FUNCTIONAL MRI FOR NEUROSURGICAL PLANNING IN EPILEPSY

需要手术切除脑病变的癫痫患者必须进行某种形式的功能测绘，以确定是否可以在不造成功能缺陷的情况下切除病变。目前在这些患者中绘制语言功能区地图的方法要么是空间有限的（例如使用Wada测试绘制半球地图），要么是高度侵入性的（使用硬膜下电极进行皮层刺激）。功能磁共振成像（fMRI）有可能取代目前在神经外科计划中使用的方法。它是完全无创的，并且已经被证明能够检测到大脑的功能区域。然而，基于BOLD激活响应的标准回波平面成像fMRI方法存在空间分辨率低，且对静态波美克隆磁场不均匀性敏感，导致几何图像失真和信号强度低的问题。这些问题严重限制了功能磁共振成像在神经外科手术计划中定位大脑活动的能力。本项目旨在改进功能磁共振成像方法，并在功能磁共振成像语言映射与当前患者的金标准皮质刺激之间进行彻底的比较。本研究将确定功能磁共振成像预测手术结果的能力。患者将使用皮质刺激和功能磁共振成像绘制语言区域图，他们将在术前和术后接受行为研究，以测量术后可能出现的任何缺陷。方法开发将特别关注我们设计的新技术，以减少回波平面fMRI中的图像失真，同时提高空间分辨率，即使在存在场不均匀性的情况下也能产生高度鲁棒的激活图。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。这个创新的程序将允许高度稳健的定位手术计划所需的脑功能区域。虽然重点是开发和验证癫痫神经外科计划的功能磁共振成像方法，但技术发展将是一般性的，可以应用于任何功能磁共振成像研究。该项目的成功完成可能使fMRI成为神经外科计划中大脑功能定位的主要来源，减少了对侵入性测绘技术的需求。

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.