磁共振弥散张量成像在儿童偏瘫型脑瘫中的应用

目的探讨磁共振弥散张量成像（DTI）在儿童偏瘫型脑瘫中的应用价值。方法采集2o例偏瘫患儿及年龄相匹配的20例健康儿童的常规颅脑MRI及DTI数据，得到FA图、ADC图和VR图。测量锥体束经过的双侧内囊后肢、大脑脚和脑桥层面感兴趣区（ROI）的FA值、1-VR值和ADC值。数据分为三组，偏瘫组患侧（A组）、偏瘫组健侧（B组）和正常对照组左右侧平均值（c组）、采用配对样本t检验检测A-B组的差异，采用两独立样本t检验检测A-C组、13-C组差异。以内囊后肢及同例大脑脚为R0I，分别追踪锥体束。结果20例偏瘫组MRI平扫100％异常，表现为不同程度的脑室旁脑白质软化、脑萎缩、软化灶，脑白质减少、胼胝体发育不良和脑穿通畸形。所有偏瘫患儿彩色编码ADc图、FA图和VR图显示双侧大脑结构不对称，病变区域颜色混杂，边缘不清，其中16例DTT图显示病变倒不同程度锥体柬缺失。A组较B组、C组三个层面ROI的Fh值与1-VR值均显著减小，差异具有统计学意义（P〈0．05）；13组与C组间的FA值与1-VR值无显著差异。大脑脚层面ROI的ADc值B组较A组、c纽显著减小，差异具有统计学意义（P〈0．05），余组间ADC值差异无统计学意义；结论DTT能更直观显示白质纤维形态及走行，通过Fh值、1-VR值和ADc值等参数的测量进行量化分析，对偏瘫型脑瘫患儿运动功能障碍做出客观评价。

Application of MR Diffusion Tensor Imaging in Children with Hemiplegic Paralysis

Purpose To explore clinic application value of magnetic resonance Diffusion Tensor Imaging （DTI） in Children with hemiplegic paralysis. Material and method Conventional structure MRI data and DT1 data of 20 hemiplegic paralysis and 20 matched healthy controls were acquired, then fractional anisot- ropy （FA）, anisotropic volume ratio （VR） and apparent diffnsion coefficient （ADC） were computed. Regions of Interest （RO1） were setup along bilateral pyramidal tract on three levels （internal capsule, cerebral peduncle and Pons）. FA walue, 1-VR value and ADC value of each ROI were computed and recorded fin. group analysis. In order to do group analysis of CST parameter value, three groups were defined as followings： Group A was the affected side in hemiplegic paralysis; Group B was the healthy side in hemiplegic paralysis, Group C was the average value of bilateral CST in health controls. Matched sample T- test was employed to compare difference between Group A and B; independent sample T- test was adopted to detect difference of DTI parameters between Group A and C, Group B and C. 3 dimensions virtual fiber bundle of pyramidal tract were tracked by using Diffusion Tensor Tractography with setting Seed ROI on posterior limb of internal capsule and Target ROI on cerebral peduncle. Results MRI plan scan results showed 20 cases （100%） with positive findings in hemiplegic paralysis group. It included different degrees periventricular leukomalacia, cerebral atrophy, focus malacia, agenesis of corpus callosum and porencephalia. Color encoded ADC Map, FA Map and VR Map showed bilateral cerebral structure asymmetric, mixed color and blur edge. DTT map revealed lesions on the affected side pyrami- dal tract in paralysis group. Statistic analysis results of DTI： compared with Group B and C, FA value and 1-VR value in Group A on three level of CST showed statistically significant decreases （P〈0.05）; ADC Value only on cerebral peduncle level in Group B showed statistically significant decreases compared to Group A and C. Conclusion Color encoding map （FA map and VR map） and DTT map can directly show the alteration and lesion of the CST. DTI demon- strates great value in hemiplegic paralysis by measuring FA value, I-VR value, and ADC value of ROI along CST.