【摘要】 目的 探討腦后部可逆性腦病綜合征（posterior reversible encephalopathy syndrome，PRES）的臨床及MRI表現，提高對PRES的認識。 方法 回顧性分析2007年1月-2010年12月期間5例PRES患者的MRI資料并進行追蹤隨訪。5例PRES患者中男1例，女4例，腎性高血壓及產后子癇各1例、妊娠高血壓3例。5例均行MRI多序列平掃檢查及彌散加權成像（diffusion weighted imaging，DWI），其中4例同時行磁共振血管造影（magnetic resonance angiography，MRA），2例行MRI增強檢查。 結果 5例發病時均有高血壓，以突發頭痛、子癇或癲癇發作、意識障礙及視覺障礙為臨床特點，及時正確治療后癥狀于3~5 d左右消失，1例遺留肢體功能障礙。MRI顯示5例多發病灶主要位于雙側頂枕葉皮質下白質內，額葉及顳葉后部各2例，兩側小腦及腦干1例，皮質受累2例，病變呈長T1、長T2信號、液體衰減反轉恢復序列呈高信號，5例患者病灶DWI圖呈高或等信號，表觀彌散系數（apparent diffusion coefficient，ADC）圖呈略高信號；1例頂葉及1例基底節區部分病灶DWI圖呈高信號，ADC圖呈低信號，提示彌散受限。2例增強無強化，腦膜呈線狀強化。隨訪MRI顯示3例病灶完全消失。1例左側基底節區部分病灶發展為腦梗死。 結論 PRES是一種臨床-影像綜合征，正確認識這一綜合征對其早期診斷和治療具有非常重要的意義。MRI能夠提供較為可靠明確的診斷，其擴散成像對判斷PRES預后亦很有價值。【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.