Altered topological properties of gray matter structural covariance networks inminimal hepatic encephalopathy
Tian-Xiu Zou1 and Hua-Jun Chen1

1Department of Radiology, Fujian Medical University Union Hospital, Fuzhou, China


Despite the abnormal structural findings in cirrhotic patients with MHE, previous studies have only focused on regional structural changes in cirrhosis and did not consider brain network-level architecture. Recent progress in structural MRI analysis has facilitated the development of a human brain structural network model that is based on statistical correlations of morphological descriptors, including the thickness of the cortex or regional gray matter volume (RGMV). We investigated the topological alterations involving brain structural covariance networks in MHE patients for the first time. Our results suggest that MHE patients exhibit an unoptimizable architecture involving the gray matter structural covariance network and provide structural evidence supporting that MHE is a neurological complication related to disrupted neural networks.


Liver cirrhosis commonly induces brain structural impairments that are associated with neurological complications [e.g., minimal hepatic encephalopathy (MHE)], but the topological characteristics of the brain structural network are still less well understood in cirrhotic patients with MHE. This study aimed to conduct the first investigati on on the topological alterations of brain structural covariance networks in MHE.



MRI scanning was performed using a MAGNETOM Prisma 3.0T scanner (Siemens Healthcare, Erlangen, Germany) with a 64-channel head coil. Twenty-two cirrhotic patients with MHE and 22 healthy controls (HCs) underwent high-resolution T1-weighted imaging. We calculated the gray matter volume of 90 brain regions using an automated anatomical labeling (AAL) template, followed by construction of gray matter structural covariance networks by thresholding interregional structural correlation matrices as well as graph theoretical analysis.


MHE patients showed abnormal small-world properties of the brain structural covariance network, i.e., decreased clustering coefficient and characteristic path length and lower small-worldness parameters, which indicated a tendency toward more random architecture. In addition, MHE patients lost hubs in the prefrontal and parietal regions, although they had new hubs in the temporal and occipital regions. Compared toHC, MHE patients had decreased regional degree/betweenness involving several regions, primarily the prefrontal and parietal lobes, motor region, insula, and thalamus.In addition, the MHE group also showed increased degree/betweenness in the occipital lobe and hippocampus.


These results suggest that MHE leads to altered coordination patterns of gray matter morphology and provide structural evidence supporting the idea that MHE is a neurological complication related to disrupted neural networks.


This study was funded by the grants from the National Natural Science Foundation of China (No.81501450), Fujian Provincial Science Fund for Distinguished Young Scholars (No. 2018J06023), Fujian Provincial Program for Distinguished Young Scholars (No.2017B023), and Fujian Provincial Health Commission Project for Scientific Research Talents (2018-ZQN-28).


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The interregional correlations matrix in healthy control (HC) and minimal hepatic encephalopathy (MHE) groups. The color bar represents correlation strength. These matrices indicate the maps thresholded at the minimum network density (=12%), wherein the networks depicted full connectivity (without fragmented nodes).

Small-world properties of the gray matter structural covariance network of minimal hepatic encephalopathy (MHE) patients compared to healthy controls (HC), using various network densities (0.12~0.50).

Network hubs in healthy controls (HCs) and patients with minimal hepatic encephalopathy (MHE). The labeled nodes represent network hubs. The hubs that were common in two groups include the left ORBsupmed and right SFGmed. The hubs specific to HC include the bilateral SFGdor and ORBinf, left SFGmed, MFG, PreCG, TPOsup, INS, ROL and REC, and right ORBsup, ACG, IPL and ANG. The hubs specific to MHE patients include the bilateral IFGtriang and DCG, left MOG, ORBsup and CAL, and right ORBsupmed, MFG, HIP, LING, ITG and HES.

Brain regions depicting significant alterations in nodal degree and betweenness in the structural covariance network of the gray matter that was thresholded to a minimum density of full connectivity. The color bar indicates the log(1/p value). The warm color signifies regions with higher nodal betweenness or degree among healthy controls (HCs) relative to minimal hepatic encephalopathy (MHE) patients, whereas the cool color represents areas with greater nodal betweenness or degree in patients with MHE compared to the HCs.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)