鼻咽癌放射治疗后脑干放射性损伤的MRI征象分析

目的：分析鼻咽癌放疗后脑干放射性损伤的MRI表现，探讨其影像学特征性改变。方法：分析11例鼻咽癌放疗诊断为放射性脑干损伤的病人MRI表现和临床资料及随诊观察。结果：脑干放射性损伤的主要临床表现为相应节段颅神经受损及对侧肢体感觉障碍，无力或瘫焕，MRI显示脑干病变可累及脑桥（9例），脑桥＋中脑（1例）及中脑＋延髓上升（1例），表现为局限性脑水肿并局灶性坏死；病灶为斑片状或不规则形，T1WT呈低信号或等信号，T2WI呈高信号或等高混杂信号，T1WI＋Gd_DTPA增强扫描可见斑片状，类圆形或不规则环状强化，周围轻度水肿，无占位效应，7例经治疗后行MRI复查，1例症状改善，MRI异常信号消失。5例病灶无变化，其中2例症状有改善，3例症状体征无变化，1例症病灶增大，结论：NPC放射治疗后脑干放射性损伤的MRI表现具有一定特征。

Sign Analysis of MRI Findings of Radiation Encephalopathy of Brain Stem after Radiotherapy for Nasopharyngeal Cancer

Objective: To study MRI findings and clinical manifestations of radiation encephalopathy of brain stem after nasopharyngeal carcinoma and to evaluate their charateristic imageological changes. Method: To analyse MRI findings, clinical and follow-up observation in 11 patients with radiation encephalopathy of brain stem of nasopharyngeal cancer. Results: The main clinical manifestations of radiation encephalopathy of brain stem were relevant segment injuries of cranial nerve and heterolateral hemidysesthesia, weakness or semisideration. MRI manifestations of brain stem involved pons (9 cases), pons+mesencephalon (1 case) and mesencephalon+upper segment of medullary bulb (1 case). MRI features: limited brain edema and focal cerebral necrosis. The lesions were spotty or irregular. T 1WI showed that there was low signal intensity or isosignalintensity. T 2WI showed high signal intensity or mixed hyper- and iso-intensity. T 1WI plus Gd-DTPA enhancement showed spotty circular-like or irregular rings of enhancement. Some had no intensification . There was light edema round it, no space occupying effect. 7 cases in MRI follow-up examinations: the symptom of one case has improved. Its MRI abnormal signal disappeared. The foci of 5 cases has no changes. The symptoms of 2 cases have improved and the symptoms and physical signs of 3 cases have no changes among them. The focus of 1 case has enlarged. Conclusion: The MRI findings have some characteristics in radiation-induced of brain stem after NPC radiation encephalopathy.