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Acad Radiol. 2002 Dec;9(12):1388-94.

Proteoglycan depletion-induced changes in transverse relaxation maps of cartilage: comparison of T2 and T1rho.

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MMRRCC, Department of Radiology, B1, Stellar-Chance Laboratories, University of Pennsylvania Medical Center, 422 Curie Blvd, Philadelphia, PA 19104-6100, USA.



The authors performed this study to (a) measure changes in T2 relaxation rates, signal-to-noise ratio (SNR), and contrast with sequential depletion of proteoglycan in cartilage; (b) determine whether there is a relationship between the T2 relaxation rate and proteoglycan in cartilage; and (c) compare the T2 mapping method with the spin-lattice relaxation time in the rotating frame (T1rho) mapping method in the quantification of proteoglycan-induced changes.


T2- and T1rho-weighted magnetic resonance (MR) images were obtained in five bovine patellae. All images were obtained with a 4-T whole-body MR unit and a 10-cm-diameter transmit-receive quadrature birdcage coil tuned to 170 MHz. T2 and T1rho maps were computed.


The SNR and contrast on the T2-weighted images were, on average, about 43% lower than those on the corresponding T1rho-weighted images. The T2 relaxation rates varied randomly without any particular trend, which yielded a poor correlation with sequential depletion of proteoglycan (R2 = 0.008, P < .70). There was excellent linear correlation between the percentage of proteoglycan in the tissue and the T1rho relaxation rate (R2 = 0.85, P < .0001).


T2-weighted imaging neither yields quantitative information about the changes in proteoglycan distribution in cartilage nor can be used for longitudinal studies to quantify proteoglycan-induced changes. T1rho-weighted imaging, however, is sensitive to sequential depletion of proteoglycan in bovine cartilage and can be used to quantify proteoglycan-induced changes.

[Indexed for MEDLINE]

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