腦淀粉樣血管病

1、腦淀粉樣血管病(Cerebral amyloid angiopathy,CAA)CT-MRI病例圖片影像診斷分析臨床病史】：患者，女性，76歲，既往有進(jìn)行性的癡呆病史，出現(xiàn)了意識喪失、括約肌張力喪失以及右側(cè)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影像園XCTMR.com【影像圖片】CT-MRI圖像5

2、JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com【影像表現(xiàn)】：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 ).顱腦MR平掃顯示彌漫性的皮質(zhì)萎縮和多發(fā)性小點狀（5mm）皮質(zhì)-皮質(zhì)下的局灶性低信號影，在GRE序列上顯示的最清楚（圖1,2）。這些局灶性的低信號影在T2序列上很難顯示清楚（圖3、4），在所有的T1序

5、列和Flair序列上基本上不能顯示出來（圖5、6、7、8）?；坠?jié)區(qū)未見異常信號，另外白質(zhì)信號強(qiáng)度的增高，符合腦白質(zhì)病，在Flair序列上顯示的更清楚（圖7、8）5JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com5JS影像園XCTMR.com【影像診斷】：Cerebral amyloid angiopathy (CAA) 腦淀粉樣血管病5JS影像園XCTMR.com【診斷要點】：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. 對于正常血壓的老年患者，在皮層、皮層下、軟腦膜出現(xiàn)自發(fā)性的腦出血，腦淀粉樣血管病是一種重要的病因5JS影像園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*序列是檢測CAA相關(guān)的微出血首選序列，由于含鐵血黃素的沉積導(dǎo)致磁場不均勻而表現(xiàn)為局限性的信號丟失。 【討論】：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影像園XCTMR.com    腦淀粉樣血管病是正常血壓的老年患者出現(xiàn)皮層及皮層下腦出血的一個重要原因。在CAA，淀粉樣蛋白沉積于皮層、皮層下和軟腦膜內(nèi)的小到中等大小的血管的中間層和外膜。這些沉積物常常和纖維蛋白樣壞死、血管壁碎片破裂以及微動脈瘤相關(guān)，所有的這些引起血管壁變脆并導(dǎo)致自發(fā)性的微出血或大出血，后者可能會引起破壞性的后果，纖維蛋白

11、樣壞死同時也可以導(dǎo)致血管壁的狹窄和繼發(fā)的遠(yuǎn)端缺血，CAA某些時候也被稱為Congophilic淀粉樣血管病，因為淀粉樣蛋白沉積物用剛果紅染色是高亮的，并且在偏振光下顯示黃-綠雙折射。5JS影像園XCTMR.com5JS影像園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影像園XCTMR.com    60-70歲的個頭尸檢CAA的發(fā)現(xiàn)率大于1/3，90歲以上上升至2/3以上，然而大部分的CAA患者都沒有癥狀。當(dāng)癥狀出現(xiàn)的時候，它們也類似于短暫性的腦

14、缺血發(fā)作或癡呆，這些改變是非特異性的，導(dǎo)致CAA很難被臨床診斷。病人的癥狀通常與大出血（大于5mm）相關(guān)， 并且可以類似于急性的顱內(nèi)出血。CAA并不與系統(tǒng)性的淀粉樣變相關(guān)，而與阿爾茨海默病強(qiáng)烈相關(guān)。5JS影像園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影像園XCTMR.com    CAA的放射學(xué)改變通常包括皮質(zhì)和皮質(zhì)下出血，腦萎縮，和腦白質(zhì)病。CAA的微出血在CT、T1序列或T2序列上通常不能發(fā)現(xiàn)。因此