磁共振弥散加权成像及表观弥散系数在儿童脑梗死中的诊断价值

目的探讨磁共振弥散加权成像（diffusionweightedmagneticresonanceimaging，DWI）及表观弥散系数（apparent diffusion coefficient，ADC）在脑梗死不同时期诊断及判断脑梗死转归中的价值。方法对26例患儿按发病就诊时间分为l期（0—72h）11例次，Ⅱ期（4-10d）12例次，Ⅲ期（10d以后）9例次，其中3例为复查，3例为复发脑梗死，共计29例次。对每例患儿进行MRI的T1加权像、配加权像、DWI序列扫描检查及ADC图像重建，于ADC图上取1个感兴趣区（regionsofinterest，ROI），计算出ROI的平均ADC值，同样的方法计算出镜像健侧相对应区的平均ADC值，并计算平均相对ADC值。结果DWI图像改变I期全部病例均呈现高信号；Ⅱ期11例次呈现高信号，1例次为低信号；Ⅲ期1例次为正常信号，1例次为高信号，2例次为混杂信号，1例次较前减低，其余均为低信号。在I期患儿ROI平均ADC值较对侧相应区域平均ADC值均下降，随着时间的发展Ⅱ期、Ⅲ期平均ADC值逐渐升高，梗死灶I期、Ⅱ期、Ⅲ期平均ADC值分别为0．434×10^-3mm2／s、0．653×10^-3mm2／s、1．600×10^-3mm2／s，对侧相应区域平均ADC值分别为0．938×10^-3mm2／s、0．814×10^-3mm2／s、0．757×10^-3mm2／s；Ⅰ期、Ⅱ期、Ⅲ期相对ADC平均值随着时间发展逐渐升高，分别为（51．5±16．8）％、（79．2±30．0）％、（210．9±45．1）％，差异均有统计学意义（P均〈0．05）。结论弥散加权MRI及ADC平均值对脑梗死早期诊断具有重要价值；脑梗死病灶ADC值和相对ADC值在时间上的变化规律为准确地判断脑梗死时期提供客观依据；弥散加权MRI及ADC平均值能为临床治疗及判断预后提供有效手段。

The diagnostic value of diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient values in children with cerebral infarction

Objective To explore the diffusion-weighted magnetic resonance imaging （DWI） and apparent dispersion coefficient（ADC） value in cerebral infarction diagnosis and judgment of cerebral infarc- tion outcome and staging of the value. Methods According to different stages,26 patients were divided into 3 phases, phase （6 -72 h） had 11 cases, phase 1I （4 - 10 d） had 12 cases, phase Ill （10 d later） had 9 ca- ses, of which 3 cases were reviewed,3 cases were recurrence of cerebral infarction. Each patient＇s MRI in- cluded T1 weighted imaging, T2 weighted imaging, DWI and ADC sequence scan image reconstruction, the ADC map obtained one regions of interest（ ROI）, and the mean ADC value of ROI were calculated, the aver- age ADC value of the corresponding contralateral area were also calculated by the same method, and then the mean relative ADC value were calculated. Results DWI image of all cases showed high signal, 11 cases showed high signal and 1 case showed low signal in phase Ⅱ. In phase Ⅲ,1 case showed normal signal and 1 case showed high signal,2 cases showed mixed signal,l case were reduced,and the rest were all low signal. Compared with the contralateral corresponding region, the average ADC values were reduced in phase Ⅰ The infarction average ADC values were 0. 434 ×10^-3mm2/s,0. 653 ×10^-3mm2/s, 1. 600×10^-3mm2/s in phase Ⅰ ,Ⅱ ,Ⅲ respectively, and the average ADC values of contralateral corresponding region were 0. 938 ×10^-3mm2/s,0. 814 ×10^-3mm2/s,0. 757 ×10^-3mm2/s respectively; the mean relative ADC values were （51.5 ± 16. 8 ） %, （79. 2± 30. 0 ） %, （ 210. 9 ± 45. 1 ） % in phase Ⅰ、Ⅱ、Ⅲ respectively （ P 〈 0. 05 ）. Conclusion ADC value of cerebral lesions area and relative ADC value of the variation in time provides an objective basis for the diagnosis of DWI, contributes to timely and accurately determine the age of cerebral lesions and pathophysiology of the changes.