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Evaluation of wave delivery methodology for brain MRE: Insights from computational simulations
Author(s) -
McGrath Deirdre M.,
Ravikumar Nishant,
Beltrachini Leandro,
Wilkinson Iain D.,
Frangi Alejandro F.,
Taylor Zeike A.
Publication year - 2017
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26333
Subject(s) - magnetic resonance elastography , isotropy , displacement (psychology) , computer science , viscoelasticity , acoustics , physics , elastography , ultrasound , psychology , optics , psychotherapist , thermodynamics
Purpose MR elastography (MRE) of the brain is being explored as a biomarker of neurodegenerative disease such as dementia. However, MRE measures for healthy brain have varied widely. Differing wave delivery methodologies may have influenced this, hence finite element‐based simulations were performed to explore this possibility. Methods The natural frequencies of a series of cranial models were calculated, and MRE‐associated vibration was simulated for different wave delivery methods at varying frequency, using simple isotropic viscoelastic material models for the brain. Displacement fields and the corresponding brain constitutive properties estimated by standard inversion techniques were compared across delivery methods and frequencies. Results The delivery methods produced widely different MRE displacement fields and inversions. Furthermore, resonances at natural frequencies influenced the displacement patterns. Consequently, some delivery methods led to lower inversion errors than others, and the error on the storage modulus varied by up to 11% between methods. Conclusion Wave delivery has a considerable impact on brain MRE reliability. Assuming small variations in brain biomechanics, as recently reported to accompany neurodegenerative disease (e.g., 7% for Alzheimer's disease), the effect of wave delivery is important. Hence, a consensus should be established on a consistent methodology to ensure diagnostic and prognostic consistency. Magn Reson Med 78:341–356, 2017. © 2016 International Society for Magnetic Resonance in Medicine