Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY 10016, USA.
Department of Neurosurgery, New York University School of Medicine, New York, NY 10016, USA.
Neuroimage. 2012 Oct 15;63(1):157-165. doi: 10.1016/j.neuroimage.2012.06.039. Epub 2012 Jun 30.
Intracranial electrode arrays are routinely used in the pre-surgical evaluation of patients with medically refractory epilepsy, and recordings from these electrodes have been increasingly employed in human cognitive neurophysiology due to their high spatial and temporal resolution. For both researchers and clinicians, it is critical to localize electrode positions relative to the subject-specific neuroanatomy. In many centers, a post-implantation MRI is utilized for electrode detection because of its higher sensitivity for surgical complications and the absence of radiation. However, magnetic susceptibility artifacts surrounding each electrode prohibit unambiguous detection of individual electrodes, especially those that are embedded within dense grid arrays. Here, we present an efficient method to accurately localize intracranial electrode arrays based on pre- and post-implantation MR images that incorporates array geometry and the individual's cortical surface. Electrodes are directly visualized relative to the underlying gyral anatomy of the reconstructed cortical surface of individual patients. Validation of this approach shows high spatial accuracy of the localized electrode positions (mean of 0.96 mm ± 0.81 mm for 271 electrodes across 8 patients). Minimal user input, short processing time, and utilization of radiation-free imaging are strong incentives to incorporate quantitatively accurate localization of intracranial electrode arrays with MRI for research and clinical purposes. Co-registration to a standard brain atlas further allows inter-subject comparisons and relation of intracranial EEG findings to the larger body of neuroimaging literature.
颅内电极阵列常用于药物难治性癫痫患者的术前评估，由于其具有较高的空间和时间分辨率，这些电极的记录在人类认知神经生理学中得到了越来越多的应用。对于研究人员和临床医生来说，将电极位置相对于特定个体的神经解剖结构进行定位至关重要。在许多中心，由于术后 MRI 对手术并发症具有更高的敏感性，并且没有辐射，因此会利用术后 MRI 来检测电极。然而，每个电极周围的磁敏感性伪影会妨碍对单个电极的明确检测，尤其是那些嵌入在密集网格阵列中的电极。在这里，我们提出了一种基于植入前后 MRI 图像的有效方法，该方法结合了阵列几何形状和个体的皮质表面，可准确地定位颅内电极阵列。电极可以直接相对于个体患者皮质表面重建的皮质下回结构进行可视化。该方法的验证结果表明，定位电极位置的空间精度很高（8 名患者的 271 个电极的平均误差为 0.96 毫米±0.81 毫米）。这种方法需要的用户输入很少，处理时间短，并且使用无辐射成像，这为在研究和临床中利用 MRI 对颅内电极阵列进行定量精确定位提供了强有力的激励。与标准脑图谱的配准进一步允许进行个体间的比较，并将颅内 EEG 结果与更广泛的神经影像学文献联系起来。
