电刺激健康成人小腿前外侧皮肤腰髓功能磁共振成像特征研究

目的通过基于快速自旋回波的功能磁共振序列，检测电刺激健康成人小腿前外侧皮肤时引起腰髓内神经元活动的激活特征；同时，对比横轴位与矢状位的激活信号特征，验证功能磁共振成像技术在腰髓方面研究的可行性及重复性。 方法使用GE 1.5T Signa MR扫描仪及八通道标准脊髓(CTL)线圈用于发射和接受射频(RF)脉冲。12名健康志愿者，男性、女性各6名，年龄23～27岁，平均(25.00±1.13)岁。使用电针刺激仪，以断续脉冲(20Hz)，刺激右侧小腿前外侧区皮肤，采用组块设计方法，即R₁-S₁-R₂-S₂-R₃-S₃-R₄。利用单次激发快速自旋回波序列分别采集横轴位与矢状位的功能磁共振图像。使用SPM8软件获得静息态和刺激态图像差异间的t检验图，阈值P＝0.01，设置激活聚类数为0。对矢状位不同脊椎节段内激活像素数及信号强度变化百分比改变使用非参数K相关样本分析法进行统计分析，用非参数Wilcoxon配对检验对矢状位-轴位上分别获取的数据进行统计学分析。 结果除2名志愿者因运动幅度过大被排除外，余下10名志愿者相应脊髓节段内均检测到激活信号。矢状位上，激活信号主要位于T₁₂(10/10)椎体水平，且信号强度变化百分比主要集中于0.0%～2.0%，T₁₁(2/10)、L₁(3/10)椎体水平亦检测到少许激活信号。横轴位上，激活信号主要位于刺激同侧脊髓灰质背侧区(7/10)，对侧脊髓灰质背侧区(5/10)及双侧脊髓灰质腹侧区(3/10)也可观察到少许激活。T₁₂椎体水平，横轴位与矢状位的平均激活像素数间比较(Z＝－1.825，P>0.05)及横轴位与矢状位的平均信号强度变化百分比间比较(Z＝－1.376，P>0.05)均差异无统计学意义。 结论利用1.5T超导MR研究腰髓功能磁共振成像是可行的，且激活信号存在一定的特征，主要位于T₁₂椎体水平，并具有一定的重复性；不同方位腰髓功能磁共振成像结果具有一致性。

The characteristics of fMRI for lumbar spinal cord by electrically stimulating anterolateral legskin in healthy adults

ObjectiveTo detect the characteristics of fMRI for lumbar spinal cord by stimulating anterolateral legs based on a fast spin echo sequence, and compare the differences of the activation signal between transverse and sagittal plane to determine the feasibility and repeatability of the functional magnetic resonance imaging (fMRI) for lumbar spinal cord. MethodsGE1.5T Signa MR syetem was employed to transmit and receive RF pulse by using an eight-channel CTL coil.Twelve volunteers were stimulated by an electrical stimulator (intermittent pulse, frequency 20 HZ) on the anterolateral leg skin to detect fMRI activation signal.Spinal fMRI was acquired by a single-shot fast spin echo (SSFSE) sequence based on signal enhancement by the extra vascular water proton (SEEP) effect.Scanning parameters were as follows (sag/axial): TR=6 000 ms, TE=6.8/6.6 ms, thickness=4/7 mm, space=0.5 mm, FOV=24 cm×24 cm, parent=256×256, NEX=1, and ETL=64.Block design was used as the activation pattern, such as R₁-S₁-R₂-S₂-R₃-S₃-R₄.The imaging data were analyzed with SPM8 and Marsbar. ResultsActivation signal of the lumbar spinal cord was found in all volunteers except for the data of two volunteers were taking off for their movements out of range.Time-intensity changes curves were correlated with periods of rest and active in both axial and sagittal views through the spinal cord.In the sagittal view, the activation was mainly located at the T₁₂(10/10), and the signal intensity percentage varied from 0.0% to 2.0%.Few signal was also found at T₁₁(2/10) and L₁(3/10). In the axial view, the activation signal mainly focus on the ipsilateral dorsal horn (7/10), and few signal was also found at the contra-lateral dorsal horn (5/10) and bilateral ventral horn (3/10). At T₁₂ vertebral level, there was no statistically significant difference in the average activation signal pixels and signal intensity changes between sagittl and transverse plane(Z=-1.825, Z=-1.376; P>0.05). ConclusionsThere are feasibilites of fMRI of lumbar spinal cord based on SEEP effect using 1.5T MR scanner, and the characterized activation signal was focused on the T₁₂ with a high repeatability.Moreover, activation signal of axial lumber is consistent with that of sagittal lumber.