Quantifying brain health in acute ischemic stroke through effective reserve

Abstract

AbstractObjectiveTo evaluate brain health through the use of expanded structural measures of reserve, that incorporate pre-existing pathology and cerebrovascular disease burden.BackgroundOutcome modeling at the time of stroke is a key challenge in patient care. The related concepts of brain health and reserve may help to understand the observed differences in patient outcomes. Effective reserve (eR) quantifies the brain’s capacity to compensate for negative effects, while accounting for pre-existing disease burden. Here, we extend the concept of eR by including measures of white matter hyperintensity (WMH) burden and compare the utility of brain volume and brain parenchymal fraction (BPF) to enhance its modeling capabilities.Design/MethodsAcute ischemic stroke patients from a single center between 2003-2011 with available neuroimaging data were included in this study. Modified Rankin Score (mRS) at 90 days post admission was used to assess functional outcome. Neuroimaging data were analyzed using dedicated deep-learning enabled pipelines to extract measures of WMH, brain, and intracranial volumes (ICV). BPF is given as the ratio of brain volume to ICV. eR is defined as a latent variable using structural equation modeling that includes age, WMH volume, and either BPF or brain volume. Models were compared using Bayes Information Criterion (BIC).Results476 patients were eligible for inclusion: median age 65.8 (interquartile range: 55.3-76.3) years, 65.3% male. There was an inverse association between eR and mRS in both brain volume and BPF models (path coefficients: -0.75 and -0.55, respectively; p<0.001). The model utilizing brain volume (BIC=4429.6) outperformed the model using BPF (BIC=4802.2).ConclusionsIn this work, we significantly extended the concept of eR and advanced its translational potential. The demonstrated association of higher eR and better post-stroke outcome signifies its potential as a descriptor of brain health, and a protective measure against acute ischemic injury.