Department of Neurosurgery, Thomas Jefferson University, Philadelphia, PA, USA.
Jefferson Integrated Magnetic Resonance Imaging Center, Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
Sci Rep. 2019 Jan 18;9(1):215. doi: 10.1038/s41598-018-36818-x.
Imaging in the field of epilepsy surgery remains an essential tool in terms of its ability to identify regions where the seizure focus might present as a resectable area. However, in many instances, an obvious structural abnormality is not visualized. This has created the opportunity for new approaches and imaging innovation in the field of epilepsy, such as with Diffusion Tensor Imaging (DTI) and Diffusion Tensor Tractography (DTT). In this study, we aim to evaluate the use of DTI and DTT as a predictive model in the field of epilepsy, specifically Temporal Lobe Epilepsy (TLE), and correlate their clinical significance with respect to postsurgical outcomes. A hemispheric based analysis was used to compare the tract density, as well as DTI indices of the specific regions of interest from the pathologic hemisphere to the healthy hemisphere in TLE patients. A total of 22 patients with TLE (12 males, 10 females, 22-57 age range) underwent either a craniotomy, Anterior Temporal Lobectomy (ATL), or a less invasive method of Selective Laser Amygdalohippocampectomy (SLAH) and were imaged using 3.0 T Philips Achieva MR scanner. Of the participants, 12 underwent SLAH while 10 underwent ATL. The study was approved by the institutional review board of Thomas Jefferson University Hospital. Informed consent was obtained from all patients. All patients had a diagnosis of TLE according to standard clinical criteria. DTI images were acquired axially in the same anatomical location prescribed for the T1-weighted images. The raw data set consisting of diffusion volumes were first corrected for eddy current distortions and motion artifacts. Various DTI indices such as Fractional Anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD) were estimated and co-registered to the brain parcellation map obtained by freesurfer. 16 consolidated cortical and subcortical regions were selected as regions of interest (ROIs) by a functional neurosurgeon and DTI values for each ROI were calculated and compared with the corresponding ROI in the opposite hemisphere. Also, track density imaging (TDI) of 68 white matter parcels were generated using fiber orientation distribution (FOD) based deterministic fiber tracking and compared with contralateral side of the brain in each epileptic group: left mesial temporal sclerosis (LMTS) and right MTS (RMTS)). In patients with LMTS, MD and RD values of the left hippocampus decreased significantly using two-tailed t-test (p = 0.03 and p = 0.01 respectively) compared to the right hippocampus. Also, RD showed a marginally significant decrease in left amygdala (p = 0.05). DTT analysis in LMTS shows a marginally significant decrease in the left white matter supramarginal parcel (p = 0.05). In patients with RMTS, FA showed a significant decrease in the ipsilateral mesial temporal lobe (p = 0.02), parahippocampal area (p = 0.03) and thalamus (p = 0.006). RD showed a marginally significant increase in the ipsilateral hippocampus (p = 0.05) and a significant increase in the ipsilateral parahippocampal area (p = 0.03). Also, tract density of the ipsilateral white matter inferior parietal parcel showed a marginally significant increase compared to the contralateral side (p = 0.05). With respect to postsurgical outcomes, we found an association between residual seizures and tract density in five white matter segments including ipsilateral lingual (p = 0.04), ipsilateral temporal pole (p = 0.007), ipsilateral pars opercularis (p = 0.03), ipsilateral inferior parietal (p = 0.04) and contralateral frontal pole (p = 0.04). These results may have the potential to be developed into imaging prognostic markers of postoperative outcomes and provide new insights for why some patients with TLE continue to experience postoperative seizures if pathological/clinical correlates are further confirmed.
癫痫外科领域的影像学仍然是识别致痫灶可切除区域的重要工具。然而,在许多情况下,并没有发现明显的结构性异常。这为癫痫领域的新方法和影像学创新创造了机会,例如弥散张量成像(DTI)和弥散张量纤维束示踪成像(DTT)。在这项研究中,我们旨在评估 DTI 和 DTT 在癫痫领域,特别是颞叶癫痫(TLE)中的预测模型,并将其临床意义与术后结果相关联。我们使用半球分析方法比较了 TLE 患者病变半球和对侧半球特定感兴趣区域的束密度以及 DTI 指数。共 22 例 TLE 患者(男 12 例,女 10 例,年龄 22-57 岁)接受了开颅术、前颞叶切除术(ATL)或选择性激光杏仁核海马切除术(SLAH),并使用 3.0T Philips Achieva MR 扫描仪进行成像。其中 12 例患者接受了 SLAH,10 例患者接受了 ATL。该研究得到了托马斯杰斐逊大学医院机构审查委员会的批准。所有患者均获得了知情同意。所有患者均根据标准临床标准诊断为 TLE。DTI 图像在与 T1 加权图像相同的解剖位置轴向采集。首先对包含扩散体积的原始数据集进行涡流失真和运动伪影校正。估计了各种 DTI 指数,如分数各向异性(FA)、平均扩散度(MD)、径向扩散度(RD)和轴向扩散度(AD),并与通过 freesurfer 获得的脑分割图谱配准。由功能神经外科医生选择 16 个皮质和皮质下整合区域作为感兴趣区(ROI),并计算每个 ROI 的 DTI 值,并与对侧半球的相应 ROI 进行比较。此外,使用基于纤维方向分布(FOD)的确定性纤维跟踪生成了 68 个白质束的轨迹密度成像(TDI),并在每个癫痫组的大脑对侧进行了比较:左侧内侧颞叶硬化(LMTS)和右侧内侧颞叶硬化(RMTS)。在 LMTS 患者中,左海马的 MD 和 RD 值在双侧比较中显著降低(p=0.03 和 p=0.01)。此外,左杏仁核的 RD 值也略有显著降低(p=0.05)。LMTS 的 DTT 分析显示左额上回白质超边缘包的 RD 值略有显著降低(p=0.05)。在 RMTS 患者中,FA 值在同侧内侧颞叶(p=0.02)、海马旁回(p=0.03)和丘脑(p=0.006)显著降低。RD 值在同侧海马(p=0.05)和同侧海马旁回(p=0.03)有轻微显著增加。此外,同侧下顶叶白质的束密度与对侧相比略有显著增加(p=0.05)。关于术后结果,我们发现 5 个白质节段的残余癫痫与束密度之间存在关联,包括同侧舌回(p=0.04)、同侧颞极(p=0.007)、同侧额下回(p=0.03)、同侧下顶叶(p=0.04)和对侧额极(p=0.04)。如果病理/临床相关性进一步得到证实,这些结果可能有潜力发展成为术后结果的影像学预后标志物,并为为什么一些 TLE 患者在术后仍继续出现癫痫提供新的见解。
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