Assessment of cerebral microbleeds by susceptibility-weighted imaging at 3T in patients with end-stage organ failure

Purpose: Cerebral microbleeds (CMBs) are small rounded lesions representing cerebral hemosiderin deposits surrounded by macrophages that results from previous microhemorrhages. The aim of this study was to review the distribution of cerebral microbleeds in patients with end-stage organ failure and their association with specific end-stage organ failure risk factors. Materials and methods: Between August 2015 and June 2017, we evaluated 15 patients, 9 males, and 6 females, (mean age 65.5 years). Patients population was subdivided into three groups according to the organ failure: (a) chronic kidney failure (n = 8), (b) restrictive cardiomyopathy undergoing heart transplantation (n = 1), and (c) end-stage liver failure undergoing liver transplantation (n = 6). The MR exams were performed on a 3T MR unit and the SWI sequence was used for the detection of CMBs. CMBs were subdivided in supratentorial lobar distributed, supratentorial non-lobar distributed, and infratentorial distributed. Results: A total of 91 microbleeds were observed in 15 patients. Fifty-nine CMBs lesions (64.8%) had supratentorial lobar distribution, 17 CMBs lesions (18.8%) had supratentorial non-lobar distribution and the remaining 15 CMBs lesions (16.4%) were infratentorial distributed. An overall predominance of supratentorial multiple lobar localizations was found in all types of end-stage organ failure. The presence of CMBs was significantly correlated with age, hypertension, and specific end-stage organ failure risk factors (p < 0.001). Conclusions: CMBs are mostly founded in supratentorial lobar localization in end-stage organ failure. The improved detection of CMBs with SWI sequences may contribute to a more accurate identification of patients with cerebral risk factors to prevent complications during or after the organ transplantation

Brain-core temperature of patients before and after orthotopic liver transplantation assessed by DWI thermometry

To assess brain-core temperature of end-stage liver disease patients undergoing orthotopic liver transplantation (OLT) using a temperature measurement technique based on the apparent diffusion coefficient of the cerebrospinal fluid in the lateral ventricles

Assessment of Functional Connectome in End-Stage Organ Disease Patients After Life-Threatening Surgery

Purpose The purpose of this study was to assess the organization of intrinsic functional brain networks (functional connectome) in neurologically asymptomatic patients with end-stage organ disease who had undergone major surgery for life-threating conditions and compare it to a control group. Materials and Methods Resting-state functional magnetic resonance imaging (rest-fMRI) was performed in 10 adult, post-operative patients with end-stage organ disease. The patients (7 men, 3 women, mean age 57.9 ± 7.4 years) had undergone: n=4 coronary artery bypass graft for heart failure, n=2 orthotopic liver transplantation for non-alcoholic cirrhotic liver failure, n=3 mitral valve repair for heart failure, n=1 pancreaticoduodenectomy for pancreatic papillary tumor. Rest-fMRI was acquired within 48 hours after intensive care unit discharge. Structural brain MR imaging was acquired with T1-weighted, T2-weighted, diffusion weighted imaging, and susceptibility weighted imaging along with 3D isotropic T1-weighted MR images. MR examinations were performed on a 3T MR scanner (Discovery 750w, General Electric Healthcare, Milwaukee, WI, USA). Ten age- and sex-matched healthy controls were studied with the same protocol. Brain functional networks were analyzed by calculating the interregional correlation of low-frequency fluctuations in spontaneous brain activity. Weighted graph-based models were employed to topologically recognize reproducibly determined large-scale functional networks, including default mode, salience, dorsal attention, sensorimotor, visual and language networks using a seed-based approach with Functional Connectivity Toolbox (CONN) (https://web.conn-toolbox.org/) running under MatLab (The MathWorks Inc., Natick, MA, USA). A p-uncorrected < 0.0025 was used to threshold connectomes for voxel-wise paired statistical analysis to take in account the lateralization effect. Network comparisons were thresholded using a false discovery rate (FDR) cluster-level correction approach in patients and controls using the MatLab function “mafdr” for p-uncorrected <0.0025 obtaining the p-FDR < 0.077. Results Functional connectivity in patients and controls was successfully assessed for the default mode, salience, dorsal attention, sensorimotor, visual, and language networks of the brain. There was statistically significant (p <0.05) reduced connectivity between seeds in the default mode, salience, sensorimotor, and language networks in patients compared to controls (Fig. 1). No acute structural lesions were observed in patients at MR imaging. Conclusion Assessment of functional connectome in end-stage organ disease patients is feasible in routine clinical setting. Rest-fMRI can demonstrate reduced connectivity of several intrinsic functional networks in critically ill, post-operative patients and it may be a useful prognostic indicator of early and long-term clinical outcome. References Ma X, et al. Aberrant functional connectome in neurologically asymptomatic patients with end-stage renal disease. PloS One 2015;10:e0121085. Lariviere S, et al. Disrupted functional network integrity and flexibility after stroke: Relation to motor impairments. NeuroImage. Clinical 2018;19:883–891. Cheng Y, et al. Longitudinal Intrinsic Brain Activity Changes in Cirrhotic Patients before and One Month after Liver Transplantation. Korean Journal of Radiology, 2017;18,370–377. Zhang XD, et al. Long-and short-range functional connectivity density alteration in non-alcoholic cirrhotic patients one month after liver transplantation: A resting-state fMRI study. Brain Research, 2015;1620:177–187. Whitfield-Gabrieli S, Nieto-Castanon A. Conn: a functional connectivity toolbox for correlated and anticorrelated brain networks. Brain Connect. 2012; 2:125-141. Additional Video Material: https://youtu.be/15lzif0MOO

Statistical Approaches to Identify Pairwise and High-Order Brain Functional Connectivity Signatures on a Single-Subject Basis

Keeping up with the shift towards personalized neuroscience essentially requires the derivation of meaningful insights from individual brain signal recordings by analyzing the descriptive indexes of physio-pathological states through statistical methods that prioritize subject-specific differences under varying experimental conditions. Within this framework, the current study presents a methodology for assessing the value of the single-subject fingerprints of brain functional connectivity, assessed both by standard pairwise and novel high-order measures. Functional connectivity networks, which investigate the inter-relationships between pairs of brain regions, have long been a valuable tool for modeling the brain as a complex system. However, their usefulness is limited by their inability to detect high-order dependencies beyond pairwise correlations. In this study, by leveraging multivariate information theory, we confirm recent evidence suggesting that the brain contains a plethora of high-order, synergistic subsystems that would go unnoticed using a pairwise graph structure. The significance and variations across different conditions of functional pairwise and high-order interactions (HOIs) between groups of brain signals are statistically verified on an individual level through the utilization of surrogate and bootstrap data analyses. The approach is illustrated on the single-subject recordings of resting-state functional magnetic resonance imaging (rest-fMRI) signals acquired using a pediatric patient with hepatic encephalopathy associated with a portosystemic shunt and undergoing liver vascular shunt correction. Our results show that (i) the proposed single-subject analysis may have remarkable clinical relevance for subject-specific investigations and treatment planning, and (ii) the possibility of investigating brain connectivity and its post-treatment functional developments at a high-order level may be essential to fully capture the complexity and modalities of the recovery