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Cerebral magnetic resonance elastography in supranuclear palsy and idiopathic Parkinson's disease.

Lipp A, Trbojevic R, Paul F, Fehlner A, Hirsch S, Scheel M, Noack C, Braun J, Sack I - Neuroimage Clin (2013)

Bottom Line: 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.).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Charité - University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.

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.

No MeSH data available.


Related in: MedlinePlus

Normalised parameter maps obtained by 3DMRE. The grayscale in the /G*/ maps is from 0 to 3 kPa, the colorscale of phi is from 0 to 0.2. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)
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f0010: Normalised parameter maps obtained by 3DMRE. The grayscale in the /G*/ maps is from 0 to 3 kPa, the colorscale of phi is from 0 to 0.2. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)

Mentions: Contrary to MMRE, where Δμ > Δα, in 3DMRE Δ/G*/ < Δφ, i.e. the dimensionless phase-based parameter, displayed a higher disease-related change than the shear-modulus parameter, highlighting that the mechanical constants measured by MMRE and 3DMRE provide independent information on brain constitution. Although μ and φ display similarly high rates of change with disease, φ has a much higher intra-group variability and is thus less reliable than μ. The high variability of φ is also reflected in the normalised parameter maps shown in Fig. 2 for /G*/ and φ in a central slice of each of our groups. Fig. 2 addresses the local variation of 3DMRE parameters. Since φ reflects the duality of fluid–solid properties of tissue it is highly affected by the heterogeneous distribution of fluid-filled spaces in the brain. In contrast, /G*/ appears to be smoother in the normalised group maps with less in-plane variation than φ, which is consistent with the relative magnitude of the standard deviations given in Table 2. Both /G*/- and φ-image intensities decrease from the healthy state to PD and PSP. Again, pronounced signal deterioration is seen in the lentiform nucleus, which are demarcated by dashed red lines in the /G*/ maps in Fig. 2. Mean intensities and SD values in these regions are 1913 ± 196 Pa, 1757 ± 117 Pa, 1551 ± 140 Pa for controls, PD and PSP patients, respectively. From 2D-MMRE no normalised parameter maps were attainable. All group mean values and standard deviations are summarised in Table 2.


Cerebral magnetic resonance elastography in supranuclear palsy and idiopathic Parkinson's disease.

Lipp A, Trbojevic R, Paul F, Fehlner A, Hirsch S, Scheel M, Noack C, Braun J, Sack I - Neuroimage Clin (2013)

Normalised parameter maps obtained by 3DMRE. The grayscale in the /G*/ maps is from 0 to 3 kPa, the colorscale of phi is from 0 to 0.2. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3814959&req=5

f0010: Normalised parameter maps obtained by 3DMRE. The grayscale in the /G*/ maps is from 0 to 3 kPa, the colorscale of phi is from 0 to 0.2. (For interpretation of the references to colour in this figure, the reader is referred to the web version of this article.)
Mentions: Contrary to MMRE, where Δμ > Δα, in 3DMRE Δ/G*/ < Δφ, i.e. the dimensionless phase-based parameter, displayed a higher disease-related change than the shear-modulus parameter, highlighting that the mechanical constants measured by MMRE and 3DMRE provide independent information on brain constitution. Although μ and φ display similarly high rates of change with disease, φ has a much higher intra-group variability and is thus less reliable than μ. The high variability of φ is also reflected in the normalised parameter maps shown in Fig. 2 for /G*/ and φ in a central slice of each of our groups. Fig. 2 addresses the local variation of 3DMRE parameters. Since φ reflects the duality of fluid–solid properties of tissue it is highly affected by the heterogeneous distribution of fluid-filled spaces in the brain. In contrast, /G*/ appears to be smoother in the normalised group maps with less in-plane variation than φ, which is consistent with the relative magnitude of the standard deviations given in Table 2. Both /G*/- and φ-image intensities decrease from the healthy state to PD and PSP. Again, pronounced signal deterioration is seen in the lentiform nucleus, which are demarcated by dashed red lines in the /G*/ maps in Fig. 2. Mean intensities and SD values in these regions are 1913 ± 196 Pa, 1757 ± 117 Pa, 1551 ± 140 Pa for controls, PD and PSP patients, respectively. From 2D-MMRE no normalised parameter maps were attainable. All group mean values and standard deviations are summarised in Table 2.

Bottom Line: 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.).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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Charité - University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.

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.

No MeSH data available.


Related in: MedlinePlus