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Mapping Cartilage Proteoglycans Ex-vivo using a Clinical MRI System

Friday, November 08, 2013 — Poster Session III

10:00 a.m. – 12:00 p.m.

FAES Academic Center (Upper-Level Terrace)




  • M Bouhrara
  • D.A. Reiter
  • H Celik
  • V Lukas
  • K.W. Fishbein
  • R.G. Spencer


Osteoarthritis (OA) is characterized in part by loss of proteoglycan molecules (PG), leading to impaired mechanical function. Magnetic resonance imaging (MRI) is becoming the leading imaging modality for characterization of OA; however, measures such as relaxation times provide only indirect assessment of macromolecular content. Recently, we have developed techniques for directly mapping PG in cartilage at high (9.4T) MRI field strength through use of multiexponential transverse relaxation analysis. We describe here advances which render this technique applicable to PG mapping in the clinical research setting. First, we have decreased image acquisition time through use of a multi-gradient echo pulse sequence, permitting acquisition of multiple image datasets simultaneously. Further, we have addressed the signal-to-noise limitations of clinical MR by incorporating Rician, as opposed to Gaussian, noise, properly accounting for the noise characteristics of conventional MR imaging. Computer simulations, and analysis of images of phantoms obtained on a 3T MRI system, demonstrated substantially improved accuracy and precision of this analysis. Substantial improvements were also achieved in results obtained on bovine cartilage in relatively short scan times. This work lays the foundation for mapping PG content in human subjects, with the goal of noninvasively quantifying macromolecular changes accompanying the development of OA.

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