Premium
A compact 0.5 T MR elastography device and its application for studying viscoelasticity changes in biological tissues during progressive formalin fixation
Author(s) -
Braun Jürgen,
Tzschätzsch Heiko,
Körting Clara,
Ariza de Schellenberger Angela,
Jenderka Marika,
Drießle Toni,
Ledwig Michael,
Sack Ingolf
Publication year - 2018
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.26659
Subject(s) - magnetic resonance elastography , viscoelasticity , elastography , materials science , fixation (population genetics) , biomedical engineering , nuclear magnetic resonance , shear modulus , magnetic resonance imaging , soft tissue , chemistry , composite material , pathology , medicine , physics , acoustics , ultrasound , radiology , biochemistry , gene
Purpose To develop a method of compact tabletop magnetic resonance elastography (MRE) for rheological tests of tissue samples and to measure changes in viscoelastic powerlaw constants of liver and brain tissue during progressive fixation. Methods A 10‐mm bore, 0.5‐T permanent‐magnet–based MRI system was equipped with a gradient‐amplifier–controlled piezo‐actuator and motion‐sensitive spin echo sequence for inducing and measuring harmonic shear vibrations in cylindrical samples. Shear modulus dispersion functions were acquired at 200–5700 Hz in animal tissues at different states of formalin fixation and fitted by the springpot powerlaw model to obtain shear modulus μ and powerlaw exponent α . Results In a frequency range of 300–1500 Hz, unfixed liver tissue was softer and less dispersive than brain tissue with μ = 1.68 ± 0.17 kPa and α = 0.51 ± 0.06 versus μ = 2.60 ± 0.68 kPa and α = 0.68 ± 0.03. Twenty‐eight hours of formalin fixation yielded a 400‐fold increase in liver μ , 25‐fold increase in brain μ , and two‐fold reduction in α of both tissues. Conclusion Compact 0.5‐T MRE facilitates automated measurement of shear modulus dispersion in biological tissue at low costs. Formalin fixation changes the viscoelastic properties of tissues from viscous‐soft to elastic‐stiff more markedly in liver than brain. Magn Reson Med 79:470–478, 2018. © 2017 International Society for Magnetic Resonance in Medicine.