The past decade has seen tremendous growth in efforts to establish noninvasive assessments of articular cartilage, motivated by a need to evaluate the efficacy of therapeutic interventions and to understand disease progression. The main tool in this regard is magnetic resonance imaging (MRI), which has emerged as the preferred means of imaging cartilage anatomy, and underlies the developing methods for imaging cartilage biochemical properties. Though anatomy and biochemistry of cartilage are undeniably important metrics, the sine qua non of cartilage functional integrity is its mechanical properties. The hypothesis to be examined in this proposal is that a spatial map computed from a combination MRI-derived biochemical metrics will correspond to spatially-localized mechanical properties. Preliminary studies using three human tibial plateau samples showed a strong correlation between a spatial map of GAG concentration (measured by MRI) and a corresponding map of mechanical stiffness (measured by indentation studies), suggesting the potential for MRI to provide a noninvasive measure of the cartilage mechanical properties. To build on these exciting preliminary data we aim to: 1. Evaluate whether the correlation between GAG and arthroscopic-probe indentation behavior is sustained as sample number is increased and whether the correlation is improved by considering an additional an MRI measure (T2) known to be influenced by collagen. 2. Evaluate the three regimes of mechanical behavior to see whether they have the same dependency on the biochemically-based MR metrics. The proposed studies represent an essential and new step towards functional imaging of cartilage. Importantly, the relatively new MR methodologies that reflect tissue biochemical properties provide the enabling technology that opens up this avenue of research. The spatially-localized information provided here would be potentially valuable in a myriad of contexts ranging from aiding our basic understanding of the macromolecular mechanism conferring cartilage stiffness, to the practical clinical question of identifying whether tissue is functionally competent.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR049204-04
Application #
7115753
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Program Officer
Lester, Gayle E
Project Start
2003-07-15
Project End
2008-06-30
Budget Start
2006-07-01
Budget End
2008-06-30
Support Year
4
Fiscal Year
2006
Total Cost
$246,932
Indirect Cost
Name
Beth Israel Deaconess Medical Center
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02215
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Baldassarri, Marta; Goodwin, Jesse S Little; Farley, Michelle L et al. (2007) Relationship between cartilage stiffness and dGEMRIC index: correlation and prediction. J Orthop Res 25:904-12
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Samosky, Joseph T; Burstein, Deborah; Eric Grimson, W et al. (2005) Spatially-localized correlation of dGEMRIC-measured GAG distribution and mechanical stiffness in the human tibial plateau. J Orthop Res 23:93-101