The role of hippocampal connectivity in mesial temporal lobe epilepsy (mTLE) remains poorly understood. The use of ex vivo hippocampal samples excised from patients with mTLE affords mesoscale diffusion magnetic resonance imaging (MRI) to identify individual cell layers, such as the pyramidal (PCL) and granule cell layers (GCL), which are thought to be impacted by seizure activity. Diffusion tensor imaging (DTI) of control (n = 3) and mTLE (n = 7) hippocampi on an 11.7 T MRI scanner allowed us to reveal intra‐hippocampal connectivity and evaluate how epilepsy affected mean (MD), axial (AD), and radial diffusivity (RD), as well as fractional anisotropy (FA). Regional measurements indicated a volume loss in the PCL of the cornu ammonis (CA) 1 subfield in mTLE patients compared to controls, which provided anatomical context. Diffusion measurements, as well as streamline density, were generally higher in mTLE patients compared to controls, potentially reflecting differences due to tissue fixation. mTLE measurements were more variable than controls. This variability was associated with disease severity, as indicated by a strong correlation (r = 0.87) between FA in the stratum radiatum and the frequency of seizures in patients. MD and RD of the PCL in subfields CA3 and CA4 also correlated strongly with disease severity. No correlation of MR measures with disease duration was evident. These results reveal the potential of mesoscale diffusion MRI to examine layer‐specific diffusion changes and connectivity to determine how these relate to clinical measures. Improving the visualization of intra‐hippocampal connectivity will advance the development of novel hypotheses about seizure networks.

中文翻译：

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离体细观扩散 MRI 与不受控制的内侧颞叶癫痫患者的癫痫发作频率相关。

海马连接在内侧颞叶癫痫 (mTLE) 中的作用仍然知之甚少。使用从 mTLE 患者身上切除的离体海马样本提供了中尺度扩散磁共振成像 (MRI) 来识别单个细胞层，例如锥体 (PCL) 和颗粒细胞层 (GCL)，它们被认为受到癫痫发作的影响活动。控制 ( n = 3) 和 mTLE ( n ) 的扩散张量成像 (DTI)= 7) 11.7 T MRI 扫描仪上的海马使我们能够揭示海马内连接并评估癫痫如何影响平均 (MD)、轴向 (AD) 和径向扩散率 (RD) 以及分数各向异性 (FA)。区域测量表明，与提供解剖背景的对照相比，mTLE 患者的羊角 (CA) 1 亚区的 PCL 体积损失。与对照组相比，mTLE 患者的扩散测量值以及流线密度通常更高，这可能反映了由于组织固定引起的差异。mTLE 测量比对照更具可变性。这种变异性与疾病严重程度相关，如强相关性所示（r= 0.87) 辐射层中的 FA 与患者癫痫发作的频率之间。子域 CA3 和 CA4 中 PCL 的 MD 和 RD 也与疾病严重程度密切相关。MR 测量值与病程之间没有明显的相关性。这些结果揭示了中尺度扩散 MRI 检查特定层扩散变化和连通性的潜力，以确定这些变化与临床测量的关系。改善海马内连接的可视化将推动关于癫痫网络的新假设的发展。