磁共振技术在非典型弥漫性轴索损伤诊断中的价值

Imaging study on diagnostic value of MR techniques in non-typical diffuse axonal injury

目的探讨磁共振技术液体衰减反转恢复序列(fluid attenuated inversion recovery,FLAIR)和氢质子MR波谱(1H-MR spectroscopy,1H MRS)在非典型弥漫性轴索损伤(diffuse axonal injury,DAI)临床诊断中的价值。方法选择2002年10月至2008年1月收治的符合本研究纳入标准的颅脑外伤患者58例,根据诊断标准将全部病例分为DAI组和非典型DAI组,进行FLAIR和1HMRS检查,再随机选择20名健康成年人作为对照组。观察FLAIR对DAI组及非典型DAI组病例的诊断能力;利用1HMRS比较DAI组和非典型DAI组胼胝体膝部、压部和基底节N-乙酰天门冬氨酸/肌酸和磷酸肌酸(NAA/Cr)、胆碱复合物/肌酸和磷酸肌酸(Cho/Cr)、肌醇/肌酸和磷酸肌酸(mINs/Cr)以及谷氨酸和谷氨酰胺/肌酸和磷酸肌酸(Glx/Cr)等指标的差异。结果较之常规MRI,FLAIR对轴索病灶的发现能力明显提高,非典型DAI组的病灶分布及形态和DAI组类似,两者不同在于非典型DAI组分布于间脑以下水平的病灶明显少于DAI组。DAI组、非典型DAI组和对照组的NAA/Cr与Cho/Cr在胼胝体膝部、压部和基底节部位差异均有统计学意义,mINs/Cr和Glx/Cr在胼胝体膝部和压部差异有统计学意义;和对照组及非典型DAI组相比,DAI组于胼胝体膝部、压部和基底节有NAA/Cr降低和Cho/Cr升高,于胼胝体膝部和压部有mINs/Cr和Glx/Cr升高;和对照组相比,非典型DAI组于胼胝体膝部和压部有NAA/Cr降低和Cho/Cr升高,于胼胝体膝部有mINs/Cr升高,但变化程度均比DAI组低。结论非典型DAI组不仅有和DAI组类似的病灶分布和形态,还在胼胝体部位有与DAI组类似的伤后生化代谢改变,区别在于损伤波及范围和严重程度的不同。表明DAI不仅是重型脑伤的一种,它也存在于轻、中型脑伤中,磁共振技术在非典型DAI诊断中有很大价值。

Objective To investigate the value of MR techniques,FLAIR（fluid attenuated inversion recovery） and 1 HMRS（proton magnetic resonance spectroscopy） in the diagnosis of non typical diffiuse axonal injury （DAD. Meibods A prospective imaging study was performed in 58 patients with craniocerebral injury admitted from October 2002 to January 2008. Fifty-eight patients were divided into DAI group （33 cases） and non typical DAI group （25 cases） according to respective criterions. Twenty healthy adults served as control group. The diagnostic value of FLAIR was evaluated compared with traditional MRI; then the ratio of NAA/Cr,Cho/Cr,mINs/Cr,and Glx/Cr at basal ganglia and genu and splenium of corpus callosum were quantified using I HMRS and compared among the groups. Results Compared with traditional MRI,the diagnostic capacity of FLAIR to axonal injury was greatly improved,and the characters of lesion＇s size,shape and distributing of non-typical DAI group were similar to those of DAI group. The difference between the two groups lied in the extension that DAI group had obviously more lesions located in brain stem and cerebellum. The results of NAA/Cr and Cho/Cr among three groups at genu and splenium of corpus callosum and basal ganglia were all statistically significant,and those of mINs/Cr and Glx/Cr at genu and splenium of corpus callosum were both statistically significant. Compared with control group and non-typical DAI group,at those three checkpoints DAI group demonstrated decreased NAA/Cr and increased Cho/Cr,at genu and splenium of corpus callosum DAI group also showed increased mINs/Cr and increased Glx/Cr. Non typical DAI group displayed same result of NAA/Cr and Cho/Cr at genu and splenium of corpus callosum,and same result of mlNs/Cr at genu of corpus callosum, but all these indices of non typical DAI group had lower change degree compared with DAI group. Conclusion Compared with DAI group,non-typical DAI group has not only similar lesion characters on FLAIR, but also similar neurochemical and molecular changes at corpus callosum post-injury detected by 1HMRS. Thus it is concluded that DAI lies not only in severe traumatic brain injury,but in moderate and even light ones, and MR techniques have potential value in the diagnosis of non-typical DAI.