磁共振弥散张量成像在脑室旁白质软化症中的应用

Diffusion tensor MR imaging in assessment of periventricular leukomalacia

目的通过对12例脑室旁白质软化症(PVL)患儿的磁共振弥散张量成像(DTI)及白质纤维素成像(FT)研究,评价DTI及FT在缺氧缺血性脑损伤后脑内主要白质纤维束变化方面的应用价值。方法选取12例临床确诊为脑瘫的PVL患儿,同时选择无窒息史的健康儿童志愿者12例进行对照研究。对这两组儿童进行MRI及DTI检查(扩散敏感梯度方向15个)。根据矢量元素和部分各向异性值(FA值)生成彩色弥散张量图(DTI图),通过DTI图选取所有可识别白质纤维束的中心部分作为感兴趣区(ROI),计算患儿与对照组各主要白质纤维束的FA值,进行配对t检验。结果试验组和对照组的ICAL、脑干CST、ML、MCP以及外囊(EC)白质纤维束示踪图像肉眼未见直观差异,而患儿组ICPL、AF、PTR、CR、CG、SLF以及胼胝体压部的白质纤维较对照组明显变细。所有12名患儿的ICPL、AF、PTR、CR、CG、SLF、SCC以及GCC的FA值较健康对照组同侧对应位置FA值显著减低(P<0.05),而患儿与对照组的ICAL、ML、MCP以及脑干CST的FA值配对t检验未见显著差异(P>0.05)。结论DTI及FT在评价缺氧缺血性脑损伤后脑内主要白质纤维束变化方面有较高的应用价值。

Objective To investigate MR diffusion tensor imaging （DTI） and fiber tractography （FT） in the assessment of altered major white mater （WM） fiber tracts in periventricular leukomalacia （PVL）. Methods Twelve children suffered from PVL and 12 age-matched normal controls with normal MRI findings and no neurological abnormalities were recruited. DTI was performed with 15 different diffusion gradient directions and DTI color maps were created from fractional anisotropy （FA） values and the three vector elements, FA values on diffusion tensor color maps were compared between the patients and the controls. Quantitative analysis was performed using regions of interest （ROI） method settled on the central part of all identifiable WM fibers. All the FA values of these WM fibers were analyzed by paired t test. Results Visual investigation of WM fiber tracts showed that ICAL, brainstem CST, ML, MCP, and external capsule （EC） was similar in controls and subjects. However, ICPL, AF, PTR, CR, CG, SLF and corpus callosum, were all attenuated in size. All 12 cases of PVL showed a significant mean FA reduction in ICPL, AF, PTR, CR, CG, SLF, SCC, and GCC in comparison to the ipsilateral regions of healthy controls （P〈0.05）. However, there were no statistically significant differences of ICAL, ML, MCP, and brainstem CST when analyzed with a two-tailed Student t test for paired data （P〉0. 05）. Conclusion DTI can provide more information for understanding the pathophysiology of motor disability and associated sensory handicap in PVL.