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Gd‐DTPA 2− as a measure of cartilage degradation
Author(s) -
Bashir Adil,
Gray Martha L.,
Burstein Deborah
Publication year - 1996
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.1910360504
Subject(s) - cartilage , chemistry , glycosaminoglycan , magnetization transfer , nuclear magnetic resonance , proton , magnetic resonance imaging , biochemistry , anatomy , physics , medicine , radiology , quantum mechanics
Glycosaminoglycans (GAGs) are the main source of tissue fixed charge density (FCD) in cartilage, and are lost early in arthritic diseases. We tested the hypothesis that, like Na + , the charged contrast agent Gd‐DTPA 2‐ (and hence proton T 1 ) could be used to measure tissue FCD and hence GAG concentration. NMR spectroscopy studies of cartilage explants demonstrated that there was a strong correlation ( r > 0.96) between proton T 1 in the presence of Gd‐DTPA 2‐ and tissue sodium and GAG concentrations. An ideal one‐compartment electrochemical (Donnan) equilibrium model was examined as a means of quantifying FCD from Gd‐DTPA 2‐ concentration, yielding a value 50% less but linearly correlated with the validated method of quantifying FCD from Na + . These data could be used as the basis of an empirical model with which to quantify FCD from Gd‐DTPA 2‐ concentration, or a more sophisticated physical model could be developed. Spatial distributions of FCD were easily observed in T 1 ‐weighted MRI studies of trypsin and interleukin‐1 induced cartilage degradation, with good histological correlation. Therefore, equilibration of the tissue in Gd‐DTPA 2‐ gives us the opportunity to directly image (through T 1 , weighting) the concentration of GAG, a major and critically important macromolecule in cartilage. Pilot clinical studies demonstrated Gd‐DTPA 2‐ penetration into cartilage, suggesting that this technique is clinically feasible.