Brain microstructural alterations in COVID-19: a systematic review of diffusion weighted imaging studies

Following its emergence in Wuhan, COVID-19 has been associated with neurological sequalae, pathophysiological basis of which has been under investigation from the early reports. Herein, we aim to provide a comprehensive overview on white matter microstructural findings in COVID-19 patents. We performed a systematic literature search on PubMed, Scopus, Web of Science, and EMBASE databases on February 9th, 2025, using the combination of keywords related to COVID-19, DTI, and NODDI. Study selection and data extraction was performed to provide a qualitative synthesis of the data. Mean diffusivity (MD) and fractional anisotropy (FA) were the most reported diffusion parameters. Significant alterations in diffusion parameters of longitudinal fasciculi, thalamic radiations, corpus callosum (CC), fronto-occipital fasciculus (FOF), cortico-spinal tract (CST) and uncinate fasciculi (UF) were repeatedly reported among in the studies, of which the results on changes in CR and LF were almost consistent. The observed changes in white matter microstructural integrity are associated with the psychiatric and cognitive symptoms in post-COVID-19 phase. This observation warrants long-term follow-up of COVID-19 patients for the potential neurological sequalae of this disease.