磁共振扩散张量成像评价小儿脑病的初步应用

目的应用扩散张量成像（DTI）来进一步评价小儿脑疾病，探讨DTI的诊断价值。方法对15例患各种脑病的小儿进行MRI检查，其中男性10例，女性5例，年龄为生后3天至11岁（平均年龄4．8岁）。采用Philips Intera Achieva 3．0 Tesla的超导MRI仪，用回波平面成像（EPI）的DTI技术，b为800s／mm^2，15个方向。观察彩色分数各向异性（FA）图和三维彩色编码图。结果15例患儿中，发育畸形2例，分别是胼胝体发育不良、巨脑回；脑室旁白质软化（PVL）7例；缺氧缺血性脑病3例；脑软化2例；脑积水1例。在巨脑回病例，常规MRI见右侧脑回发育不良，呈巨脑回畸形，右侧脑室扩大，在DTI上见右侧病变区白质束明显较对侧少。胼胝体发育不良病例在DTI张量图见胼胝体菲薄。在PVL和缺氧缺血性脑病病例均可见白质纤维束在放射冠颜色混杂，方向性混乱。脑软化病例可见白质纤维束部分中断。在脑积水病例可见白质束受压推移。结论DTI能够显示白质束的走向、绕行、交叉及推挤、中断等异常，可能对今后评估小儿脑病的预后转归有帮助。

Evaluation of infants and children brain encephalopathy by magnetism resonance diffusion tensor imaging: preliminary application

Objective To study the diagnostic value of magnetism resonance diffusion tensor imaging （DTI） in evaluating brain encephalopathy of infants and children. Methods The DTI was obtained in 15 cases with different encephalopathy of brain in infants and children from 3 days to 11 years. The MR imaging studies performed on Philips Intera Achieva 3.0 Tesla Superconductive MR scanner. The DTI was performed by a echo-planar spin-echo sequence with parameters of 5146/64/1 （TR/TE/excitations） ,and the motion probing gradients（MPG） were applied alone the 15 orthogonal directions. The resulting values for the gradient factor b were 800 s/mm^2. Their color tensor maps were generated and analyzed. Results Fifteen infants and children were enrolled in this study, among them there were developmental malformation 2 cases,including corpus callosum dysplasia and pachygyria,respectively, periventricular leukomalacia （PVL） 7 patients,hypoxic ischemic encephalopathy （HIE） 3 patients,encephalomalacia 2 cases and hydrocephalus one case. In the DTI,white matter tracts were reduced in the pachygyria and corpus callosum dysplasia. On PVL and/or HIE,anisotropy of white matter in the corona radiata were intermixed and directivity were disordered. White matter tracking broke on the lesion ofencephalomalacia,and the white matter tracts were pressed and passed in the hydrocephalus. Conclusion The DTI is able to display the white matter pathways and may reflect the direction of white matter tracts,as well as,including enwound,across,pressed and shifted of the tracts. Thus DTI may be helpful in predicting prognosis and outcome of encephalopathy.