大鼠全脑照射后早期放射性脑损伤的磁共振波谱与病理对照研究

Experimental Correlative Study on MRS Findings and Their Pathologic Basis of Early Changes Brain Lesions after Whole Brain Irradiation in Rats

目的探讨磁共振波谱(MRS)揭示放射性脑损伤的细胞代谢改变及病理早期动态演变价值。材料与方法将成年SD大鼠25只随机分为对照组、10Gy、20Gy、30Gy单次照射组和30Gy分次(每周1次,每次10Gy)照射组,用6MeV电子线作垂直全脑照射,各组大鼠于照射后1个月均行MRI及1HMRS检查,分析NAA、Cho和Cr等信号强度改变,以积分面积进行比较,计算NAA/Cr、Cho/Cr和NAA/Cho。各组大鼠在行1HMRS检查后,立即断头处死取大脑后分两侧大脑半球,一侧大脑半球行常规病理HE染色检查,另一侧行电子显微镜检查。结果所有被检查大鼠的大脑MRI均未见异常表现;各照射组大鼠大脑的NAA/Cr、Cho/Cr和NAA/Cr值与对照组相比均有统计学差异。结论用1HMRS来监测大鼠全脑照射后脑组织内的NAA、Cho和Cr的浓度变化,在形态学发生改变之前就可检测出脑组织的代谢异常,并能反映大鼠全脑照射后早期脑组织内超微结构改变,且对放射性脑损伤的病情发展作出准确的估测。

Objective To discuss the value of magnetic resonance spectroscopy （MRS） changes in radiation cerebrum damage compared with early pathological results. Materials and Methods 25 maturity SD rats were randomly divided into 5 groups, including control, 10Gy, 20Gy, 30Gy once irradiation group and 30Gy group （10Gy/l times per week weeks group）, whole cerebrum irradiation with 6MeV electric rays. These groups were performed with MRI and tH MRS after 1 month to analyze concentration changes of NAA,Cho and Cr, compare with integra-area to calculate NAA/Cr,Cho/Cr and NAA/Cho. Cerebral hemisphere was taken respectively, one side examined with HE Staining and the other side with electron micrograph. Results All cerebrums in MRI without abnormality signal were seen in all cerebrums on MRI, there were marked statistical difference between NAA/Cr, Cho/Cr and NAA./Cr of all irradiation groups and control group. Conclusion We can detect metabolism abnomality of cerebrum constitution before morphology changes appeared and show earlier ultrastructure changes of cerebrum constitution after irradiation by concentration monitoring to NAA, Cho and Cr.