鼻咽癌放疗后放射性脑病的1H-MR波谱研究

目的　探讨鼻咽癌放疗后放射性脑病的磁共振氢波谱 (1H MRS)表现 ,了解N 乙酰天门冬氨酸 (NAA)、肌酸 (Cr)和胆碱 (Cho)这 3种物质的代谢规律 ,为放射性脑病的早期诊断提供方法。方法　对照组 10例健康志愿者 ,病例组 2 1例病理诊断为鼻咽癌并进行根治性放疗后经症状及影像学诊断为放射性脑病的病人 ,用化学位移成像法 (CSI)行1H MRS检查。观察各像素中NAA、Cr和Cho的含量、代谢图及它们之间比例。结果　放射性脑病MRI可见病灶中的液化坏死区 3种物质含量基本为零 ,代谢图中无信号 ;可见病灶中非液化坏死区NAA轻度升高 ,Cr和Cho明显降低或为零 ,NAA代谢图呈高信号 ,Cr和Cho低信号 ;可见病灶周边存在 1个区域性的NAA降低、Cr和Cho升高 ,NAA/Cr和NAA/Cho <1,代谢图中信号区分不明显 ;远离可见病灶的区域NAA、Cr和Cho含量及比例正常。结论　1H MRS发现物质代谢变化是有规律的 ,变化的区域大于MRI中可见病变区 ,为早期诊断提供了可能性。

An 1 H-MRS study on radioencephalopathy caused by radiotherapy of nasopharyngeal carcinoma

Objective To understand the rules of NAA,Cr,and Cho changes in 1H-MRS of radioencephalopathy (RE) caused by radiotherapy of nasopharyngeal carcinoma,and to offer the proof to make RE be detected as early as possible.Methods Chemical shift image 1H-MRS examinations were acquired from ten healthy volunteers (control group) and twenty-one cases (patient group) with nasopharyngeal carcinomas confirmed by pathology who were diagnosed as RE with nasopahryngeal carcinoma by symptoms and imaging diagnosis after radical radiotherapy.The integral of NAA,Cr,and Cho in pixels were observed,the metabolite maps were drawn,and the ratios of NAA/Cr and NAA/Cho were evaluated.Results The concentrations of NAA,Cr,and Cho were rarely observed in the necrosis and liquefaction,and there were no signals displayed in their metabolite maps.In the visible lesions,except necrosis and liquefactions,the integral of NAA increased slightly,whereas that of Cr or Cho decreased obviously or was zero.There was an area around the lesion where the integral of NAA decreased,whereas that of Cr or Cho increased.The signal in metabolite maps could not be distinguished.The ratios of NAA/Cr and NAA/Cho were less than 1.Further from the visible lesions,the integral of NAA,Cr,and Cho were normal,and the ratios of NAA/Cr and NAA/Cho were no less than 1.Conclusion There are rules of metabolite changes in RE.The area of abnormal metabolite found in RE with 1H-MRS is larger than in the visible lesion with MRI.This provides the possibility of earlier detection.