^1H磁共振波谱在大鼠C6脑胶质瘤致痫性评估中的应用

^1H magnetic resonance spectroscopy in the evaluation of tumour associated epilepsy in C6 glioma rats

目的:1H磁共振波谱是研究活体脑组织及肿瘤组织代谢与生化指标测定的非侵袭技术,实验通过对种植C6脑胶质瘤大鼠的1H磁共振波谱在体观察,为非侵袭性评价肿瘤的致痫性提供帮助。方法:实验于2007-03/07在中国医科大学附属盛京医院中心实验室完成。①分组处理:选用雌性近交系Wistar大鼠共40只,随机分为实验组和对照组两组各20只。实验组制作C6脑胶质瘤移植动物模型,根据皮质脑电图记录结果确定癫痫发作,并将其分为致痫组与非致痫组;对照组在相同部位注射等量Ham'sF-12培养液。②观察指标:所有大鼠取出内置皮质电极后行1H磁共振波谱检查。分别选择肿瘤周围区及肿瘤实质区作为感兴趣区对每一体积元进行化学位移成像。所测定的主要代谢产物包括N-乙酰基天门冬氨酸、肌酸、胆碱、乳酸/脂质、谷氨酸及γ-氨基丁酸。以肌酸为参照波峰,分别计算各代谢产物与肌酸波的积分面积进行比较。结果:32只大鼠纳入结果分析。①实验组大鼠C6脑胶质瘤肿瘤实质区及肿瘤周围区胆碱及脂质波峰高于对照组(P<0.01,0.05);而肿瘤实质区N-乙酰基天门冬氨酸及谷氨酸波峰高于对照组(P<0.05)。②C6脑胶质瘤致痫组肿瘤周围区谷氨酸波峰高于非致痫组(P<0.01);而γ-氨基丁酸波峰低于非致痫组(P<0.01)。同时,肿瘤周围区乳酸/肌酸两组间比较差异也具有统计学意义(P<0.05)。结论:①1H磁共振波谱检查可为脑胶质瘤的恶性程度及其侵袭性的活体判定提供依据。②通过活体监测肿瘤周围皮质谷氨酸与γ-氨基丁酸二者含量的变化,也可为非侵袭性评价肿瘤的致痫性提供帮助。

AIM： ^1H magnetic resonance spectroscopy （^1H MRS） tissue metabolism and biochemical index determination is noninvasive technique for in vivo cerebral tissues and tumor We performed ^1HMRS in 16 cases of implanted C6 rat gliomas to evaluate tumour associated epilepsy noninvasively. METHODS： The experiments were performed in Central Laboratory of Shengjing Hospital of China Medical University from March to July 2007. ①Totally 40 female inbred line Wistar rats were used for this study, and were randomized into experimental group and control group with 20 in each group. C6 glial tumors were implanted in 20 rats of the experimental group. They were divided into epileptic group and non-epileptic group according to the recorded findings of cortical electroencephalogram. Twenty rats of the control group received Ham＇s F12 medium without tumor cells in the same location. ②After removal of intracranial electrocorticalgram, every rat was treated with ^1HMRS examination, and every volume element in both tumor region and peritumoral region was selected as region of interest to perform the chemical-shift MR imaging. Relative metabolite levels including N-acetylaspartate, creatine, choline, lactate/lipid, glutamate and γ-aminobutyric acid were measured. Creatine was related to the peak area, and integral area between each products and creatine was compared. RESULTS： Thirty-two of 40 rats were involved in the result analysis. ①Compared to the control group, both choline and lip levels in both tumor regions and peritumoral regions of C6 gliomas were prominently elevated （P 〈 0.01,0.05）, while both N-acetylaspartate and glutamate levels were elevated in tumor regions of C6 gliomas （P 〈 0.05）. ②Glutamate level was higher in tumor regions in the epileptic group than the non-epileptic group （P 〈 0.01 ）, while γ-aminobutyric acid level was lower than the non-epileptic group （P 〈 0.01）. There were statistical differences in lactic acid-to-creatine ratios in tumor regions between epileptic group and non-epileptic group （P 〈 0.05）. CONCLUSION： ^1HMRS plays an important role not only in determination of malignancy and invasiveness of cerebral gliomas, but also in noninvasive evaluation of tumor associated epilepsy through monitoring alteration of glutamate/γ-aminobutyric acid levels in peritumoural cortex in vivo.