Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada; Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada.
Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada.
Neuroimage. 2018 Nov 15;182:294-303. doi: 10.1016/j.neuroimage.2017.06.002. Epub 2017 Jun 3.
The majority of MRI studies in temporal lobe epilepsy (TLE) have utilized morphometry to map widespread cortical alterations. Morphological markers, such as cortical thickness or grey matter density, reflect combinations of biological events largely driven by overall cortical geometry rather than intracortical tissue properties. Because of its sensitivity to intracortical myelin, quantitative measurement of longitudinal relaxation time (qT) provides and an in vivo proxy for cortical microstructure. Here, we mapped the regional distribution of qT in a consecutive cohort of 24 TLE patients and 20 healthy controls. Compared to controls, patients presented with a strictly ipsilateral distribution of qT increases in temporopolar, parahippocampal and orbitofrontal cortices. Supervised statistical learning applied to qT maps could lateralize the seizure focus in 92% of patients. Intracortical profiling of qT along streamlines perpendicular to the cortical mantle revealed marked effects in upper levels that tapered off at the white matter interface. Findings remained robust after correction for cortical thickness and interface blurring, suggesting independence from previously reported morphological anomalies in this disorder. Mapping of qT along hippocampal subfield surfaces revealed marked increases in anterior portions of the ipsilateral CA1-3 and DG that were also robust against correction for atrophy. Notably, in operated patients, qualitative histopathological analysis of myelin stains in resected hippocampal specimens confirmed disrupted internal architecture and fiber organization. Both hippocampal and neocortical qT anomalies were more severe in patients with early disease onset. Finally, analysis of resting-state connectivity from regions of qT increases revealed altered intrinsic functional network embedding in patients, particularly to prefrontal networks. Analysis of qT suggests a preferential susceptibility of ipsilateral limbic cortices to microstructural damage, possibly related to disrupted myeloarchitecture. These alterations may reflect atypical neurodevelopment and affect the integrity of fronto-limbic functional networks.
大多数颞叶癫痫 (TLE) 的 MRI 研究都利用形态计量学来绘制广泛的皮质改变图。形态学标志物，如皮质厚度或灰质密度，反映了生物事件的组合，这些组合主要由皮质整体几何形状驱动，而不是由皮质内组织特性驱动。由于其对皮质内髓鞘的敏感性，纵向弛豫时间 (qT) 的定量测量为皮质微观结构提供了活体代理。在这里，我们在连续的 24 例 TLE 患者和 20 名健康对照者中绘制了 qT 的区域分布。与对照组相比，患者在颞极、海马旁回和眶额皮质中表现出严格的同侧 qT 增加分布。应用于 qT 图谱的监督统计学习可以在 92%的患者中对致痫灶进行侧化。沿着与皮质帽垂直的流线对 qT 进行皮质内分析显示，在上层有明显的影响，在白质界面处逐渐减弱。在对皮质厚度和界面模糊进行校正后，这些发现仍然很稳健，表明与该疾病中先前报道的形态异常无关。沿着海马子区表面绘制 qT 显示，同侧 CA1-3 和 DG 的前部部分明显增加，并且在对萎缩进行校正后仍然很稳健。值得注意的是，在手术患者中，对切除海马标本中的髓鞘染色进行定性组织病理学分析证实了内部结构和纤维组织的破坏。在疾病早期发病的患者中，海马和新皮质 qT 异常更为严重。最后，对 qT 增加区域的静息状态连接进行分析显示，患者的内在功能网络嵌入发生改变，特别是与前额叶网络相关的改变。qT 分析表明，同侧边缘皮质对微观结构损伤的易感性增加，这可能与髓鞘结构的破坏有关。这些改变可能反映了非典型的神经发育，并影响额 - 边缘功能网络的完整性。
