弥漫性轴索损伤磁敏感加权成像的实验研究

Experimental Study of Susceptibility Weighted Imaging in Diagnosis of Diffuse Axonal Injury

目的:用磁敏感加权成像(SWI)观察大鼠弥漫性轴索损伤(DAI)后的变化规律。方法:采用液压颅脑损伤模型制备32只DAI的SD大鼠模型,并于模型制作前、DAI后6h和24h分别进行常规磁共振成像和SWI成像(GE 3.0T超导磁共振成像仪)。比较各序列图像上DAI病灶检出数,在各时间点SWI图像上测量双侧皮髓质交界处感兴趣区(ROI)的相位弧度值,并分析其变化规律。结果:SWI对DAI病灶的检出率显著高于常规的MRI序列(P<0.05)。伤后6h,骨窗侧出血灶相位弧度值较致伤前变为负值;对侧相位值升高,差异有统计学意义(P<0.05),伤后24h,DAI鼠出血灶部位的相位弧度值较伤后6h相位弧度值变化差异无统计学意义(P>0.05);结论:磁敏感加权成像(SWI)检出弥漫性轴索损伤病灶的敏感性高于常规MRI序列,相位弧度值的变化反映了DAI的宏观变化过程,其变化规律与顺磁性物质有关。

Purpose：To observe the changes of susceptibility weighted imaging（SWI） in rats with diffuse axonal injury（DAI）.Methods： Models of DAI were established in 32 SD rats by fluid percussion injury method. MRI examinations were performed on 6h and 24 h after injury. The findings of MRI were analyzed. Regions of interest（ROI） were placed at the junction of the bilateral cortex and medulla of parietal lobe, on which the changes of the phase value at different time were observed, and the number of DAI lesions between different sequences were compared. Results： The radian values of hemorrhage regions were negative in DAI rats, there were significant differences of the radian value between injured side and contrast side（P〈0.05）; The radian values of DAI rats which had a bone window were increased and then decreased on 6h and 24 h after injury. Six hours after injury, the radian values were decreased in each DAI group, and there were significant differences in DAI group between that before and after injury（P〈0.05）; the number of hemorrhage lesions detected on SWI was the highest than that on other sequences（P〉0.05）. Conclusion： The sensitivity of SWI for detection of DAI is significantly higher than that of other sequences. The changes of radian value can reflect the macroscopic progress, the variation is in accordance with the existance of paramagnetic substances.