【摘要】 目的 探讨脑后部可逆性脑病综合征（posterior reversible encephalopathy syndrome，PRES）的临床及MRI表现，提高对PRES的认识。 方法 回顾性分析2007年1月-2010年12月期间5例PRES患者的MRI资料并进行追踪随访。5例PRES患者中男1例，女4例，肾性高血压及产后子痫各1例、妊娠高血压3例。5例均行MRI多序列平扫检查及弥散加权成像（diffusion weighted imaging，DWI），其中4例同时行磁共振血管造影（magnetic resonance angiography，MRA），2例行MRI增强检查。 结果 5例发病时均有高血压，以突发头痛、子痫或癫痫发作、意识障碍及视觉障碍为临床特点，及时正确治疗后症状于3~5 d左右消失，1例遗留肢体功能障碍。MRI显示5例多发病灶主要位于双侧顶枕叶皮质下白质内，额叶及颞叶后部各2例，两侧小脑及脑干1例，皮质受累2例，病变呈长T1、长T2信号、液体衰减反转恢复序列呈高信号，5例患者病灶DWI图呈高或等信号，表观弥散系数（apparent diffusion coefficient，ADC）图呈略高信号；1例顶叶及1例基底节区部分病灶DWI图呈高信号，ADC图呈低信号，提示弥散受限。2例增强无强化，脑膜呈线状强化。随访MRI显示3例病灶完全消失。1例左侧基底节区部分病灶发展为脑梗死。 结论 PRES是一种临床-影像综合征，正确认识这一综合征对其早期诊断和治疗具有非常重要的意义。MRI能够提供较为可靠明确的诊断，其扩散成像对判断PRES预后亦很有价值。【Abstract】 Objective To investigate the clinical features and MRI manifestations of patients with posterior reversible encephalopathy syndrome (PRES), in order to improve its recognition. Methods From January 2007 to December 2010, MRI data of 5 patients with PRES were retrospectively analyzed and the patients were followed up. Among them, one was male and four were female. There were one case of postpartum eclampsia, one of renal hypertention, and 3 of pregnancy-induced hypertension. All the five patients were examined by MRI diffusion weighted imaging (DWI), among whom four underwent additional magnetic resonance angiography (MRA) and one underwent enhanced MRI. Results All the five patients with PRES had hypertension and their clinical symptoms were characterized by sudden occurrence of headache, eclampsia or seizure of epilepsy, altered mental status, and visual disturbances. Clinical symptoms vanished about 3-5 days after prompt and appropriate treatment except one case of residual body function failure. MRI scanning demonstrated multifocal subcortical white lesions in bilateral parieto-occipital lobes in five patients, in bilateral frontal lobes in two patients, in bilateral post temporal lobes in two patients, in bilateral cerebellum in one patient, and in bilateral brainstem in one patient, and cortical involvement occurred in one patient. Lesions appeared as hyperintense signals on fluid attenuated inversion recovery (FLAIR) and T2-weighted images, hypointense signals on T1-weighted images, normal or increased intensity on DWI, and mild hypointensity on apparent diffusion coefficient (ADC) maps. Some lesions in parietal lobes or basal ganglia showed hyperintensity on DWI and isointensity on ADC maps. The lesions in two patients appeared unenhanced with gadolinium enhancement and the meninges assumed the linear strengthening. Follow-up MRI showed that foci in three patients vanished completely, and the focus in the left basal ganglia in one patient developed into cerebral infarction. Conclusions PRES is a clinical-neuroradiological transient condition. Correctly understanding this syndrome is meaningful for its early diagnosis. MRI can provide a more reliable diagnosis, and its proliferation image formation is also valuable in predicting the PERS prognosis.