The role of relaxation times in monitoring proteoglycan depletion in articular cartilage

Abstract

Various proton relaxation times (T2, T1ρ, and gadolinium‐diethylene triamine pentaacetic acid [Gd‐DTPA]‐enhanced T1) were measured in articular cartilage in vitro at 3 T to assess their role in visualizing proteoglycan depletion. Cartilage‐bone specimens were obtained from patients who underwent total joint replacement and got a double dose of Gd‐DTPA 2 hours prior surgery. In these specimens, regions of mechanically undamaged cartilage having a decreased content of proteoglycans showed about 15% lower T1 values compared with apparently normal cartilaginous tissue. The expected increase of the T2 relaxation time was not observed in these regions. On the other hand, the T2 and, to a lower degree, T1 relaxation times were found to be increased in regions of cartilage fibrillation. The T1ρ relaxation times obtained were slightly longer than the corresponding T2 values, but both parameters showed almost identical spatial distributions. J. Magn. Reson. Imaging 1999;10:497–502. © 1999 Wiley‐Liss, Inc.

Current knowledge and importance of dGEMRIC techniques in diagnosis of hip joint diseases

“…Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is sensitive to the charge density of cartilage that is contributed to by the negatively charged GAG chains [4][5][6][7][8][9][10][11]. Because the GAG content decreases early over the course of cartilage degeneration, the dGEMRIC technique looks promising for the development of new diagnostic and therapeutic procedures.…”

T1rho, T2 and focal knee cartilage abnormalities in physically active and sedentary healthy subjects versus early OA patients—a 3.0-Tesla MRI study

“…It reflects the ability of free water proton molecules to move and to exchange energy. The estimation of cartilage T2 relaxation times is sensitive to a wide range of water interactions in tissue including macromolecular concentration [14][15][16][17], structure of the macromolecules [18], and bulk organization of the extracellular matrix [19]. In particular, it therefore also depends on the content, orientation, and anisotropy of collagen [20,21].…”

Structural evaluation of articular cartilage: Potential contribution of magnetic resonance techniques used in clinical practice

“…AU ϭ arbitrary units; SB ϭ subchondral bone; SZ ϭ superficial zone; RZ ϭ radial zone. (6,7,37), as have the impact of collagen fibril orientation and the related anisotropism (8)(9)(10). Previous studies have led to controversial conclusions regarding correlations among the imaging pattern and the histologic and biochemical cartilage structure (11)(12)(13)(14)(15).…”

“…As reported by other investigators (7,10,12), the cartilage area with high signal intensity corresponded to high GAG:Col ratios. This relationship was not found in the cartilage of the 3-year-old animal, since the MR intensity profiles actually demonstrated a decrease in the MR signal from the surface to the interior, while we measured an increase in the GAG:Col ratio with depth.…”

“…The T2-weighted sequences, which depict the cartilage with a rather heterogeneous pattern, are considered to be more informative regarding the structure of the cartilage. The physical support of the MR images is complex, and many investigators have attempted to define the factors that will influence the MR signal and how they will influence it (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The exploration of human cartilage is difficult, since only cadaveric specimens or osteoarthritic specimens obtained from surgery can be studied for histologic and biochemical correlations.…”