑比值相比差异无统计学意义，而AD类似组与HC组之间的结果比较类似于AD组与HC组的比较结果。HC类似组与HC组之间的清除率及脑区/小脑比值相比差异无统计学意义，而HC类似组与AD组之间的结果比较则类似于HC组与AD组的比较结果。11C-PIB PET脑显像在不同MCI患者脑内的显像特点不同，因而有可能成为判断MCI预后的一种方法。

Dynamic Imaging of Mild Cognitive Impairment with 11C-PIB

The early diagnosis and treatment is very important for patients with Alzheimer's Disease (AD), which can be progressed from Mild Cognitive Impairment (MCI). The aims of this study include: (1) to determine the localization and the load of the beta-amyloid protein in the brains of MCI patients in vivo using 11C-PIB PET dynamic imaging; (2) to evaluate the clinical value of 11C-PIB PET imaging in MCI. 21 subjects, which were divided into three groups: 8 patients with MCI, 6 with AD, and 7 as Health Control (HC). All patients underwent sequential emission PET scans of brain after 11C-PIB administration. All 11C-PIB PET images were visually interpreted and analyzed by the Region of Interest (ROI) method. The attenuation-corrected PET images were semi-quantitatively analyzed using Standardized Uptake Value (SUV). Dynamic SUV data and curves were obtained as a function of time from 0 to 55 minutes of post-injection time. The ratio of radioactivity clearance and ratio of SUV of targeted brain regions vs cerebellum at 45min were calculated for statistical analysis. The dynamic images show that 11C-PIB passes cross the blood-brain barrier very rapidly, and clears rapidly in healthy brain. The results of applying the visual and ROI method indicate that AD patients typically show marked retention of 11C-PIB in related cortex where a large amount of amyloid is deposited. In MCI patients, the PET image of some patients are HC-like, and others are AD-like. Therefore, the MCI patients can be divided into 2 groups (HC-like group and AD-like group) for analysis, and the visual interpretations are consistent with the statistical analysis results. There are no significant difference observed in the data between HC-like group and HC group, and between AD-like group and AD group, respectively. It is concluded that 11C-PIB PET imaging can provide reliable quantitative information about beta-amyloid protein in living AD and MCI patients, and 11C-PIB PET imaging is a promising method to evaluate the prognosis of MCI.