Predicting Future Brain Tissue Loss From White Matter Connectivity Disruption in Ischemic Stroke

BACKGROUND AND PURPOSE: The Network Modification (NeMo) Tool uses a library of brain connectivity maps from normal subjects to quantify the amount of structural connectivity loss caused by focal brain lesions. We hypothesized that the NeMo Tool could predict remote brain tissue loss caused by post-stroke loss of connectivity. METHODS: Baseline and follow-up MRIs (10.7±7.5 months apart) from 26 patients with acute ischemic stroke (age 74.6±14.1 years, initial NIH Stroke Scale 3.1±3.1) were collected. Lesion masks derived from diffusion-weighted images were superimposed on the NeMo Tool’s connectivity maps, and regional structural connectivity losses were estimated via the Change in Connectivity (ChaCo) score (i.e., the percent of tracks connecting to a given region that pass through the lesion mask). ChaCo scores were correlated with subsequent atrophy. RESULTS: Stroke lesions’ size and location varied, but they were more frequent in the left hemisphere. ChaCo scores, generally higher in regions near stroke lesions, reflected this lateralization and heterogeneity. ChaCo scores were highest in the postcentral and precentral gyri, insula, middle cingulate, thalami, putamen, caudate nuclei, and pallidum. Moderate, significant partial correlations were found between baseline ChaCo scores and measures of subsequent tissue loss (r=0.43, p=4.6×10(−9); r=0.61, p=1.4×10(−18)), correcting for the time between scans. CONCLUSIONS: ChaCo scores varied, but the most affected regions included those with sensorimotor, perception, learning and memory functions. Correlations between baseline ChaCo and subsequent tissue loss suggest that the NeMo Tool could be used to identify regions most susceptible to remote degeneration from acute infarcts