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Conference Paper: Anisotropic viscoelastic properties of the corpus callosum - Application of high-resolution 3D MR-elastography to an Alzheimer mouse model

TitleAnisotropic viscoelastic properties of the corpus callosum - Application of high-resolution 3D MR-elastography to an Alzheimer mouse model
Authors
KeywordsAlzheimer's Disease
Anisotropy
Corpus Callosum
Demyelination
Magnetic Resonance Elastography
Viscoelastic Properties
White Matter
Issue Date2007
Citation
Proceedings - Ieee Ultrasonics Symposium, 2007, p. 676-679 How to Cite?
AbstractAlzheimer's disease (AD) is characterized by progressive cognitive deterioration together with declining activities of daily living and neuropsychiatric symptoms. It is the most common cause of dementia. It is recognized that the production and maintenance of myelin is essential for normal brain function. Aging-related breakdown of myelin negatively impacts the cognitive performances with the neurofibrilary tangles and amyloid plaques being the hallmarks of the disease. Nowadays, the only definite way to diagnose AD is to find out whether there are plaques and tangles in brain tissue. This requires histopathological examination of brain tissue. Previous researches on AD using MRI mainly focus on direct plaque imaging. This study aims to validate the hypothesis that AD alters the mechanical properties of the axons in the region between hippocampus and cortex, i.e. within the Corpus Callosum (CC) which is an area strongly affected by demvelination. As a unique tool to study non-invasively those properties, we use 3D MR-elastography operating at 1000Hz mechanical excitation frequency. Post-processing of the complex-valued displacement field provides the local fiber direction (determined by two Euler angles) and two complex shear moduli: one perpendicular to the local fiber direction and one parallel to it. Each modulus is a complex number giving access to both the anisotropic elasticity μ and viscosity η. The displacement fields are measured at an isotropic resolution of 300μm. Four transgenic female mice expressing mutant human APP/PS1 genes and three wild-type (WT) control mice were studied over several weeks. We observe locally enhanced elasticity and viscosity in the corpus callosum compared to the rest of the brain. As expected from normal anatomy, this region also shows a significantly higher anisotropy (μ ∥- μ ⊥ characterizing the transversal isotropic mechanical properties of this white matter region. The AD group shows a decrease in both μ ∥ and μ ⊥. It also seems to have a decreased value of perpendicular viscosity suggesting easier wave propagation in the transverse direction due to demyelination. Those preliminary results indicate that AD alters the mechanical properties of the white matter. Those differences were not detectable when utilizing an isotropic model for the reconstruction of the viscoelastic properties. © 2007 IEEE.
Persistent Identifierhttp://hdl.handle.net/10722/155481
ISSN
References

 

DC FieldValueLanguage
dc.contributor.authorLarrat, Ben_US
dc.contributor.authorChan, QCen_US
dc.contributor.authorYang, XFen_US
dc.contributor.authorLi, Gen_US
dc.contributor.authorYang, ESen_US
dc.contributor.authorFink, Men_US
dc.contributor.authorSinkus, Ren_US
dc.date.accessioned2012-08-08T08:33:43Z-
dc.date.available2012-08-08T08:33:43Z-
dc.date.issued2007en_US
dc.identifier.citationProceedings - Ieee Ultrasonics Symposium, 2007, p. 676-679en_US
dc.identifier.issn1051-0117en_US
dc.identifier.urihttp://hdl.handle.net/10722/155481-
dc.description.abstractAlzheimer's disease (AD) is characterized by progressive cognitive deterioration together with declining activities of daily living and neuropsychiatric symptoms. It is the most common cause of dementia. It is recognized that the production and maintenance of myelin is essential for normal brain function. Aging-related breakdown of myelin negatively impacts the cognitive performances with the neurofibrilary tangles and amyloid plaques being the hallmarks of the disease. Nowadays, the only definite way to diagnose AD is to find out whether there are plaques and tangles in brain tissue. This requires histopathological examination of brain tissue. Previous researches on AD using MRI mainly focus on direct plaque imaging. This study aims to validate the hypothesis that AD alters the mechanical properties of the axons in the region between hippocampus and cortex, i.e. within the Corpus Callosum (CC) which is an area strongly affected by demvelination. As a unique tool to study non-invasively those properties, we use 3D MR-elastography operating at 1000Hz mechanical excitation frequency. Post-processing of the complex-valued displacement field provides the local fiber direction (determined by two Euler angles) and two complex shear moduli: one perpendicular to the local fiber direction and one parallel to it. Each modulus is a complex number giving access to both the anisotropic elasticity μ and viscosity η. The displacement fields are measured at an isotropic resolution of 300μm. Four transgenic female mice expressing mutant human APP/PS1 genes and three wild-type (WT) control mice were studied over several weeks. We observe locally enhanced elasticity and viscosity in the corpus callosum compared to the rest of the brain. As expected from normal anatomy, this region also shows a significantly higher anisotropy (μ ∥- μ ⊥ characterizing the transversal isotropic mechanical properties of this white matter region. The AD group shows a decrease in both μ ∥ and μ ⊥. It also seems to have a decreased value of perpendicular viscosity suggesting easier wave propagation in the transverse direction due to demyelination. Those preliminary results indicate that AD alters the mechanical properties of the white matter. Those differences were not detectable when utilizing an isotropic model for the reconstruction of the viscoelastic properties. © 2007 IEEE.en_US
dc.languageengen_US
dc.relation.ispartofProceedings - IEEE Ultrasonics Symposiumen_US
dc.subjectAlzheimer's Diseaseen_US
dc.subjectAnisotropyen_US
dc.subjectCorpus Callosumen_US
dc.subjectDemyelinationen_US
dc.subjectMagnetic Resonance Elastographyen_US
dc.subjectViscoelastic Propertiesen_US
dc.subjectWhite Matteren_US
dc.titleAnisotropic viscoelastic properties of the corpus callosum - Application of high-resolution 3D MR-elastography to an Alzheimer mouse modelen_US
dc.typeConference_Paperen_US
dc.identifier.emailYang, ES:esyang@hkueee.hku.hken_US
dc.identifier.authorityYang, ES=rp00199en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1109/ULTSYM.2007.175en_US
dc.identifier.scopuseid_2-s2.0-48149094552en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-48149094552&selection=ref&src=s&origin=recordpageen_US
dc.identifier.spage676en_US
dc.identifier.epage679en_US
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridLarrat, B=24479283000en_US
dc.identifier.scopusauthoridChan, QC=6602497305en_US
dc.identifier.scopusauthoridYang, XF=23007172600en_US
dc.identifier.scopusauthoridLi, G=7407054189en_US
dc.identifier.scopusauthoridYang, ES=7202021229en_US
dc.identifier.scopusauthoridFink, M=7402450445en_US
dc.identifier.scopusauthoridSinkus, R=6701740519en_US

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