鼻咽癌放疗后迟发性放射性脑损伤的MRI特征

目的 探讨鼻咽癌放疗后迟发性放射性脑损伤的MRI特征.资料与方法 回顾性分析57例鼻咽癌放射治疗后10个月～20年发生的迟发性放射性脑损伤患者的MRI、表观扩散系数(ADC)、磁共振波谱学(MRS)表现.结果 病变主要位于颞叶,颞叶病灶范围较大时累及额叶或小脑,少部分病灶位于脑干,其MRI示坏死脑组织的T_1、T_2弛豫时间延长,呈不均匀信号改变,并脑水肿.增强扫描坏死区呈散在斑点状、小结节状强化,或皱缩状、"花边"状强化团块;ADC为稍高信号;MRS表现为胆碱(Cho)峰升高、N-乙酰天门冬氨酸(NAA)峰降低.其中,54例发生于颞叶,2例合并额叶损伤,1例合并小脑损伤,3例发生于脑干;颞叶病变累及双侧38例,单侧16例.结论 MRI可以清晰显示鼻咽癌放疗后放射性脑损伤的范围,ADC及MRS具有一定特征性,有益于鉴别诊断.鼻咽部随访复查应仔细观察双侧颞叶及脑干情况.

Imaging Characteristics of MRI in Delayed Radiation-induced Brain Injury after Nasopharyngeal Carcinoma Radiotherapy

Objective To discuss the characteristics of MRI in delayed radiation-induced brain injury after nasopharyngeal carcinoma radiotherapy. Materials and Methods The characteristics of MRI, ADC, MRS were reviewed in 57 patients with delayed radiation-induced brain injury after nasopharyngeal carcinoma radiotherapy of 10-moth to 20-year. Resuits Most of the delayed radiation-induced brain injury lesions occurred in the temporal lobes,and a small number of lesions located in the brain stem. The frontal lobe or cerebellar were involved when the temporal lesions were large. MRI demonstrated prolonged T_1 and T_2 relaxation time of the necrosis of the brain tissue, they might showed heterogeneous signal intensity and cerebral edema. MR enhanced T, WI showed the lesions presented punctate,nodular enhancement or shrinksshaped flower-laced enhancement. The ADC map showed higher signal. Cho peak was higher and NAA peak lower in ~1HMRS. The lesions of 54 patients occured in the temporal lobe,and 2 with frontal lobe involved, 1 with cerebellar involved. The lesions of 3 patients oocured in brain stem. The lesions of 38 patients occurred in bilateral temporal lobes, including lesions of 2 patients directly affects the frontal lobe, 16 patients occurred in unilateral temporal lobe. Conclusion MRI can clearly demonstrate the radiation-induced brain injury, and ADC and MRS are benefit in the differential diagnosis.