真实头模型中改良电休克与磁休克治疗的电场仿真分析

Electric field simulation and analysis of modified electroconvulsive therapy and magnetic seizure therapy in a realistic human head model

改良电休克和磁休克均是重度抑郁症的有效治疗方法,改良电休克治疗疗效较好但会使患者产生认知和记忆障碍的副作用,而磁休克治疗几乎不会产生副作用,但疗效相比于改良电休克较弱。为研究造成这两种不同结果的原因,本文对比了改良电休克和磁休克治疗方法在真实大脑中产生的电场强度及其空间分布的差异,并通过有限元方法对由磁共振成像得到的真实头模型进行改良电休克和磁休克治疗的电场强度仿真计算。改良电休克治疗仿真的电极位置使用双边刺激的标准位置,磁休克治疗仿真的线圈形状为圆形线圈。使用电场强度与神经激活阈值的比值分布评估大脑中的刺激强度及刺激的聚焦性。结果显示,改良电休克治疗在脑区中产生的刺激强度比磁休克治疗更强,且激活脑区范围更广;其在灰质区域的刺激强度是磁休克治疗的17.817倍,在白质区域的刺激强度是磁休克治疗的23.312倍,在海马组织中产生的刺激强度是磁休克治疗的35.162倍。改良电休克治疗激活了超过99.999%的脑区,然而磁休克治疗只激活了0.700%的脑区。因此,与磁休克治疗相比,在脑区中产生的刺激强度更强、激活脑区范围更广可能是改良电休克治疗疗效更好的原因。另一方面,改良电休克治疗在海马组织中产生的高强度刺激可能是造成认知和记忆障碍副作用的原因。基于本文研究结果,期待未来可以研究更精确的临床量化治疗方案。

Modified electroconvulsive therapy（MECT） and magnetic seizure therapy（MST） are effective treatments for severe major depression. MECT has better efficacy in the treatment than MST, but it has cognitive and memorial side effects while MST does not. To study the causes of these different outcomes, this study contrasted the electric filed strength and spatial distribution induced by MECT and MST in a realistic human head model. Electric field strength induced by MECT and MST are simulated by the finite element method, which was based on a realistic human head model obtained by magnetic resonance imaging. The electrode configuration of MECT is standard bifrontal stimulation configuration, and the coil configuration of MST is circular. Maps of the ratio of the electric field strength to neural activation threshold are obtained to evaluate the stimulation strength and stimulation focality in brain regions. The stimulation strength induced by MECT is stronger than MST, and the activated region is wider. MECT stimulation strength in gray matter is 17.817 times of that by MST, and MECT stimulation strength in white matter is 23.312 times of that by MST. As well, MECT stimulation strength in hippocampi is 35.162 times of that by MST. More than 99.999% of the brain volume is stimulated at suprathreshold by MECT. However, MST activated only 0.700% of the brain volume.The stimulation strength induced by MECT is stronger than MST, and the activated region is wider may be the reason that MECT has better effectiveness. Nevertheless, the stronger stimulation strength in hippocampi induced by MECT may be the reason that MECT is more likely to give rise to side effects. Based on the results of this study, it is expected that a more accurate clinical quantitative treatment scheme should be studied in the future.