Correlation between biochemical composition and magnetic resonance appearance of articular cartilage (original) (raw)
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Arthritis & Rheumatism, 2001
Methods. The cartilage of 3-month-old, 3-yearold, and 13-year-old animals was studied. T1-and T2-weighted MR sequences were performed using a 1.5T clinical imager and a 3-inch surface coil. Histologic slices (5 m) of cartilage specimens were stained with picrosirius red (for collagen) and toluidine blue (for glycosaminoglycans [GAGs]). A polarized light study was performed to determine the collagen network organization. Except for the 13-year-old animal cartilage, the biochemical content was studied on slices cut parallel to the surface to determine GAG and hydroxyproline (collagen) content. Cartilage profiles were performed to determine the MR pixel intensity and the histologic color intensity.
Proteoglycan and collagen sensitive MRI evaluation of normal and degenerated articular cartilage
Journal of Orthopaedic Research, 2004
Quantitative magnetic resonance imaging (MRI) techniques have earlier been developed to characterize the structure and composition of articular cartilage. Particularly, Gd-DTPA'-enhanced T, imaging is sensitive to cartilage proteoglycan content, while T, relaxation time mapping is indicative of the integrity and arrangement of the collagen network. However, the ability of these techniques to detect early osteoarthrotic changes in cartilage has not been demonstrated. In this study, normal and spontaneously degenerated bovine patellar cartilage samples (n = 32) were investigated in vitro using the aforementioned techniques. For reference, mechanical, histological and biochemical properties of the adjacent tissue were determined, and a grading system, the cartilage quality index (CQI), was used to score the structural and functional integrity of each sample. As cartilage degeneration progressed, a statistically significant increase in the superficial T2 (y. = 0.494, p < 0.05) and a decrease in superficial and bulk TI in the presence of Gd-DTPA'-(v =-0.681 and-0.688 (p < 0.05), respectively) were observed. Gd-DTPA'-enhanced TI imaging served as the best predictor of tissue integrity and accounted for about 50% of the variation in CQI. The present results reveal that changes in the quantitative MRI parameters studied are indicative of structural and compositional alterations as well as the mechanical impairment of spontaneously degenerated articular cartilage.
The morphology of articular cartilage assessed by magnetic resonance imaging (MRI)
Surgical and Radiologic Anatomy, 1994
Quantitative assessment of cartilage volume and thickness in a formalin-alcohol fixed specimen of a human patella was conducted with magnetic resonance imaging (MRI), as it is still unclear whether the morphology of normal and damaged cartilage can be accurately demonstrated with this technique. MR imaging was carried out at 1.0 T (section thickness 2 mm, in-plane-resolution 0.39-0.58 mm) with the following pulse sequences: 1) T1-weighted spin-echo, 2) 3D-MPRAGE, 3) 3D-FISP, 4) 3D-MTC-FISP, 5) 3D-DESS, 6) 3D-FLASH. Following imaging, the patella was sectioned perpendicular to the articular surface at intervals of 2 mm with a diamond band-saw. The volume of its cartilage was determined from the anatomical sections and the MR images, using a Vidas IPS 10 image analysing system (Kontron). Measurements were carried out with and without the low-signal layer in the transitional zone between the articular cartilage and the subchondral bone. If the low-signal layer was included, the volume was overestimated with MRI by 16 to 19%. Without the low-signal layer the volumes were less than those determined from the anatomical sections: T1-SE-18.2%, MPRAGE -22.6%, FISP -17.1%, MTC-FISP -9.5%, DESS -9.3% and FLASH -6.1%. The coefficient of variation for a 6-fold determination of the volume amounted to between 6.2% (T1-SE) and 2.6% (FLASH). The FLASH sequence allowed the most valid and reproducible assessment of the cartilage morphology. The remaining difference from the real volume of the cartilage may be due to the fact that the calcified zone of the cartilage is not delineated by MRI.
Investigation of laminar appearance of articular cartilage by means of magnetic resonance microscopy
Magnetic Resonance Imaging, 1996
Magnetic resonance (MR) images and relaxation and diffusion maps of articular cartilage were obtained to explain discrepancies in its MR appearance. Porcine specimens were studied only by MR microscopy. For human specimens a combination of MR microscopy and large-scale MR imaging was used. Common features in the laminar structures of human and porcine samples are described. It was found that the decay of transverse magnetization was nonexponential with a rapidly decaying component which prevented construction of reliable proton-density maps. Dependence of T2 values on the orientation of specimens in the magnetic field as well as magnetization transfer experiments supported the previous suggestions about a significant role of dipolar interaction with protons of collagen in the laminar appearance of articular cartilage. The loss of the laminar structure induced by rotation of the human cartilage specimen around the axis normal to its surface demonstrated nonuniform angular distribution of the collagen fibers within the layer.
MR imaging of articular cartilage physiology
Magnetic resonance imaging clinics of North America, 2011
The newer magnetic resonance (MR) imaging methods can give insights into the initiation, progression, and eventual treatment of osteoarthritis. Sodium imaging is specific for changes in proteoglycan (PG) content without the need for an exogenous contrast agent. T1ρ imaging is sensitive to early PG depletion. Delayed gadolinium-enhanced MR imaging has high resolution and sensitivity. T2 mapping is straightforward and is sensitive to changes in collagen and water content. Ultrashort echo time MR imaging examines the osteochondral junction. Magnetization transfer provides improved contrast between cartilage and fluid. Diffusion-weighted imaging may be a valuable tool in postoperative imaging.
Effect of collagen cross-linking on quantitative MRI parameters of articular cartilage
Osteoarthritis and Cartilage, 2016
Objective: To investigate the sensitivity of quantitative magnetic resonance imaging (MRI) parameters to increase of collagen cross-linking in articular cartilage, a factor possibly contributing to the aging-related development of osteoarthritis (OA). The issue has not been widely studied although collagen cross-links may significantly affect the evaluation of cartilage imaging outcome. Design: Osteochondral samples (n ¼ 14) were prepared from seven bovine patellae. To induce crosslinking, seven samples were incubated in threose while the other seven served as non-treated controls. The specimens were scanned at 9.4 T for T 1 , T 1Gd (dGEMRIC), T 2 , adiabatic and continuous wave (CW) T 1r , adiabatic T 2r and T 1sat relaxation times. Specimens from adjacent tissue were identically treated and used for reference to determine biomechanical properties, collagen, proteoglycan and crosslink contents, fixed charge density (FCD), collagen fibril anisotropy and water concentration of cartilage. Results: In the threose-treated sample group, cross-links (pentosidine, lysyl pyridinoline (LP)), FCD and equilibrium modulus were significantly (P < 0.05) higher as compared to the non-treated group. Threose treatment resulted in significantly greater T 1Gd relaxation time constant (þ26%, P < 0.05), although proteoglycan content was not altered. Adiabatic and CWT 1r were also significantly increased (þ16%, þ28%, P < 0.05) while pre-contrast T 1 was significantly decreased (À10%, P < 0.05) in the threose group. T 2 , T 2r and T 1sat did not change significantly. Conclusion: Threose treatment induced collagen cross-linking and changes in the properties of articular cartilage, which were detected by T 1 , T 1Gd and T 1r relaxation time constants. Cross-linking should be considered especially when interpreting the outcome of contrast-enhanced MRI in aging populations.
Proteoglycan Depletion and Magnetic Resonance Parameters of Articular Cartilage
Archives of Biochemistry and Biophysics, 2001
Calcium ions and various amounts of proteoglycans were removed from porcine articular cartilage explants using ethylenediaminetetraacetic acid or guanidinium chloride solutions. The water proton magnetic parameters such as T 1 and T 2 relaxation times, diffusion (D), and magnetization transfer (M S / M 0 ) were then measured by 1D MR microscopy on native specimens, after incubation in the extracting solutions and after final reconditioning in a physiological saline. While the replacement of the interstitial fluid by the treating solutions strongly affected the various MR parameters, calcium depletion did not show any influence on the MRI appearance of the chondral tissue. Interestingly, only the longitudinal relaxation time T 1 and the diffusion coefficient D were seen to be sensitive to an extensive proteoglycan depletion of the tissue. Our results indicate that a modest proteoglycan depletion, as it occurs in the early stage of a pathological cartilage degradation, has little relevance to the above MR parameters. Further MRI studies on the macromolecular components of cartilage are, therefore, necessary for a better understanding of the interaction mechanisms between water and extracellular matrix that might lead to the early diagnosis of the cartilage damage.
Imaging of articular cartilage: current concepts
Joints, 2014
Magnetic resonance imaging (MRI) is the gold standard method for non-invasive assessment of joint cartilage, providing information on the structure, morphology and molecular composition of this tissue. There are certain minimum requirements for a MRI study of cartilage tissue: machines with a high magnetic field (> 1.5 Tesla); the use of surface coils; and the use of T2-weighted, proton density-weighted fast-spin echo (T2 FSE-DP) and 3D fat-suppressed T1-weighted gradient echo (3D-FS T1W GRE) sequences. For better contrast between the different joint structures, MR arthography is a method that can highlight minimal fibrillation or fractures of the articular surface and allow evaluation of the integrity of the native cartilagerepair tissue interface. To assess the biochemical composition of cartilage and cartilage repair tissue, various techniques have been proposed for studying proteoglycans [dGEMRIC, T1rho mapping, sodium (23Na) imaging MRI, etc.], collagen, and water distributi...
Osteoarthritis and Cartilage, 2007
Background: Magnetic resonance imaging (MRI) is one of the most potential methods for non-invasive diagnosis of cartilage disorders. Several methods have been established for clinical use; T 1 relaxation time imaging with negatively charged contrast agent (delayed gadolinium enhanced MRI of cartilage, dGEMRIC) has been shown to be sensitive to proteoglycan (PG) content while T 2 relaxation time has been demonstrated to express properties of the collagen fibril network. The use of native T 1 relaxation time has received less attention. Objective: In the present study, magnetic resonance (MR) parameters of different types of patellar cartilage were studied with respect to the mechanical properties of the tissue. The general usefulness of the parameters to predict mechanical properties was investigated using cartilage from different species and stages of maturation. Methods: dGEMRIC, T 2 and native T 1 relaxation times of healthy mature human, juvenile porcine and juvenile bovine articular cartilage samples were measured at 9.4 T at 25 C. Mechanical properties (Young's modulus and dynamic modulus) of the samples were measured in unconfined compression using a material testing device. The relationships between MRI and mechanical parameters and potential differences between different types of tissues were tested statistically. Results: Significant, but varying relationships were established between T 1 or T 2 relaxation time and mechanical properties, depending on tissue type. The values of mechanical parameters were in line with the results previously reported in the literature. Unexpectedly, dGEMRIC showed no statistically significant association with the mechanical properties. Variation in the assumption of native T 1 value did not induce significant differences in the calculated contrast agent concentration, and consequently did not affect prediction of mechanical properties. Conclusion: For patellae, a complex variation in the relationships between T 2 and mechanical properties in different groups was revealed. The results support the conclusion that juvenile animal tissue, exhibiting a highly complex collagenous architecture, may not always serve as a realistic model for mature human tissue with a typical three-zone network organization, and other than bulk metrics are required for the analysis of cartilage T 2. As the multilayered collagen network can strongly control the mechanical characteristics of juvenile tissue, it may mask the mechanical role of PGs and explain why dGEMRIC could not predict mechanical parameters in patellar cartilage.