title: Stability of white matter changes related to Huntington's disease in the presence of imaging noise: a DTI study.
abstract: Movement artifacts and other sources of noise are a matter of concern particularly in the neuroimaging research of movement disorders such as Huntington's disease (HD). Using diffusion weighted imaging (DWI) and fractional anisotropy (FA) as a compound marker of white matter integrity, we investigated the effect of movement on HD specific changes in magnetic resonance imaging (MRI) data and how post hoc compensation for it affects the MRI results. To this end, we studied by 3T MRI: 18 early affected, 22 premanifest gene-positive subjects, 23 healthy controls (50 slices of 2.3 mm thickness per volume, 64 diffusion-weighted directions (b = 1000 s/mm2), 8 minimal diffusion-weighting (b = 100 s/mm2)); and by 1.5 T imaging: 29 premanifest HD, 30 controls (40 axial slices of 2.3 mm thickness per volume, 61 diffusion-weighted directions (b = 1000 s/mm2), minimal diffusion-weighting (b = 100 s/mm2)). An outlier based method was developed to identify movement and other sources of noise by comparing the index DWI direction against a weighted average computed from all other directions of the same subject. No significant differences were observed when separately comparing each group of patients with and without removal of DWI volumes that contained artifacts. In line with previous DWI-based studies, decreased FA in the corpus callosum and increased FA around the basal ganglia were observed when premanifest mutation carriers and early affected patients were compared with healthy controls. These findings demonstrate the robustness of the FA value in the presence of movement and thus encourage multi-center imaging studies in HD.
authors.affiliation: Dept. of Neurology, University of Ulm, Ulm, Germany; Freiburg Brain Imaging, Department of Neurology, University Freiburg Medical Center, Germany; Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, UK; Department of Neuroradiology, University Medical Center Freiburg, Germany; Department of Neurodegenerative Disease, UCL Institute of Neurology, London, UK and Freiburg Brain Imaging, Department of Psychiatry and Psychotherapy. University of Freiburg.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Müller
authors.forename: Volkmar
authors.initials: V
authors.lastname: Glauche
authors.forename: Marianne J U
authors.initials: MJ
authors.lastname: Novak
authors.forename: Thao
authors.initials: T
authors.lastname: Nguyen-Thanh
authors.forename: Alexander
authors.initials: A
authors.lastname: Unrath
authors.forename: Nayana
authors.initials: N
authors.lastname: Lahiri
authors.forename: Joy
authors.initials: J
authors.lastname: Read
authors.forename: Miranda Julia
authors.initials: MJ
authors.lastname: Say
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Tabrizi
authors.forename: Jan
authors.initials: J
authors.lastname: Kassubek
authors.forename: Stefan
authors.initials: S
authors.lastname: Kloppel