FUNCTIONAL MRI FOR NEUROSURGICAL PLANNING IN EPILEPSY

接受脑部病变手术切除的癫痫患者必须有某种形式的功能图，以确定是否可以在不造成功能缺陷的情况下切除病变。目前对这些患者的语言功能区进行定位的方法要么是空间受限的(例如，用WADA测试的半球定位)，要么是高度侵入性的(使用硬膜下电极的皮质刺激)。功能性磁共振成像(FMRI)有可能取代目前神经外科计划中使用的方法。它是完全非侵入性的，已经被证明能够检测大脑的功能区域。然而，基于大胆激活响应的标准回波平面成像fMRI方法存在空间分辨率低、对Bomicron静态磁场不均匀敏感等问题，导致图像几何失真和信号强度低。这些问题严重限制了功能磁共振成像为神经外科计划定位大脑活动的能力。该项目旨在改进功能磁共振成像方法，并对患者的功能磁共振语言标测和目前的金标准皮质刺激进行彻底的比较。这项研究将确定功能磁共振成像预测手术结果的能力。这些患者将使用皮质刺激和功能磁共振成像绘制语言区域图，并将在手术前和手术后进行行为研究，以衡量手术后可能出现的任何缺陷。方法学的发展将特别侧重于我们设计的新技术，以减少回声平面功能磁共振成像中的图像失真，同时提高空间分辨率，同时即使在存在场不均匀的情况下也能产生高度稳健的激活图。我们的方法包括修改图像采集策略，并结合新的后处理算法。这一创新计划将使手术规划所需的大脑功能区域得到高度可靠的定位。虽然重点是开发和验证用于癫痫神经外科计划的fMRI方法学，但技术发展将是一般性的，可以应用于任何功能性磁共振成像研究。这一项目的成功完成可能会使功能磁共振成像成为神经外科计划中大脑功能定位的主要来源，减少对侵入性标测技术的需求。

Epilepsy patients who are candidates for surgical resection of a brain lesion must have some form of functional mapping to determine if the lesion can be removed without creating a functional deficit. The current procedures for mapping language functional areas in these patients are either spatially limited (hemispheric mapping with the Wada test for example) or highly invasive (cortical stimulation using subdural electrodes). Functional MR imaging (fMRI) has the potential to replace the current methods used in Neurosurgical planning. It is completely noninvasive and has been shown to be able to detect functional brain regions. However, the standard echo planar imaging fMRI methods, based on the BOLD activation response, suffer from low spatial resolution, and a sensitivity to static Bomicron magnetic field inhomogeneities which lead to geometric image distortions and low signal intensity. These problems severely limit the ability of fMRI to localize brain activity for Neurosurgical planning. This project is designed to improve fMRI methodology and to perform a thorough comparison between fMRI language mapping and the current gold standard cortical stimulation in patients. This study will determine the ability of fMRI to predict surgical outcome. The patients will have language areas mapped using cortical stimulation and fMRI, and they will undergo behavioral studies pre- and post- surgery in order to measure any deficits that may arise post-surgery. The methodology development will specifically focus on novel techniques we have designed to reduce image distortion in echo planar fMRI, while increasing spatial resolution, and while producing highly robust activation maps even in the presence of field inhomogeneities. Our approach includes modifications to image acquisition strategies in conjunction with new post-processing algorithms. This innovative program will allow for highly robust localization of functional brain regions needed for surgical planning. While the emphasis is on the development and validation of fMRI methodology for Neurosurgical planning in epilepsy, the technical developments will be general and can be applied to any functional MR imaging study. Successful completion of this project may allow fMRI to be used as the primary source of functional localization in the brain for Neurosurgical planning reducing the need for invasive mapping techniques.