脑淀粉样血管病

1、脑淀粉样血管病(Cerebral amyloid angiopathy,CAA)CT-MRI病例图片影像诊断分析临床病史】：患者，女性，76岁，既往有进行性的痴呆病史，出现了意识丧失、括约肌张力丧失以及右侧面部下垂。76-year-old female patient with a history of progressive dementia, who presented with loss of consciousness, loss of sphincter tone, and right sided facial droop.5JS影像园XCTMR.com【影像图片】CT-MRI图像5

2、JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com【影像表现】：MRI of the brain without contrast shows diffuse cortical atrophy as well as multiple small (< 5 mm) cortical-subcortical foci of decreased signal intensity, best seen in GRE sequences (green arrows Figure 1 and Figur

3、e 2). Some of these focal areas of low signal intensity are not seen or are barely discernible on T2-weighted sequences (yellow arrows Figure 3 and Figure 4 ), and not seen at all on T1-weighted (Figure 5 and Figure 6) or FLAIR sequences (Figure 7 Figure 8). No areas of abnormal signal intensity are

4、 seen in the basal ganglia. In addition, areas of increased white matter signal intensity, compatible with leukoencephalopathy, are best seen on FLAIR sequences (blue arrows in Figure 7 and Figure 8 ).颅脑MR平扫显示弥漫性的皮质萎缩和多发性小点状（5mm）皮质-皮质下的局灶性低信号影，在GRE序列上显示的最清楚（图1,2）。这些局灶性的低信号影在T2序列上很难显示清楚（图3、4），在所有的T1序

5、列和Flair序列上基本上不能显示出来（图5、6、7、8）。基底节区未见异常信号，另外白质信号强度的增高，符合脑白质病，在Flair序列上显示的更清楚（图7、8）5JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com5JS影像园XCTMR.com【影像诊断】：Cerebral amyloid angiopathy (CAA) 脑淀粉样血管病5JS影像园XCTMR.com【诊断要点】：Cerebral amyloid angiopathy is an important cause of spontaneous intracran

6、ial hemorrhage in a cortical, subcortical, and leptomeningeal location in the elderly normotensive individual. 对于正常血压的老年患者，在皮层、皮层下、软脑膜出现自发性的脑出血，脑淀粉样血管病是一种重要的病因5JS影像园XCTMR.com    T2*-weighted GRE imaging is currently the modality of choice for detecting microhemorrhages associated with

7、 CAA, which appear as focal areas of signal loss due to magnetic field inhomogeneities caused by hemosiderin deposits.T2*序列是检测CAA相关的微出血首选序列，由于含铁血黄素的沉积导致磁场不均匀而表现为局限性的信号丢失。 【讨论】：Cerebral amyloid angiopathy (CAA) is a significant cause of cortical-subcortical cerebral bleeds in the normotensive elderly

8、 individual. In CAA, beta-amyloid protein is deposited in the media and adventitia of small to medium sized blood vessels in a cortical, subcortical, and leptomeningeal distribution. These deposits are associated with fibrinoid necrosis, vessel wall fragmentation, and microaneurysms, all of which pr

9、oduce vascular fragility and lead to spontaneous micro and/or macrohemorrhages, with the latter sometimes having devastating consequences. Fibrinoid necrosis can also lead to blood vessel narrowing and subsequent distal ischemia. CAA is sometimes called Congophilic amyloid angiopathy, because beta-a

10、myloid deposits are highlighted with Congo red stain and show yellow-green birefringence under polarized light.5JS影像园XCTMR.com    脑淀粉样血管病是正常血压的老年患者出现皮层及皮层下脑出血的一个重要原因。在CAA，淀粉样蛋白沉积于皮层、皮层下和软脑膜内的小到中等大小的血管的中间层和外膜。这些沉积物常常和纤维蛋白样坏死、血管壁碎片破裂以及微动脉瘤相关，所有的这些引起血管壁变脆并导致自发性的微出血或大出血，后者可能会引起破坏性的后果，纤维蛋白

11、样坏死同时也可以导致血管壁的狭窄和继发的远端缺血，CAA某些时候也被称为Congophilic淀粉样血管病，因为淀粉样蛋白沉积物用刚果红染色是高亮的，并且在偏振光下显示黄-绿双折射。5JS影像园XCTMR.com5JS影像园XCTMR.com    CAA has been found at autopsy in up to one third of individuals between 60 and 70 years old, and in up to two thirds 90 years and older. Nevertheless, the major

12、ity of patients with CAA remain asymptomatic, and thus the condition is currently under recognized. When symptoms do arise, they are similar to those of a transient ischemic attack or dementia, which are nonspecific findings making CAA difficult to diagnose clinically. Patient symptomatology is usua

13、lly related to macrohemorrhages, defined as larger then 5mm, and can resemble an acute ICH. CAA is not associated with systemic amyloidosis, yet is strongly associated with Alzheimer disease.5JS影像园XCTMR.com    60-70岁的个头尸检CAA的发现率大于1/3，90岁以上上升至2/3以上，然而大部分的CAA患者都没有症状。当症状出现的时候，它们也类似于短暂性的脑

14、缺血发作或痴呆，这些改变是非特异性的，导致CAA很难被临床诊断。病人的症状通常与大出血（大于5mm）相关， 并且可以类似于急性的颅内出血。CAA并不与系统性的淀粉样变相关，而与阿尔茨海默病强烈相关。5JS影像园XCTMR.com    Radiographic findings of CAA normally include cortical and subcortical hemorrhages, atrophy, and leukoencephalopathy. Microhemorrhages associated with CAA are normally

15、 not seen on CT, T1-weighted, or T2-weighted sequences. Therefore, if CAA is suspected clinically, or in the event that cortical-subcortical focal intracranial hemorrhages are seen on a noncontrast enhanced CT, an MRI should be obtained, which includes T2*-weighted gradient-echo (GRE) sequences. At

16、present, GRE is one of the most sensitive sequences for the detection of acute and chronic hemorrhages, like the ones associated with CAA. The hemosiderin present within these cerebral hemorrhages, causes local magnetic field inhomogeneities, with a prominent loss of signal on T2*-weighted GRE seque

17、nces. Susceptibility-weighted imaging (SWI) is another sequence that is gaining acceptance, which is also very sensitive in detecting cerebral microhemorrhages. Nevertheless, for a definitive diagnosis of CAA, biopsy or autopsy is required. It is important to note that patients taking anticoagulants

18、 or aspirin which are diagnosed with CAA, should be counseled regarding the risks and benefits of treatment. Finally, no treatment is currently available to halt or reverse beta-amyloid protein deposition associated with CAA.5JS影像园XCTMR.com    CAA的放射学改变通常包括皮质和皮质下出血，脑萎缩，和脑白质病。CAA的微出血在CT、T1序列或T2序列上通常不能发现。因此