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Non‐invasive measurement of brain viscoelasticity using magnetic resonance elastography
Author(s) -
Sack Ingolf,
Beierbach Bernd,
Hamhaber Uwe,
Klatt Dieter,
Braun Jürgen
Publication year - 2008
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1189
Subject(s) - magnetic resonance elastography , viscoelasticity , elastography , shear modulus , materials science , reproducibility , nuclear magnetic resonance , biomedical engineering , magnetic resonance imaging , medicine , ultrasound , composite material , chemistry , physics , radiology , chromatography
The purpose of this work was to develop magnetic resonance elastography (MRE) for the fast and reproducible measurement of spatially averaged viscoelastic constants of living human brain. The technique was based on a phase‐sensitive echo planar imaging acquisition. Motion encoding was orthogonal to the image plane and synchronized to intracranial shear vibrations at driving frequencies of 25 and 50 Hz induced by a head‐rocker actuator. Ten time‐resolved phase‐difference wave images were recorded within 60 s and analyzed for shear stiffness and shear viscosity. Six healthy volunteers (six men; mean age 34.5 years; age range 25–44 years) underwent 23–39 follow‐up MRE studies over a period of 6 months. Interindividual mean ± SD shear moduli and shear viscosities were found to be 1.17 ± 0.03 kPa and 3.1 ± 0.4 Pas for 25 Hz and 1.56 ± 0.07 kPa and 3.4 ± 0.2 Pas for 50 Hz, respectively ( P ≤ 0.01). The intraindividual range of shear modulus data was 1.01–1.31 kPa (25 Hz) and 1.33–1.77 kPa (50 Hz). The observed modulus dispersion indicates a limited applicability of Voigt's model to explain viscoelastic behavior of brain parenchyma within the applied frequency range. The narrow distribution of data within small confidence intervals demonstrates excellent reproducibility of the experimental protocol. The results are necessary as reference data for future comparisons between healthy and pathological human brain viscoelastic data. Copyright © 2007 John Wiley & Sons, Ltd.