老年人放射性脑损伤的动态磁共振波谱研究

目的 探讨老年人放射性脑损伤的代谢特点.方法 对15例接受放射治疗(放疗)老年鼻咽癌患者(老年组)在治疗前和接受放射线剂量为20 Gy、40 Gy、60 Gy时分别进行磁共振波谱检查,观察不同剂量时双侧颞叶主要代谢物比值的变化趋势;选择23例同期接受放疗的青年鼻咽癌患者为对照组.结果 放疗前,老年组N-乙酰天门冬氨酸(NAA)与肌酐(Cr)的比值(NAA/Cr)为1.86±0.17,胆碱(Cho)与Cr的比值(Cho/Cr)为1.84±0.23,分别高于和低于对照组(2.15±0.22、1.62±0.31,P＞0.05);放疗过程中,两组均表现为NAA峰和Cho峰降低,放射线剂量达20 Gy前NAA/Cr、Cho/Cr和NAA和Cho比值(NAA/Cho)降幅较小,放射线剂量20～60 Gy阶段降幅加快;放疗结束时,老年组Cho/Cr降低幅度小于对照组(P＜0.05),NAA/Cr降低的幅度大于对照组,差异有统计学意义(P＜0.01).结论 接受边缘放射线辐射条件下,老年人放射性脑损伤发生较早,神经元损伤程度大于青年人,而对胶质细胞损伤程度相对较小.

Abstract：

Objective To study the metabolic characteristics of temporal lobe injury during the radiotherapy in the elderly with nasopharyngeal carcinoma through 1H- magnetic resonance spectroscopy (MRS). Methods The 15 aged and 23 young cases among 80 cases with nasopharyngeal carcinoma confirmed clinically and receiving radiotherapy for the first time were involved in the same period of July 2006 to May 2009. Conventional MRI scanning and bilateral temporal MRS were performed before and during radiotherapy at radiation dosages of 20 Gy, 40 Gy, and 60 Gy respectively. The spectroscopy morphology and the ratios of the three main metabolites were compared and analyzed. Results The values of N-acetylasparate (NAA)/creatine (Cr) was lower and choline-containing compound (Cho)/Cr ratio was higher in aged group than in young group before radiotherapy (P＞0.05). The spectroscopy morphology stepped down, NAA, Cho, NAA/Cr, Cho/Cr and NAA/Cho decreased to some extent along with the adding of radiation dosages in the course of radiotherapy. At the end of radiotherapy, the decreased amplitude of NAA/Cr value was larger in aged group than in control group (P＜0.01), and the amplitude of Cho/Cr value was lower than other group. Conclusions The neurons of aged patients with nasopharyngeal carcinoma have a weak tolerance to the radiation, brain injury occurs earlier and heavier in aged patients than in young patients. It is necessary to prevent neuron injury early.

Dynamic magnetic resonance spectroscopy study on radiation-induced temporal lobe injury in the elderly during radiotherapy

Objective To study the metabolic characteristics of temporal lobe injury during the radiotherapy in the elderly with nasopharyngeal carcinoma through 1H- magnetic resonance spectroscopy (MRS). Methods The 15 aged and 23 young cases among 80 cases with nasopharyngeal carcinoma confirmed clinically and receiving radiotherapy for the first time were involved in the same period of July 2006 to May 2009. Conventional MRI scanning and bilateral temporal MRS were performed before and during radiotherapy at radiation dosages of 20 Gy, 40 Gy, and 60 Gy respectively. The spectroscopy morphology and the ratios of the three main metabolites were compared and analyzed. Results The values of N-acetylasparate (NAA)/creatine (Cr) was lower and choline-containing compound (Cho)/Cr ratio was higher in aged group than in young group before radiotherapy (P＞0.05). The spectroscopy morphology stepped down, NAA, Cho, NAA/Cr, Cho/Cr and NAA/Cho decreased to some extent along with the adding of radiation dosages in the course of radiotherapy. At the end of radiotherapy, the decreased amplitude of NAA/Cr value was larger in aged group than in control group (P＜0.01), and the amplitude of Cho/Cr value was lower than other group. Conclusions The neurons of aged patients with nasopharyngeal carcinoma have a weak tolerance to the radiation, brain injury occurs earlier and heavier in aged patients than in young patients. It is necessary to prevent neuron injury early.