多个静息态功能磁共振成像指标检测儿童失神性癫痫脑活动的比较研究

A comparative study of multiple resting state functional magnetic resonance imaging indices to detect epileptic activity in childhood absence epilepsy

目的全面评估常见静息态功能磁共振成像(rs-fMRI)指标检测儿童失神性癫痫(CAE)异常脑活动的能力。方法回顾性收集自2010年2月至2021年9月于南京大学医学院附属金陵医院就诊的20例CAE患儿的同步采集脑电图-功能磁共振成像(fMRI)数据,排除2例头动较大的CAE患儿后,共18例患儿的44段发放状态fMRI数据用于后续研究,使用广义线性模型计算获得了癫痫放电相关的激活图。同时纳入94名年龄和性别相匹配的健康对照,采集其rs-fMRI数据。基于fMRI数据集,计算12种常见rs-fMRI指标[低频振幅(ALFF)、分数低频振幅(fALFF)、局部一致性(ReHo)、功能连接密度(FCD)、长程FCD、短程FCD、流入格兰杰因果关系密度(GCD-in)、流出GCD(GCD-out)、净流入GCD(GCD-int)、rs-fMRI滞后分析(RSLA)、Hurst指数及大脑熵值],并采用两样本t检验,比较并获取了患儿组与健康对照组之间的差异脑图,采用戴斯系数评价各指标与激活图的重合度。结果CAE患儿癫痫放电相关的血氧水平依赖正激活主要在双侧丘脑,负激活主要在默认模式网络(DMN)相关脑区。各种静息态指标检测到的异常脑区之间存在明显的重叠:与健康对照组相比,CAE患儿静息态指标ALFF、fALFF、ReHo、Hurst指数、GCD-in、GCD-out及短程FCD在双侧丘脑升高,而FCD、长程FCD、GCD-int及RSLA降低;与健康对照组相比,CAE患儿ALFF、fALFF、ReHo、短程FCD、GCD-out、RSLA及大脑熵值在DMN降低,而FCD、长程FCD、GCD-in及GCD-int升高。FCD系列指标与全面棘慢波放电相关的血氧水平依赖激活脑图的戴斯系数最高(长程FCD的戴斯系数为0.365,FCD则为0.362),而Hurst指数表现最低(戴斯系数为0.142)。结论多个rs-fMRI指标不同程度地反映了CAE患儿异常脑活动变化,其中FCD分析对CAE患儿的癫痫活动有较好的检测能力。rs-fMRI技术有助于理解CAE的病理生理机制,寻找可靠的影像学标志物。

Objective To comprehensively evaluate the ability of common resting state functional magnetic resonance imaging(rs-fMRI)indices to detect abnormal brain activity in childhood absence epilepsy(CAE).Methods Simultaneous electroencephalography-functional magnetic resonance imaging(fMRI)data of 20 patients with CAE who were treated in the Jinling Hospital,Nanjing University School of Medicine from February 2010 to September 2021 were retrospectively collected.After excluding 2 patients with CAE with greater head movement,44 fMRI data containing discharges from 18 patients were obtained finally.The generalized spike and slow-wave discharges(GSWD)related fMRI activation mappings were obtained by using the generalized linear model.At the same time,94 age-and sex-matched healthy controls underwent rs-fMRI scanning.Meanwhile,12 indices of rs-fMRI were calculated respectively[amplitude of low frequency fluctuation(ALFF),fractional amplitude of low frequency fluctuation(fALFF),regional homogeneity(ReHo),functional connectivity density(FCD),long FCD,local FCD,granger causality density(GCD)-in,GCD-out,GCD-int,resting state functional magnetic resonance imaging lag analysis(RSLA),Hurst index and brain entropy].Two-sample t-tests were employed to detect significant differences in 12 indices of rs-fMRI.The Dice coefficient was used to evaluate the overlap between different brain maps of 12 indices of rs-fMRI and the GSWD-related blood oxygenation level dependent(BOLD)activation.Results Positive activation of GSWD-related BOLD in CAE was mainly in the bilateral thalamus,and negative activation was mainly in default mode network(DMN)related brain regions.There was a significant overlap between the abnormal brain regions detected by various resting-state indicators:compared with normal controls,ALFF,fALFF,ReHo,GCD-in,GCD-out and local FCD were elevated in the bilateral thalamus,while FCD,long FCD,GCD-int and RSLA were decreased in CAE;ALFF,fALFF,ReHo,local FCD,GCD-out,RSLA and brain entropy were decreased in the DMN,while FCD,long FCD,GCD-in and GCD-int were increased in CAE.The Dice coefficient of long FCD was the highest(0.365),FCD was 0.362,while the Hurst index showed the lowest(0.142).Conclusions Rs-fMRI indices variously revealed abnormal brain activity in CAE,in which the FCD is better for detection of epileptic activity.Rs-fMRI could be helpful to understand the pathophysiological mechanism of CAE,and to find reliable imaging markers.