title: Cerebral magnetic resonance elastography in supranuclear palsy and idiopathic Parkinson's disease.
abstract: Detection and discrimination of neurodegenerative Parkinson syndromes are challenging clinical tasks and the use of standard T1- and T2-weighted cerebral magnetic resonance (MR) imaging is limited to exclude symptomatic Parkinsonism. We used a quantitative structural MR-based technique, MR-elastography (MRE), to assess viscoelastic properties of the brain, providing insights into altered tissue architecture in neurodegenerative diseases on a macroscopic level. We measured single-slice multifrequency MRE (MMRE) and three-dimensional MRE (3DMRE) in two neurodegenerative disorders with overlapping clinical presentation but different neuropathology - progressive supranuclear palsy (PSP: N = 16) and idiopathic Parkinson's disease (PD: N = 18) as well as in controls (N = 18). In PSP, both MMRE (Δμ = - 28.8%, Δα = - 4.9%) and 3DMRE (Δ|G*|: - 10.6%, Δφ: - 34.6%) were significantly reduced compared to controls, with a pronounced reduction within the lentiform nucleus (Δμ = - 34.6%, Δα = - 8.1%; Δ|G*|: - 7.8%, Δφ: - 44.8%). MRE in PD showed a comparable pattern, but overall reduction in brain elasticity was less severe reaching significance only in the lentiform nucleus (Δμ n.s., Δα = - 7.4%; Δ|G*|: - 6.9%, Δφ: n.s.). Beyond that, patients showed a close negative correlation between MRE constants and clinical severity. Our data indicate that brain viscoelasticity in PSP and PD is differently affected by the underlying neurodegeneration; whereas in PSP all MRE constants are reduced and changes in brain softness (reduced μ and |G*|) predominate those of viscosity (α and φ) in PD.
authors.affiliation: Department of Neurology, Charité - University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Lipp
authors.forename: Radmila
authors.initials: R
authors.lastname: Trbojevic
authors.forename: Friedemann
authors.initials: F
authors.lastname: Paul
authors.forename: Andreas
authors.initials: A
authors.lastname: Fehlner
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hirsch
authors.forename: Michael
authors.initials: M
authors.lastname: Scheel
authors.forename: Cornelia
authors.initials: C
authors.lastname: Noack
authors.forename: Jürgen
authors.initials: J
authors.lastname: Braun
authors.forename: Ingolf
authors.initials: I
authors.lastname: Sack
keywords: Elasticity; MR-elastography; MRE; Parkinson disease; Progressive supranuclear palsy; Viscosity