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Characterization of the dynamic shear properties of hyaline cartilage using high‐frequency dynamic MR elastography
Author(s) -
Lopez Orlando,
Amrami Kimberly K.,
Manduca Armando,
Ehman Richard L.
Publication year - 2008
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.21474
Subject(s) - viscoelasticity , cartilage , collagenase , materials science , shear (geology) , biomedical engineering , hyaline cartilage , elastography , chemistry , articular cartilage , composite material , anatomy , acoustics , osteoarthritis , pathology , ultrasound , enzyme , medicine , biochemistry , alternative medicine , physics
This work evaluated the feasibility of dynamic MR Elastography (MRE) to quantify structural changes in bovine hyaline cartilage induced by selective enzymatic degradation. The ability of the technique to quantify the frequency‐dependent response of normal cartilage to shear in the kilohertz range was also explored. Bovine cartilage plugs of 8 mm in diameter were used for this study. The shear stiffness (μ s ) of each cartilage plug was measured before and after 16 hr of enzymatic treatments by dynamic MRE at 5000 Hz of shear excitation. Collagenase and trypsin were used to selectively affect the collagen and proteoglycans contents of the matrix. Additionally, normal cartilage plugs were tested by dynamic MRE at shear‐excitations of 3000–7000 Hz. Measured μ s of cartilage plugs showed a significant decrease (−37%, P < 0.05) after collagenase treatment and a significant decrease (−28%, P < 0.05) after trypsin treatment. Furthermore, a near‐linear increase (R 2 = 0.9141) in the speed of shear wave propagation with shear‐excitation frequency was observed in cartilage, indicating that wave speed is dominated by viscoelastic effects. These experiments suggest that dynamic MRE can provide a sensitive quantitative tool to characterize the degradation process and viscoelastic behavior of cartilage. Magn Reson Med 59:356–364, 2008. © 2008 Wiley‐Liss, Inc.