鼻咽癌放疗后放射性脑病早期阶段磁共振成像及磁敏感加权成像表现及其临床意义

Evaluation of radiation-induced brain injury of early-stage nasopharyngeal carcinoma:magnetic resonance imaging and susceptibility weighted imaging compared

目的进一步了解鼻咽癌放射性脑病早期阶段患者脑常规磁共振成像(MRI)及磁敏感加权成像(SWI)表现,并初步探讨与其相关的病理机制。方法选择2010年7月至2012年12月,在浙江省肿瘤医院首次诊断为放射性脑病患者132例,分析首次确诊放射性脑病的常规MRI和SWI图像,评价病变发生部位、常规MRI和SWI图像特点。结果本组病例首程放疗后发生放射性脑病的中位时间为36个月,病灶均位于颞叶,以白质区为主,左侧48例,右侧36例,双侧48例。放射性脑病早期MRI可表现为:Ⅰ型(单纯水肿)58例,表现为均匀的颞叶白质水肿。Ⅱ型水肿(水肿伴微出血灶)74例,表现为信号不均匀的颞叶白质水肿,内见点状T2WI低信号影,SWI上点状低信号,且较T2WI所示范围更大。结论在鼻咽癌放射性脑病早期阶段病变主要发生于颞叶白质,可表现为单纯水肿或水肿伴微出血灶两种不同征象。放射性脑病早期阶段的MRI及SWI表现可能与微血管损伤的程度不同有关。

Objective To advance our understandings of the characteristics and pathologic mechanisms of mag- netic resonance imaging （MRI） and susceptibility weighted imaging （SWI） in patients with radiation encephalopathy who had early-stage nasopharyngeal carcinoma. Methods We recruited 132 patients who had received their initial diagnosis of radiation encephalopathy in Zhejiang Cancer Hospital between July 2010 and December 2012. This en- tailed analysis of the MRI and SWI features and the location involved. Results The median duration of initial radi- ation was 36 months, with all lesions located in the temporal lobe. There was a preponderance of white matter involve- ment （n=48 in the left cerebrum, n=36 in the right cerebrum and n=48 bilaterally involved）. The manifestations of ear- ly-stage radiation encephalopathy comprised simple cerebral edema, as evidenced by homogeneous edema on T2WI （type 1, n=58）, and cerebral edema with concomitant minute hemorrhagic foci, as evidenced by heterogeneous edema of the white matter with punctiform hypointensity signals on T2WI and extended punctiform hypointensity signals on SWI （type 2, n=74）. Conclusion The early-stage radiation encephalopathy is characterized by homogeneous edema or heterogeneous edema with minute cerebral hemorrhagic foci in the white matter of the temporal lobe, indicating the various degrees of capillary damage.