title: Diffusion MRI-based cortical complexity alterations associated with executive function in multiple sclerosis.
abstract: OBJECTIVE
  To report a novel magnetic resonance imaging measure (diffusion orientational complexity [DOC]) in a study of people with multiple sclerosis (MS) and healthy controls and to determine patterns of abnormality, correlations with conventional diffusion measures, and associations with cognitive function.
  
  
  METHODS
  We performed high angular resolution diffusion imaging (HARDI) and measured DOC, mean diffusivity (MD), and fractional anisotropy (FA) in 51 MS patients and 28 healthy controls. All subjects had a 2-mm isotropic HARDI scan on a 3 T scanner using a 32-channel head receiver coil. DOC, MD, and FA were measured in three regions of interest (ROIs) in frontal cortex linked to executive function, two ROIs in occipital cortex thought unlikely to affect cognition, and in the whole cortex.
  
  
  RESULTS
  Frontal cortex DOC was significantly decreased in MS patients. DOC correlated mostly with FA but not MD in controls and with MD but not FA in people with MS. In regression models that included all three diffusion-based measures, frontal cortex DOC and frontal cortex FA independently predicted executive function scores.
  
  
  CONCLUSIONS
  DOC is a new useful measure of functionally relevant cortical pathology in MS, providing information that complements conventional diffusion measures.
authors.affiliation: NMR Unit, Department of Neuroinflammation, UCL Institute of Neurology, London, UK. n.muhlert@ucl.ac.uk
authors.forename: Nils
authors.initials: N
authors.lastname: Muhlert
authors.forename: Varun
authors.initials: V
authors.lastname: Sethi
authors.forename: Torben
authors.initials: T
authors.lastname: Schneider
authors.forename: Pankaj
authors.initials: P
authors.lastname: Daga
authors.forename: Lisa
authors.initials: L
authors.lastname: Cipolotti
authors.forename: Hamied A
authors.initials: HA
authors.lastname: Haroon
authors.forename: Geoff J M
authors.initials: GJ
authors.lastname: Parker
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ourselin
authors.forename: Claudia A M
authors.initials: CA
authors.lastname: Wheeler-Kingshott
authors.forename: David H
authors.initials: DH
authors.lastname: Miller
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ron
authors.forename: Declan T
authors.initials: DT
authors.lastname: Chard
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056344:Executive Function; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology*; D009473:Neuronal Plasticity; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity