可逆性后部脑病综合征影像学特征及诊断

可逆性后部脑病综合征是一种临床放射学综合征,临床主要表现为头痛、意识障碍、视力改变和癫痫等,影像学改变主要为累及双侧后脑部（顶枕叶）皮质下白质的可逆性改变。部分病例可能会有皮质受累,T2加权像及液体衰减反转恢复序列（FLAIR）像呈高信号,弥散加权成像DWI呈低信号或等信号改变。表观弥散系数（ADC）增高提示血管源性脑水肿。高ADC值治疗后可逆性好。低ADC值则为不可逆损伤或者是真正的梗死。病理改变大部分认为与血压自我调节功能失调及内皮细胞破坏有关。自从该综合征首次被描述以来,许多病例报告显示多种疾病会引起此类综合征,包括高血压、子痫、应用细胞毒性及免疫抑制剂等,合理的诊断及治疗能够使症状及影像学改变迅速恢复,如果诊断不当,则可能会引起不可逆的细胞性脑水肿。

Neuroimaging and dignosis of posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome （PRES） is a clinicoradiologic syndrome characterized clinically by headaches, altered consciousness, visual disturbances and seizures and radiological changes predominate in the posterior white matte which can be resolved. And cortex can be involved. MR imaging demonstrates hyperintensity on T2 weighted image and fluid attenuated inversion recovery sequence （FLAIR）. These areas may appear hyperintense, hypointense, or isointense on diffusion-weighted imaging （DWI） with increased apparent diffusion coefficient （ADC） values. Lesions with high ADC values are most often reversible, whereas those with decreased ADC values usually progress to true infarction. The pathophysiology of PRES is thought to be related to disordered cerebral autoregulation and endothelial damage. This syndrome has been subsequently described in many medical conditions, including hy- pertensive encephalopathy, eelampsia, and the use of cytotoxie and immunosuppressive drugs since its first description. The clinical and radiologic abnormalities are reversible when diagnosed and treated properly, when unrecognized, con- version to irreversible cvtotoxic edema mav occur.