弥散张量成像与血氧水平依赖功能磁共振成像在脑肿瘤诊断中的联合应用

Combined DTI and BOLD-fMRI in evaluation of brain tumors involving the motor system

目的弥散张量成像(diffusion tensor imaging,DTI)与功能磁共振成像(functional magnetic resonance imaging,fMRI)对脑肿瘤术前评估具有重要意义。文中探讨DTI与血氧水平依赖功能磁共振成像(blood oxygen level dependent-fMRI,BOLD-fMRI)对累及运动通路的脑肿瘤诊断中联合应用的价值。方法对16例累及皮层运动区及锥体束的脑肿瘤患者行fMRI及DTI检查,另以10例健康者作为对照,2例患者术后复查。fMRI采用双侧交替进行的大拇指对掌运动作为任务刺激。所有数据进行离线后处理,fMRI图像观察运动皮层区激活情况,DTI处理后得到FA图及DEC图,测量患侧与健侧锥体束的FA值,并行纤维束成像,用fMRI Merge 1.2软件将fMRI与DTT图像叠加。结果每例患者的健、患侧主运动区(primarymotor area,M1)、辅助运动区(supplementary motor area,SMA)均激活,其中12例患侧M1区信号低于健侧,3例患侧M1区信号高于健侧,1例健侧与患侧M1区信号无明显差别,11例患侧M1区信号移位,8例患者患侧SMA区及健侧M1区的激活程度比健康人增强。DTI显示患侧锥体束FA值下降,白质纤维束与脑肿瘤的关系可分为单纯移位、移位伴破坏和单纯破坏3种类型。fMRI与DTT联合应用可显示肿瘤、皮层运动区及皮层下白质纤维束之间的关系。锥体束的保留、移位与M1区的激活、移位具有一致性。结论联合应用fMRI与DTI可显示肿瘤、皮层运动功能区及白质纤维束之间的关系,有助于邻近的脑运动功能区肿瘤患者术前评估。

Objective Diffusion tensor imaging（DTI） and functional magnetic resonance imaging（fMRI） play an important role in preoperative comprehensive evaluation of brain tumors adjacent to the motion function area.This study aimed to investigate the value of combined DTI and blood oxygen level dependent-fMRI（BOLD-fMRI） in the diagnosis of brain tumors involving the motor system.Methods We performed fMRI and DTI for 16 patients with brain tumors involving the cortical or subcortical motor pathway,10 normal subjects and 2 postoperative patients by the fist clenching paradigm.The fMRI analysis was conducted for imaging processing,FA and DEC maps obtained,fractional anisotropy（FA） measured at the affected and contralesional sides,tractography of the pyramidal tracts employed,and the fMRI results overlaid into DTT using the fMRI Merge 1.2 Software.Results The primary motor area（M1） and supplementary motor area（SMA） were activated for every patient.The M1 signal at the injured side was lower than that at the uninjured side in 12 of the patients,higher in 3,not significantly different from the latter in 1,and its position changed in 11.Compared with the healthy volunteers,the signal intensity of SMA at the injured side and that of M1 at the uninjured side were obviously reinforced in 8 cases.The FA value was significantly reduced at the affected than at the contralesional side of the pyramidal tract.The relationship between the tracts and tumors fell into 3 types： simple displacement,displacement with disruption,and simple disruption.In almost all the patients,the anatomical relationship among the lesions,functional activation maps and related white matter fiber tracts were clearly revealed.The reservation and displacement of pyramidal tracts were consistent with the activation and displacement of M1.Conclusion The combined use of DTI and fMRI helps identify the relationship among brain tumors,motor cortex and white matter fiber tracts,and contributes to preoperative comprehensive evaluation of brain tumors adjacent to the motion function area.