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Correlation of T 1ρ with fixed charge density in cartilage
Author(s) -
Wheaton Andrew J.,
Casey Francis L.,
Gougoutas Alexander J.,
Dodge George R.,
Borthakur Arijitt,
Lonner Jess H.,
Schumacher H. Ralph,
Reddy Ravinder
Publication year - 2004
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.20148
Subject(s) - osteoarthritis , cartilage , proteoglycan , correlation , linear regression , histology , chemistry , pathology , nuclear medicine , nuclear magnetic resonance , biomedical engineering , anatomy , biology , medicine , mathematics , physics , statistics , alternative medicine , geometry
Purpose To establish the specificity of T 1ρ with respect to fixed charge density (FCD) as a measure of proteoglycan (PG) content in cartilage during the onset of osteoarthritis (OA). Materials and Methods T 1ρ ‐weighted and sodium MRI were performed on cartilage samples of enzymatically degraded bovine explants and natural osteoarthritic human samples representing controlled and physiological models of OA, respectively. Spatial maps of T 1ρ and FCD (measured using the previously validated method of sodium MRI) were calculated from image data. Data were extracted from the maps and subjected to linear regression to compare changes in T 1ρ with changes in FCD in each model. Tissue samples were subjected to histological staining for a reduction in PG content. Results Plots of normalized T 1ρ rate vs. FCD were found to be strongly correlated (R 2 > 0.75 and 0.85) in both models with nearly the same slope of ≈1/2 ( P > 0.51). Loss of PG in bovine and human tissue was confirmed by histology. Conclusion The strong correlation of the FCD and T 1ρ data in both the controlled and physiological models demonstrates that changes in T 1ρ are due predominantly to changes in PG content. This work is a first step in establishing T 1ρ as a method of quantifying PG changes in early‐stage OA. J. Magn. Reson. Imaging 2004;20:519–525. © 2004 Wiley‐Liss, Inc.