两侧内囊非对称性的磁共振弥散张量成像研究

Asymmetry in internal capsule detected with magnetic diffusion tensor imaging

目的:利用弥散张量成像研究内囊后肢神经纤维存在的左右两侧非对称现象。方法:29名健康志愿者(其中右利手者20名,左利手者9名)纳入本研究。采用美国通用公司1.5T超导型磁共振机(GE Signa EXCITE),利用弥散张量成像技术分别测量左右两侧内囊后肢区域的表观弥散系数(ADC)、相对各向异性值(FA),以及弥散张量特征值λ1、λ2、λ3。应用配对t检验统计分析左右两侧数据的差异性。结果:右利手者大脑左右内囊后肢ADC和散张量特征值λ1无显著差异性;左侧FA(0.72±0.03)大于右侧FA(0.70±0.04),P=0.001;特征值λ2左侧(4.39±0.32)×10-3mm2/s小于右侧(4.50±0.33)×10-3mm2/s,P=0.016;特征值λ3左侧(2.19±0.34)×10-3mm2/s小于右侧(2.29±0.40)×10-3mm2/s,P=0.02。左利手者大脑左右内囊后肢各参数分析结果均无统计学意义。结论:右利手者大脑左侧内囊神经纤维受到了更佳的髓鞘保护。

Objective： To investigate the asymmetry of fibers in the posterior limb of the internal capsule with diffusion tensor imaging. Methods： Twenty-nine volunteers （right-handers：20,left-handers：9） were enrolled in this study. All the data were obtained using a 1.5 tesla scanner （Signa EXCITE Ⅱ. GE Medical Systems）. The parameters including apparent diffusion coefficient （ADC）,fractional anisotropy （FA） and eigenvalue λ1、λ2、λ3 were acquired from the posterior limb of the internal capsule in both hemisphere of brain,and paired t-test was used for statistical differences between the hemisphere. Results： No differences of ADC and λ1were found among the right-handers,but FA in the internal capsule of left hemisphere was larger than that in the right （0.72±0.03 vs 0.70±0.04,P=0.001）,and λ2,λ3 in the left was lower than that in the right [（4.39±0.32 vs 4.50±0.33）×10^-3 mm^2/s,P=0.016 and （2.19±0.34 vs 2.29±0.40）×10^-3 mm^2/s,P=0.024,respectively]. In contrast to the results among the right-handers,all parameters in the left-handers showed no statistical differences. Conclusion： The fibers in the posterior limb of the internal capsule of left hemisphere might be well sheathed with myelin among right-handers.