Developments in dynamic MR elastography for in vitro biomechanical assessment of hyaline cartilage under high-frequency cyclical shear

Orlando Lopez, Kimberly K. Amrami, Armando Manduca, Phillip J. Rossman, Richard L. Ehman

Research output: Contribution to journalReview articlepeer-review

35 Scopus citations

Abstract

The design, construction, and evaluation of a customized dynamic magnetic resonance elastography (MRE) technique for biomechanical assessment of hyaline cartilage in vitro are described. For quantification of the dynamic shear properties of hyaline cartilage by dynamic MRE, mechanical excitation and motion sensitization were performed at frequencies in the kilohertz range. A custom electromechanical actuator and a z-axis gradient coil were used to generate and image shear waves throughout cartilage at 1000-10,000 Hz. A radiofrequency (RF) coil was also constructed for high-resolution imaging. The technique was validated at 4000 and 6000 Hz by quantifying differences in shear stiffness between soft (∼200 kPa) and stiff (∼300 kPa) layers of 5-mm-thick bilayered phantoms. The technique was then used to quantify the dynamic shear properties of bovine and shark hyaline cartilage samples at frequencies up to 9000 Hz. The results demonstrate that one can obtain high-resolution shear stiffness measurements of hyaline cartilage and small, stiff, multilayered phantoms at high frequencies by generating robust mechanical excitations and using large magnetic field gradients. Dynamic MRE can potentially be used to directly quantify the dynamic shear properties of hyaline and articular cartilage, as well as other cartilaginous materials and engineered constructs.

Original languageEnglish (US)
Pages (from-to)310-320
Number of pages11
JournalJournal of Magnetic Resonance Imaging
Volume25
Issue number2
DOIs
StatePublished - Feb 2007

Keywords

  • Articular cartilage
  • Dynamic shear properties
  • Hyaline cartilage
  • Magnetic resonance elastography
  • Shear stiffness
  • Tissue characterization

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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