High resolution in-vivo diffusion imaging of the human hippocampus

Treit, Sarah; Steve, Trevor A.; Gross, Donald; Beaulieu, Christian

doi:10.1016/j.neuroimage.2018.01.034

Cited by 29 publications

(32 citation statements)

References 44 publications

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“…Although prior literature contends that the hippocampus may be particularly vulnerable to anoxia, 3 we did not identify preferential ABI in the hippocampus. However, it possible that these clinical diffusion-weighted scans, which poorly discriminate mesial temporal structures, 45 had insufficient resolution to fully assess hippocampal ABI.…”

Section: Discussionmentioning

confidence: 99%

Regional Distribution of Brain Injury After Cardiac Arrest

et al. 2022

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Background and Objectives:Disorders of consciousness, EEG background suppression and epileptic seizures are associated with poor outcome after cardiac arrest. Our objective was to identify the distribution of diffusion MRI-measured anoxic brain injury after cardiac arrest and to define the regional correlates of disorders of consciousness, EEG background suppression, and seizures.Methods:We analyzed patients from a single-center database of unresponsive patients who underwent diffusion MRI following cardiac arrest (n=204). We classified each patient based on recovery of consciousness (command-following) before discharge, the most continuous EEG background (burst suppression versus continuous), and the presence or absence of seizures. Anoxic brain injury was measured using the apparent diffusion coefficient (ADC) signal. We identified ADC abnormalities relative to control subjects without cardiac arrest (n=48) and used voxel lesion symptom mapping to identify regional associations with disorders of consciousness, EEG background suppression, and seizures. We then used a bootstrapped lasso regression procedure to identify robust, multivariate regional associations with each outcome variable. Finally, using area under receiver operating characteristic curves, we then compared the classification ability of the strongest regional associations to that of brain-wide summary measures.Results:Compared to controls, cardiac arrest patients demonstrated ADC signal reduction most significant in the occipital lobes. Disorders of consciousness were associated with reduced ADC most prominently in the occipital lobes, but also in deep structures. Regional injury more accurately classified patients with disorders of consciousness than whole-brain injury. Background suppression mapped to a similar set of brain regions, but regional injury could no better classify patients than whole-brain measures. Seizures were less common in patients with more severe anoxic injury, particularly in those with injury to the lateral temporal white matter.Discussion:Anoxic brain injury was most prevalent in posterior cerebral regions, and this regional pattern of injury was a better predictor of disorders of consciousness than whole-brain injury measures. EEG background suppression lacked a specific regional association, but patients with injury to the temporal lobe were less likely to have seizures. Regional patterns of anoxic brain injury are relevant to the clinical and electrographic sequelae of cardiac arrest and may hold importance for prognosis.Classification of Evidence:This study provides Class IV evidence that disorders of consciousness after cardiac arrest are associated with widely lower ADC values on diffusion MRI and are most strongly associated with reductions in occipital ADC.

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Section: Discussionmentioning

confidence: 99%

Regional Distribution of Brain Injury After Cardiac Arrest

et al. 2022

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“…Another relevant limiting point refers to the complex structure of the hippocampus itself and its consequences for the optimal number of clusters. The human hippocampus is characterized by angulation and a variable number of digitations (Ding and Van Hoesen 2015;Treit et al 2018;Wisse et al 2012). Both features could have influenced our results in terms of the optimal number of clusters.…”

Section: Limitationsmentioning

confidence: 99%

“…Due to the limited spatial resolution of MRI data, we may have missed differences in connectivity profiles of conflated subfields in the posterior hippocampus hence leading to a single tail cluster in the present study. Additionally, hippocampal gyrification, known as digitations, vary between individuals and have been previously discussed as a possible factor for inter-individual variability in the hippocampus (Chang et al 2018;DeKraker et al 2018;Ding and Van Hoesen 2015;Treit et al 2018). How this affects cognition and psychopathology (Oppenheim et al 1998) and whether different digitations have different connectivity profiles and hence could influence clustering pattern is still unclear.…”

Section: Limitationsmentioning

confidence: 99%

Multimodal Parcellations and Extensive Behavioral Profiling Tackling the Hippocampus Gradient

et al. 2019

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The hippocampus displays a complex organization and function that is perturbed in many neuropathologies. Histological work revealed a complex arrangement of subfields along the medial–lateral and the ventral–dorsal dimension, which contrasts with the anterior–posterior functional differentiation. The variety of maps has raised the need for an integrative multimodal view. We applied connectivity-based parcellation to 1) intrinsic connectivity 2) task-based connectivity, and 3) structural covariance, as complementary windows into structural and functional differentiation of the hippocampus. Strikingly, while functional properties (i.e., intrinsic and task-based) revealed similar partitions dominated by an anterior–posterior organization, structural covariance exhibited a hybrid pattern reflecting both functional and cytoarchitectonic subdivision. Capitalizing on the consistency of functional parcellations, we defined robust functional maps at different levels of partitions, which are openly available for the scientific community. Our functional maps demonstrated a head–body and tail partition, subdivided along the anterior–posterior and medial–lateral axis. Behavioral profiling of these fine partitions based on activation data indicated an emotion–cognition gradient along the anterior–posterior axis and additionally suggested a self-world-centric gradient supporting the role of the hippocampus in the construction of abstract representations for spatial navigation and episodic memory.

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“…Though prior literature contends that the hippocampus may be particularly vulnerable to anoxia 3 , we did not identify preferential ABI in the hippocampus. However, it possible that these clinical diffusion weighted scans, which poorly discriminate mesial temporal structures 48 , had insufficient resolution to fully assess hippocampal ABI.…”

Section: Discussionmentioning

confidence: 99%

Regional distribution of anoxic brain injury after cardiac arrest: clinical and electrographic correlates

Fischer

et al. 2021

Preprint

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Introduction Disorders of consciousness, EEG background suppression and epileptic seizures are associated with poor outcome after cardiac arrest. The underlying patterns of anoxic brain injury associated with each remain unknown. Our objective was to identify the distribution of anoxic brain injury after cardiac arrest, as measured with diffusion MRI, and to define the regional correlates of disorders of consciousness, EEG background suppression, and seizures. Methods We analyzed patients from a prospectively-maintained, single-center database of unresponsive patients who underwent diffusion-weighted MRI following cardiac arrest (n = 204). We classified each patient based on recovery of consciousness (command-following) before discharge, the most continuous EEG background (burst suppression versus continuous), and the presence or absence of seizures. Anoxic brain injury was measured using the apparent diffusion coefficient (ADC) signal. We identified abnormalities in ADC relative to control subjects without cardiac arrest (n = 48) and used voxel lesion symptom mapping to identify regional associations with disorders of consciousness, EEG background suppression, and seizures. We then used a bootstrapped lasso regression procedure to identify robust, multivariate regional associations with each clinical and EEG variable. Finally, using area under receiver operating characteristic curves, we then compared the classification ability of the strongest regional associations to that of brain-wide summary measures. Results Compared to control subjects, cardiac arrest patients demonstrated a reduction in the ADC signal that was most significant in the occipital lobes. Disorders of consciousness were associated with reduced ADC most prominently in the occipital lobes, but also in the basal ganglia, medial thalamus and cerebellar nuclei. Regional injury more accurately classified patients with disorders of consciousness than whole-brain injury. Background suppression mapped to a similar set of brain regions, but regional injury could no better classify patients than whole-brain measures. Seizures were less common in patients with more severe anoxic injury, particularly in those with injury to the lateral temporal white matter. Discussion Anoxic brain injury was most prevalent in posterior cerebral regions, and this regional pattern of injury was a better predictor of disorders of consciousness than whole-brain injury measures. EEG background suppression lacked a specific regional association, but patients with injury to the temporal lobe were less likely to have seizures. Collectively, our results suggest that the regional pattern of anoxic brain injury is relevant to the clinical and electrographic sequelae of cardiac arrest and may hold importance for prognosis.

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High resolution in-vivo diffusion imaging of the human hippocampus

Cited by 29 publications

References 44 publications

Regional Distribution of Brain Injury After Cardiac Arrest

Regional Distribution of Brain Injury After Cardiac Arrest

Multimodal Parcellations and Extensive Behavioral Profiling Tackling the Hippocampus Gradient

Regional distribution of anoxic brain injury after cardiac arrest: clinical and electrographic correlates

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