title: A prospective microstructure imaging study in mixed-martial artists using geometric measures and diffusion tensor imaging: methods and findings.
abstract: Although diffusion magnetic resonance imaging (dMRI) has been widely used to characterize the effects of repetitive mild traumatic brain injury (rmTBI), to date no studies have investigated how novel geometric models of microstructure relate to more typical diffusion tensor imaging (DTI) sequences. Moreover, few studies have evaluated the sensitivity of different registration pipelines (non-linear, linear and tract-based spatial statistics) for detecting dMRI abnormalities in clinical populations. Results from single-subject analyses in healthy controls (HC) indicated a strong negative relationship between fractional anisotropy (FA) and orientation dispersion index (ODI) in both white and gray matter. Equally important, only moderate relationships existed between all other estimates of free/intracellular water volume fractions and more traditional DTI metrics (FA, mean, axial and radial diffusivity). These findings suggest that geometric measures provide differential information about the cellular microstructure relative to traditional DTI measures. Results also suggest greater sensitivity for non-linear registration pipelines that maximize the anatomical information available in T1-weighted images. Clinically, rmTBI resulted in a pattern of decreased FA and increased ODI, largely overlapping in space, in conjunction with increased intracellular and free water fractions, highlighting the potential role of edema following repeated head trauma. In summary, current results suggest that geometric models of diffusion can provide relatively unique information regarding potential mechanisms of pathology that contribute to long-term neurological damage.
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA. amayer@mrn.org.|Neurology and Psychiatry Departments, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA. amayer@mrn.org.|Department of Psychology, University of New Mexico, Albuquerque, NM, 87131, USA. amayer@mrn.org.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Mayer
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA.
authors.forename: Josef M
authors.initials: JM
authors.lastname: Ling
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Dodd
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA.|Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Meier
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA.
authors.forename: Faith M
authors.initials: FM
authors.lastname: Hanlon
authors.affiliation: The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, 87106, USA.
authors.forename: Stefan D
authors.initials: SD
authors.lastname: Klimaj
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging*; D001929:Brain Edema / Q000000981:diagnostic imaging / Q000209:etiology; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000209:etiology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D016139:Martial Arts / Q000293:injuries*; D009483:Neuropsychological Tests; D011446:Prospective Studies; D012044:Regression Analysis; D012189:Retrospective Studies; D057566:Self Report; D066127:White Matter / Q000000981:diagnostic imaging
keywords: Concussion; Diffusion tensor imaging; Edema; NODDI; Repetitive injury; Water fractions