基于成分的 EEG-fMRI 定位癫痫灶的一致性定量测定。
Quantitative determination of concordance in localizing epileptic focus by component-based EEG-fMRI.
机构信息
CIPCE, School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran; Seaman Family MR Research Centre, University of Calgary, Calgary, Alberta, Canada.
Department of Biomedical Engineering, George Washington University, Washington D.C., USA.
出版信息
Comput Methods Programs Biomed. 2019 Aug;177:231-241. doi: 10.1016/j.cmpb.2019.06.003. Epub 2019 Jun 5.
BACKGROUND AND OBJECTIVE
Accurate seizure onset zone (SOZ) localization is an essential step in pre-surgical assessment of patients with refractory focal epilepsy. Complex pathophysiology of epileptic cerebral structures, seizure types and frequencies have not been considered as influential features for accurate identification of SOZ using EEG-fMRI. There is a crucial need to quantitatively measure concordance between presumed SOZ and IED-related BOLD response in different brain regions to improve SOZ delineation.
METHODS
A novel component-based EEG-fMRI approach is proposed to measure physical distance between BOLD clusters and selected component dipole location using patient-specific high resolution anatomical images. The method is applied on 18 patients with refractory focal epilepsy to localize epileptic focus and determine concordance quantitatively and compare between maximum BOLD cluster with identified component dipole. To measure concordance, distance from a voxel with maximal z-score of maximum BOLD to center of extracted component dipole is measured.
RESULTS
BOLD clusters to spikes distances for concordant (<25 mm), partially concordant (25-50 mm), and discordant (>50 mm) groups were significantly different (p < 0.0001). The results showed full concordance in 17 IED types (17.85 ± 4.69 mm), partial concordance in 4 (36.47 ± 8.84 mm), and nodiscordance, which is a significant rise compared to the existing literature. The proposed method is premised on the cross-correlation between the spike template outside the scanner and the highly-ranked extracted components. It successfully surpasses the limitations of conventional EEG-fMRI studies which are largely dependent on inside-scanner spikes. More significantly, the proposed method improves localization accuracy to 97% which marks a dramatic rise compared to conventional works.
CONCLUSIONS
This study demonstrated that BOLD changes were related to epileptic spikes in different brain regions in patients with refractory focal epilepsy. In a systematic quantitative approach, concordance levels based on the distance between center of maximum BOLD cluster and dipole were determined by component-based EEG-fMRI method. Therefore, component-based EEG-fMRI can be considered as a reliable predictor of SOZ in patients with focal epilepsy and included as part of clinical evaluation for patients with medically resistant epilepsy.
背景与目的
准确的癫痫起始区（SOZ）定位是评估耐药性局灶性癫痫患者的术前评估的重要步骤。然而，癫痫脑结构、发作类型和频率的复杂病理生理学尚未被认为是使用 EEG-fMRI 准确识别 SOZ 的有影响的特征。因此，迫切需要定量测量不同脑区中假定的 SOZ 与与 IED 相关的 BOLD 反应之间的一致性，以改善 SOZ 描绘。
方法
本研究提出了一种新的基于组件的 EEG-fMRI 方法，该方法使用患者特定的高分辨率解剖图像，通过测量 BOLD 簇与选定组件偶极子位置之间的物理距离，来定量测量假定的 SOZ 与与 IED 相关的 BOLD 反应之间的一致性。该方法应用于 18 例耐药性局灶性癫痫患者，以定位癫痫灶并定量确定一致性，并将最大 BOLD 簇与识别的组件偶极子进行比较。为了测量一致性，测量具有最大 BOLD 的 z 分数的体素到提取组件偶极子中心的距离。
结果
对于一致性（<25mm）、部分一致性（25-50mm）和不一致性（>50mm）组，BOLD 簇与棘波的距离差异有统计学意义（p<0.0001）。结果显示，在 17 种 IED 类型中存在完全一致性（17.85±4.69mm），4 种存在部分一致性（36.47±8.84mm），不存在不一致性，与现有文献相比，这是一个显著的提高。该方法基于在扫描仪外的棘波模板与高排名提取组件之间的互相关。它成功地克服了传统 EEG-fMRI 研究的局限性，这些研究在很大程度上依赖于扫描仪内的棘波。更重要的是，该方法将定位准确性提高到 97%，与传统方法相比有了显著提高。
结论
本研究表明，难治性局灶性癫痫患者不同脑区的 BOLD 变化与癫痫棘波有关。在系统的定量方法中，基于最大 BOLD 簇和偶极子中心之间的距离，确定基于组件的 EEG-fMRI 方法的一致性水平。因此，基于组件的 EEG-fMRI 可以作为局灶性癫痫患者 SOZ 的可靠预测因子，并作为对耐药性癫痫患者进行临床评估的一部分。
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