title: The first week after concussion: Blood flow, brain function and white matter microstructure.
abstract: Concussion is a major health concern, associated with short-term deficits in physical function, emotion and cognition, along with negative long-term health outcomes. However, we remain in the early stages of characterizing MRI markers of concussion, particularly during the first week post-injury when symptoms are most severe. In this study, 52 varsity athletes were scanned using Magnetic Resonance Imaging (MRI), including 26 athletes with acute concussion (scanned 1-7 days post-injury) and 26 matched control athletes. A comprehensive set of functional and structural MRI measures were analyzed, including cerebral blood flow (CBF) and global functional connectivity (Gconn) of grey matter, along with fractional anisotropy (FA) and mean diffusivity (MD) of white matter. An analysis comparing acutely concussed athletes and controls showed limited evidence for reliable mean effects of acute concussion, with only MD showing spatially extensive differences between groups. We subsequently demonstrated that the number of days post-injury explained a significant proportion of inter-subject variability in MRI markers of acutely concussed athletes. Athletes scanned at early acute injury (1-3 days) had elevated CBF and Gconn and reduced FA, but those scanned at late acute injury (5-7 days) had the opposite response. In contrast, MD showed a more complex, spatially-dependent relationship with days post-injury. These novel findings highlight the variability of MRI markers during the acute phase of concussion and the critical importance of considering the acute injury time interval, which has significant implications for studies relating acute MRI data to concussion outcomes.
authors.affiliation: The Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1M8, Canada.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Churchill
authors.affiliation: The Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1M8, Canada; Faculty of Kinesiology and Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON M5S 2W6, Canada.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hutchison
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON M5S 2W6, Canada.
authors.forename: Doug
authors.initials: D
authors.lastname: Richards
authors.affiliation: The Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1M8, Canada; Department of Medical Imaging, University of Toronto, Keenan Research Centre of the Li Ka Shing Knowledge Institute at St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1M8, Canada.
authors.forename: General
authors.initials: G
authors.lastname: Leung
authors.affiliation: Department of Medical Biophysics, University of Toronto, Sunnybrook Hospital, 2075 Bayview Ave., Toronto, ON M4N 3M5, Canada; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Graham
authors.affiliation: The Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, 209 Victoria Street, Toronto, ON M5B 1M8, Canada; Faculty of Medicine (Neurosurgery), University of Toronto, Toronto, Ontario, Canada; Institute of Biomaterals and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Tom A
authors.initials: TA
authors.lastname: Schweizer
mesh_terms: D000293:Adolescent; D016880:Anisotropy; D001265:Athletic Injuries / Q000150:complications; D001921:Brain / Q000473:pathology*; D001924:Brain Concussion / Q000000981:diagnostic imaging* / Q000209:etiology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D056324:Diffusion Tensor Imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D012720:Severity of Illness Index; D066127:White Matter / Q000000981:diagnostic imaging*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Cerebral blood flow; Concussion; Diffusion tensor imaging; Functional MRI; MRI