Resting-state Functional Magnetic Resonance Imaging Study On The Brain Function Changes One Month After Liver Transplantation

Purpose: To investigate the brain function changes in cirrhotic patients before and one month after Liver transplantation(LT) by using resting state functional MRI(rs-fMRI). To evaluate the regional characteristics using regional homogeneity(Re Ho)method, the whole brain connectivity network using long- and short-range functional connectivity density(FCD), and the default mode network(DMN) using seed-based functional connectivity analysis. To explore the relationship between the brain function alterations and cognitive changes.PartⅠReHo changes one month after LT Methods: Twenty-six LT candidates and 26 age-, gender-, and education-matched healthy controls(HCs) were recruited, all the patients and HCs performed rs-fMRI examinations. Twelve of 26 patients received the repeated MRI examination one month after LT. ReHo values were calculated to evaluate spontaneous brain activity and were compared between groups. Correlations between the change of ReHo(ΔReHo) with the change of clinical indexes pre- and post-LT were evaluated as well.Results: One month after LT, the post-LT group showed increased ReHo values in the bilateral inferior frontal gyrus(IFG), right inferior parietal lobule(IPL), right supplementary motor area(SMA), right superior temporal gyrus(STG) and left middle frontal gyrus(MFG), when compared with the pre-LT group. While compared to controls, post-LT patients still showed multiple brain regions with abnormal ReHo,such as decreased ReHo in the right precuneus, right SMA and increased in bilateral temporal pole, left caudate, left MFG, and right STG. In addition, we also found change of digit symbol test(ΔDST) correlated with ΔReHo in the right SMA, STG and IFG.PartⅡ FCD changes one month after LT Methods: Twenty six LT candidates and 26 age-, gender-, and education-matched healthy controls(HCs) were recruited, all the patients and HCs performed rs-fMRI examinations. Twelve of 26 patients received the repeated MRI examination one month after LT. The long- and short-range FCD derived from degree centrality calculation were compared between groups. Correlations between the change of the long- and short-range FCD(ΔFCD) with the change of clinical indexes pre- andpost-LT were evaluated as well. Results: One month after LT, the post-LT group showed reduced long-range FCD in right posterior cingulate cortex(PCC) and Left MFG, and reduced short-range FCD in right precuneus(PCu), when compared with the control group. While compared with the pre-LT group, the post-LT group showed reduced long-range FCD in right rectus gyrus(REC) and left medial prefrontal cortex(MPFC), and reduced short-range FCD in left middle temporal gyrus(MTG). In addition, we also foundΔDST correlated with long-rangeΔFCD in right precentral gyrus(preCG) and right SMA.PartⅢ Default mode network changes one month after LT Methods: Eighteen cirrhotic patients as transplant candidates and 20 healthy controls were included in this study. All the patients underwent rs-fMRI examination before and one month after LT. Seed-based functional connectivity(FC) analysis was used to isolate the DMN. The PCC was chosen as seed region for the DMN map. Maps of the DMN were compared among the groups. Values of Z reflecting the functional connectivity of 3 groups were obtained. Two-sample t-test was performed to explore the DMN difference between cirrhotic patients and controls, and we used paired t tests to examine for any differences in functional connectivity before and after LT. Pearson correlation analysis was performed to explore the relationship between the changes of functional connectivity with that of clinical indexes and neuropsychological test scores pre- and post-LT. Results: According to paired t test, post-LT patients showed increased FC in left MPFC, while decreased FC in left PCu and left lateral temporal cortex. Compared to healthy controls, pre-LT patients showed decreased FC in the right PCu, bilateral MPFC, bilateral IPL, and bilateral lateral temporal cortex(LTC),and post-LT patients showed decreased FC in right PCu, left PCC, bilateral IPL, and bilateral LTC. Pearson correlation analysis revealed positively correlation between the changes of functional connectivity in left MPFC with that of DST.Conclusion:(1) LT has favorable effect on cognitive function in cirrhotic patient,which can be reflected by ReHo and FCD alterations;(2) Both ReHo and FCD methods showed some brain function abnormalities persisted after LT, indicating complete cognitive function restoration may need a longer time;(3) The DMN FC of post-LT patients still lower than that of healthy controls one month after LT. The left medial prefrontal cortex was the first brain region that showed increased FC, whilethe FC of some regions continued to decrease, suggesting that brain function reorganization can continue after LT;(4) Rs-fMRI can be used to observe the brain function changes in post-LT patients.