Machine learning to investigate superficial white matter integrity in early multiple sclerosis
Korhan Buyukturkoglu, Christopher Vergara, Valentina Fuentealba, Ceren Tozlu, Jacob B. Dahan, Britta Carroll, Amy Kuceyeski, Claire Riley, James Sumowski, Carlos Oliva, Ranganatha Sitaram, Pamela Guevara, Victoria M. Leavitt
Abstract
Abstract Background and Purpose This study aims todetermine the sensitivity of superficial white matter (SWM) integrity as a metric to distinguish early multiple sclerosis (MS) patients from healthy controls (HC). Methods Fractional anisotropy and mean diffusivity (MD) values from SWM bundles across the cortex and major deep white matter (DWM) tracts were extracted from 29 early MS patients and 31 age‐ and sex‐matched HC. Thickness of 68 cortical regions and resting‐state functional‐connectivity (RSFC) among them were calculated. The distribution of structural and functional metrics between groups were compared using Wilcoxon rank‐sum test. Utilizing a machine learning method (adaptive boosting), 6 models were built based on: 1‐SWM, 2‐DWM, 3‐SWM and DWM, 4‐cortical thickness, or 5‐RSFC measures. In model 6, all features from previous models were incorporated. The models were trained with nested 5‐folds cross‐validation. Area under the receiver operating characteristic curve (AUC roc ) values were calculated to evaluate classification performance of each model. Permutation tests were used to compare the AUC roc values. Results Patients had higher MD in SWM bundles including insula, inferior frontal, orbitofrontal, superior and medial temporal, and pre‐ and post‐central cortices ( p < .05). No group differences were found for any other MRI metric. The model incorporating SWM and DWM features provided the best classification (AUC roc = 0.75). The SWM model provided higher AUC roc (0.74), compared to DWM (0.63), cortical thickness (0.67), RSFC (0.63), and all‐features (0.68) models ( p < .001 for all). Conclusion Our results reveal a non‐random pattern of SWM abnormalities at early stages of MS even before pronounced structural and functional alterations emerge.