回波平面成像序列用于儿童中枢神经系统定量磁化率成像

Echo planner imaging sequence for quantitative susceptibility mapping of central nervous system in children

目的分析回波平面成像(EPI)序列在儿童中枢神经系统定量磁化率成像(QSM)中的应用价值。方法回顾性分析43例接受常规头部MR检查儿童,分别以传统梯度回波序列及EPI序列采集中枢神经系统QSM,获得传统标准QSM(Std-QSM)及EPI-QSM定量图;测量全脑及19个脑区QSM定量值,对比以2种方法所获结果的差异,分析其相关性。结果Std-QSM采集时间4 min 53 s,EPI-QSM为24 s。以2种方法所获左侧苍白球、左侧尾状核、双侧壳核、双侧额中回及左侧颞中回的QSM定量值差异均有统计学意义(P均<0.05),其余脑区QSM定量值差异均无统计学意义(P均>0.05)。以2种方法所测各脑区QSM定量值均呈正相关(r/r_(s):0.519~0.919,P均<0.001)。以Std-QSM与EPI-QSM所测全脑QSM定量值分别为0.388(-0.303,1.416)、0.452(-0.171,1.465),差异无统计学意义(Z=-0.488,P=0.625),且二者呈线性正相关(R=0.766,P<0.001),回归方程为SStd-QSM=1.35×S_(EPI-QSM)-0.25。结论以EPI序列采集儿童中枢神经系统QSM可明显缩短采集时间。

Objective To analyze the value of echo planar imaging(EPI)sequence for quantitative susceptibility mapping(QSM)of central nervous system in children.Methods Data of 43 children who underwent routine head MR examination were enrolled.QSM of central nervous system was acquired sing traditional gradient echo sequence and EPI sequence,respectively,the traditional standard QSM(Std-QSM)and EPI-QSM quantitative map were obtained,and QSM quantitative values of the whole brain and 19 brain regions were measured and compared,while the correlations of measuring results using different methods were analyzed.Results The acquisition time of Std-QSM was 4 min 53 s,while of EPI-QSM was reduced to 24 s.Quantitative QSM values of left ventral pallidum,left caudate nucleus,bilateral putamen,bilateral middle frontal gyrus and left middle temporal gyrus obtained with two methods were significantly different(all P<0.05),while no significant difference of quantitative QSM values of the other brain regions was found(all P>0.05).There were positive correlations of quantitative QSM values of brain regions measured with different methods(r/r_(s):0.519—0.919,all P<0.001).The quantitative QSM value of the whole brain measured with Std-QSM and EPI-QSM was 0.388(-0.303,1.416)and 0.452(-0.171,1.465),respectively,without significant difference(Z=-0.488,P=0.625).There were linear positive correlations of QSM quantitative values of the whole brain measured with Std-QSM and EPI-QSM(R=0.766,P<0.001),and the regression equation was S Std-QSM=1.35×S_(EPI-QSM)-0.25.Conclusion EPI sequence could be used to acquire central nervous system QSM in children,which might significantly shorten the scanning time.