脑淀粉样血管病与阿尔茨海默病18F-FDG PET/CT代谢改变图型对比研究

  目的  比较脑淀粉样血管病(cerebral amyloid angiopathy，CAA)与阿尔茨海默病(Alzheimer's disease，AD)患者的脑代谢差异，评价¹⁸F-脱氧葡萄糖(fluorodeoxy glucose，FDG)正电子发射断层显像/计算机体层成像(positron emission tomography/computed tomography, PET/CT)脑显像对CAA和AD的鉴别价值。  方法  回顾性纳入2020年12月至2021年6月北京协和医院符合修订Boston标准的很可能CAA患者以及年龄与其相近的AD患者。随机纳入同期行¹⁸F-FDG PET/CT检查且认知功能正常的人群为对照。对3组¹⁸F-FDG PET/CT图像进行视觉分析和定量分析。  结果  共入选符合纳入和排除标准的10例很可能CAA患者(CAA组)、10例AD患者(AD组)以及11例认知功能正常的对照人群(对照组)。视觉分析结果显示，相较对照组，AD组典型表现为双侧基本对称的颞顶叶代谢减低，以颞叶内侧、后扣带回代谢减低最为显著；CAA组皮层代谢减低区呈无特定规律分布，代谢减低或缺损区与出血区域相关。基于体素的脑代谢图像定量分析结果显示，相较对照组，AD组后扣带回、海马旁回、顶叶、颞叶内侧的代谢显著减低(P < 0.01)；CAA组广泛白质区以及尾状核头、胼胝体、前扣带回、颞叶外侧皮层等处代谢显著减低(P < 0.01)。基于脑区的定量分析显示，CAA组枕叶/后扣带回(occipital/posterior cingulate, O/PC)相对脑桥的¹⁸F-FDG标准摄取值比值(standardized uptake value ratio，SUVr)明显低于AD组(0.91±0.05比1.07±0.08，P < 0.001)；O/PC SUVr鉴别很可能CAA、AD的曲线下面积为0.98(95%CI:0.93~1.00)，最佳临界值为0.96，灵敏度为100%，特异度为90%。  结论  CAA与AD患者的¹⁸F-FDG PET/CT显像呈明显不同的代谢降低图型；O/PC SUVr或可作为二者鉴别诊断的敏感指标。

Comparative Study of 18F-FDG PET/CT Metabolic Alteration Patterns in Cerebral Amyloid Angiopathy and Alzheimer's Disease

  Objective  To compare the metabolism pattern of the brain in patients with cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD), and to evaluate the value of brain imaging of 18F-fluorodeoxy glucose (FDG) positron emission tomography/computed tomography (PET/CT) in differentiating CAA and AD.  Methods  We retrospectively recruited patients with probable CAA (revised Boston diagnostic criteria) and AD of similar age from December 2020 to June 2021 at Peking Union Medical College Hospital. Patients with normal cognition that underwent 18F-FDG PET/CT during the same period were randomly included as controls. We performed visual analysis and quantitative analysis of PET/CT imaging in the three groups.  Results  Ten patients with probable CAA (CAA group), 10 patients with AD (AD group), and 11 control subjects with normal cognitive function (control group) that met the inclusion and exclusion criteria were enrolled. Visual analysis showed that, compared with the control group, the AD group showed mostly bilateral symmetrical hypometabolism in temporoparietal lobes, with the most significant hypometabolism in the medial temporal lobe and posterior cingulate gyrus; the CAA group exhibited unspecific cortical hypometabolic areas corresponding to hemorrhage. Quantitative analysis of voxel-based brain metabolism images showed that metabolism in the posterior cingulate gyrus, parahippocampal gyrus, parietal lobe, and medial temporal lobe was significantly reduced in the AD group compared with the control group (P < 0.01); metabolism was significantly reduced in the extensive white matter areas, as well as in the caudate nucleus head, corpus callosum, anterior cingulate gyrus, and lateral temporal cortex in the CAA group (P < 0.01). Quantitative analysis based on brain regions showed that the standardized uptake value ratio (SUVr) of 18F-FDG in the occipital/posterior cingulate (O/PC) was significantly lower in the CAA group than in the AD group (0.91±0.05 vs. 1.07±0.08, P < 0.001); the area under the curve for O/PC SUVr identification of probable CAA and AD was 0.98 (95% CI: 0.93-1.00), with an optimal threshold of 0.96, exhibiting sensitivity of 100% and specificity of 90%.  Conclusions  Probable CAA and AD patients exhibited distinct brain hypometabolism patterns. O/PC SUVr can be a sensitive indicator for differential diagnosis between CAA and AD.