Chen Hua-Jun, Zhang Xiao-Hong, Shi Jia-Yan, Jiang Shao-Fan, Sun Yi-Fan, Zhang Ling, Li Dan, Chen Rong
Department of Radiology, Fujian Medical University Union Hospital, Fuzhou, China.
Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Front Neuroanat. 2021 Feb 25;15:592772. doi: 10.3389/fnana.2021.592772. eCollection 2021.
Numerous studies have demonstrated thalamus-related structural, functional, and metabolic abnormalities in minimal hepatic encephalopathy (MHE). We conducted the first study to investigate thalamic structural connectivity alterations in MHE.
Diffusion tensor imaging (DTI)-based probabilistic tractography was employed to determine the structural linkage between the thalamus and cortical/subcortical regions in 52 cirrhotic patients [22 with MHE; 30 without MHE (NHE)] and 30 controls. We measured these thalamic connections, which included connectivity strength (CS), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), and then compared these among the three groups. Neurocognitive assessment was also performed. Correlation analysis was conducted to investigate the relationship between neurocognitive performance and the above measurements. Classification analysis was performed to determine whether thalamic connection measurements can distinguish MHE from NHE.
The probabilistic tractography revealed thalamic structural connections, which were disrupted in cirrhotic patients (as reflected by a decrease in CS/FA and an increase in MD/AD/RD). Abnormal thalamic connections primarily involved the prefrontal cortex, sensorimotor cortex, parietal cortex, medial temporal cortex and hippocampus, and striatum. Thalamic connectivity abnormalities deteriorated from NHE to MHE, and they were correlated with patients' neurocognitive performance. The moderate classification accuracy was obtained using CS and MD as discriminating indexes.
Our results demonstrated the altered thalamic structural connectivity involving both cortical and subcortical regions in MHE, which could be regarded as representative of MHE-related widespread impairments in white matter pathways. The disturbed thalamic connectivity may underlie the mechanism of cognitive deficits in MHE and may potentially be utilized as a biomarker for diagnosing MHE and in monitoring disease progression. In addition to thalamic-cortical/subcortical connections, further studies are recommended to explore the structural alterations in other white matter pathways in MHE.
大量研究已证明，在轻微肝性脑病（MHE）中存在与丘脑相关的结构、功能及代谢异常。我们开展了首项研究，以探究MHE患者丘脑的结构连接改变情况。
采用基于扩散张量成像（DTI）的概率性纤维束成像技术，确定52例肝硬化患者（22例MHE患者；30例无MHE患者（NHE））及30名对照者丘脑与皮质/皮质下区域之间的结构联系。我们测量了这些丘脑连接，包括连接强度（CS）、各向异性分数（FA）、平均扩散率（MD）、轴向扩散率（AD）和径向扩散率（RD），然后比较三组之间的这些指标。还进行了神经认知评估。进行相关性分析，以研究神经认知表现与上述测量指标之间的关系。进行分类分析，以确定丘脑连接测量指标能否区分MHE与NHE。
概率性纤维束成像显示，肝硬化患者的丘脑结构连接中断（表现为CS/FA降低及MD/AD/RD升高）。异常的丘脑连接主要累及前额叶皮质、感觉运动皮质、顶叶皮质、内侧颞叶皮质和海马体以及纹状体。丘脑连接异常从NHE到MHE逐渐恶化，且与患者的神经认知表现相关。以CS和MD作为判别指标时，分类准确率中等。
我们的结果表明，MHE患者丘脑的结构连接发生改变，涉及皮质和皮质下区域，这可被视为MHE相关的白质通路广泛损伤的代表。丘脑连接紊乱可能是MHE认知缺陷机制的基础，并且可能潜在地用作诊断MHE及监测疾病进展的生物标志物。除了丘脑-皮质/皮质下连接外，建议进一步研究探索MHE中其他白质通路的结构改变。
