Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada.
Ann Neurol. 2009 Dec;66(6):825-32. doi: 10.1002/ana.21796.
Case series with (11)C-PK11195 and positron emission tomography (PET) in stroke patients suggest that activated microglia may be detected in remote brain regions with fiber tract connections to the lesion site as an indicator of poststroke neuroinflammation. However, the specificity of these imaging findings remains to be demonstrated.
In a prospective controlled study, we measured microglia activity using (11)C-PK11195-PET along the pyramidal tract, as defined by diffusion tensor imaging, in 21 patients with first-time acute subcortical ischemia within 2 weeks of stroke. Uptake ratios (affected vs unaffected side) were determined for a set of standardized volumes of interest along the pyramidal tracts (PT). Uptake ratios from patients in whom the PT was affected were compared with those in whom the PT was not affected. Uptake ratios were related to motor deficit and lesion size according to correlation analyses.
Increased uptake ratios were only found in patients in whom the PT was affected by stroke. In the affected hemisphere, uptake was increased at the level of pons, midbrain, and internal capsule, but not in the oval center. The extent of remote microglia activation was independent of infarct size or clinical measures of stroke severity.
A specific activation of microglia was only found in patients in whom the PT was affected by the stroke and only caudal (anterograde) to the lesion; no activation was found in the retrograde direction or in those patients in whom the PT was not affected. These findings were independent of infarct size and may represent changes secondary to early Wallerian degeneration.
对脑卒中患者进行的（11）C-PK11195 病例系列研究和正电子发射断层扫描（PET）研究表明，在与病变部位有纤维束连接的远程脑区可能会检测到激活的小胶质细胞，作为脑卒中后神经炎症的指标。然而，这些影像学发现的特异性仍有待证明。
在一项前瞻性对照研究中，我们在 21 例脑卒中后 2 周内首次出现急性皮质下缺血的患者中，使用（11）C-PK11195-PET 沿弥散张量成像定义的锥体束测量小胶质细胞活性。通过受影响和未受影响侧的摄取比（affected vs unaffected side）来确定锥体束（PT）的一组标准化感兴趣区的摄取比。受脑卒中影响的患者的摄取比值与不受影响的患者的摄取比值进行比较。根据相关分析，将摄取比值与运动缺陷和病变大小相关联。
仅在 PT 受脑卒中影响的患者中发现了摄取比值增加。在受影响的半球，在脑桥、中脑和内囊水平上摄取增加，但在卵圆中心没有增加。远程小胶质细胞激活的程度与梗死灶大小或脑卒中严重程度的临床指标无关。
仅在 PT 受脑卒中影响且仅在病变部位顺行（anterograde）的患者中发现了特定的小胶质细胞激活，在逆行方向或未受影响的患者中没有发现激活。这些发现与梗死灶大小无关，可能代表早期 Wallerian 变性的继发变化。
