多序列MRI评估脑外伤微出血及弥漫性轴索损伤

Evaluation of traumatic cerebral microbleeds and diffuse axonal injury by using multiple MRI sequences

目的探讨MR常规序列(T1WI、T2WI、T2FLAIR)、扩散加权成像(diffusion-weighted imaging, DWI)及磁敏感序列(susceptibility weighted imaging, SWI)在脑外伤微出血及弥漫性轴索损伤(DAI)中的应用价值。方法对48例脑外伤患者,应用3.0T MR行常规MRI、DWI及SWI序列成像,比较各序列微出血灶及DAI病灶的检出率差异,并分析病灶在这些序列上的位置分布特点、信号特征。结果联合多种序列共检出547个剪切灶及微出血灶。T1WI检出205个病灶,T2WI检出358个病灶,T2FLAIR检出432个病灶,DWI检出396个病灶,SWI检出471个病灶,SWI病灶检出率高于常规T1WI(χ^2=273.94)、T2WI(χ^2=63.59)、T2FLAIR(χ^2=9.648)、DWI序列(χ^2=31.27),其检出率差异具有统计学意义(P<0.01)。DWI检出的大部分(80%)非出血性剪切灶表现为扩散受限、ADC值减低。SWI图像上微出血灶表现为条状、点状及类圆形低信号,病灶主要分布在皮髓质交界区及深部脑白质区域,位于皮髓交界区病灶排列呈甩鞭样或串珠状,具有特征性。结论 SWI序列对脑外伤微出血的敏感性高,多种序列联合应用对脑外伤微出血和DAI各期的诊断有重要的临床价值。

Objective To investigate the value of T1WI, T2WI, T2FLAIR, diffusion-weighted imaging(DWI) and susceptibility weighted imaging(SWI) in the traumatic cerebral microbleeds and diffuse axonal injury(DAI) in the brain. Methods 48 patients with traumatic brain Injury were subjected to conventional MRI sequences(T1WI, T2WI, T2FLAIR), DWI, SWI at 3.0 T MR. The differences in the detection rates of micro-hemorrhages and DAI lesions were compared, and the location distribution characteristics and signal characteristics of the lesions were analyzed. Results A total of 547 lesions were counted by the combined use of all sequences. 205 lesions were detected in the T1WI sequence, 358 lesions were detected in the T2WI sequence, 432 lesions were detected in the T2FLAIR sequence, 396 lesions were detected in the DWI sequence, and 471 hemorrhagic lesions was detected in the SWI sequence. The detection rate of DAI lesions were higher on SWI when compared with that of T1WI(χ^2=273.94), T2 WI(χ^2=63.59), T2FLAIR(χ^2=9.648), DWI(χ^2=31.27), and the difference in detection rate was statistical significance(P<0.01). The most of non-hemorrhagic shearing lesions(80%) detected on DWI showed limitation of diffusion and decrease of ADC value. The DAI lesions were hypointensity and strip, dot and round-like on the SWI images, which were located in the deep white matter or the corticomedullary junction of the frontal and temporal lobes, and multiple lesions were arranged bead or whip like which were characteristic features. Conclusion It may be a extremely sensitive technology to detect hemorrhagic shearing lesions on SWI. The combined application of various magnetic resonance sequences in diagnosis of DAI has important clinical value.