Free water improves detection of changes in the substantia nigra in parkinsonism: A multisite study

Edward Ofori, Florian Krismer, Roxana G. Burciu, Ofer Pasternak, Johanna L. McCracken, Mechelle M. Lewis, Guangwei Du, Nikolaus R. McFarland, Michael S. Okun, Werner Poewe, Christoph Mueller, Elke R. Gizewski, Michael Schocke, Christian Kremser, Hong Li, Xuemei Huang, Klaus Seppi, David E. Vaillancourt

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Background: Imaging markers that are sensitive to parkinsonism across multiple sites are critically needed for clinical trials. The objective of this study was to evaluate changes in the substantia nigra using single- and bi-tensor models of diffusion magnetic resonance imaging in PD, MSA, and PSP. Methods: The study cohort (n = 425) included 107 healthy controls and 184 PD, 63 MSA, and 71 PSP patients from 3 movement disorder centers. Bi-tensor free water, free-water-corrected fractional anisotropy, free-water-corrected mean diffusivity, single-tensor fractional anisotropy, and single-tensor mean diffusivity were computed for the anterior and posterior substantia nigra. Correlations were computed between diffusion MRI measures and clinical measures. Results: In the posterior substantia nigra, free water was greater for PSP than MSA and PD patients and controls. PD and MSA both had greater free water than controls. Free-water-corrected fractional anisotropy values were greater for PSP patents than for controls and PD patients. PSP and MSA patient single-tensor mean diffusivity values were greater than controls, and single-tensor fractional anisotropy values were lower for PSP patients than for healthy controls. The parkinsonism effect size for free water was 0.145 in the posterior substantia nigra and 0.072 for single-tensor mean diffusivity. The direction of correlations between single-tensor mean diffusivity and free-water values and clinical scores was similar at each site. Conclusions: Free-water values in the posterior substantia nigra provide a consistent pattern of findings across patients with PD, MSA, and PSP in a large cohort across 3 sites. Free water in the posterior substantia nigra relates to clinical measures of motor and cognitive symptoms in a large cohort of parkinsonism.

Original languageEnglish (US)
Pages (from-to)1457-1464
Number of pages8
JournalMovement Disorders
Volume32
Issue number10
DOIs
StatePublished - Oct 2017

Keywords

  • cell
  • diffusion imaging
  • dopamine
  • midbrain
  • substantia nigra

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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