New Techniques in Articular Cartilage Imaging

CORR Insights®: Corticosteroid Injections Give Small and Transient Pain Relief in Rotator Cuff Tendinosis: A Meta-analysis

“…More immediate evidence may be found in histological analysis or imaging analysis such as MRI, observing water content, or ultrastructure via specific spin sequences. Currently, there are no well-studied MRI spin sequences looking at tendon ultrastructure, but there are some for cartilage ultrastructure [3]. Ultrasound may also offer insights into in-vivo tendon ultrastructure.…”

The Application of Imaging in Osteoarthritis

“…T2 also exhibits a non-monoexponential behaviour of T2 in cartilage which can make quantification of proton density difficult and has a long acquisition time (Burstein, Gray et al 2009;Crema, Roemer et al 2011). Further preventable errors can result from variations in voxel size, parameter selection, signal-to-noise ratio and receiver coil between institutions (Potter, Black et al 2009). T1ρ measures the spin-lattice relaxation time in the rotating frame and is similar to T2 relaxation except that an additional radiofrequency pulse is applied after the magnetization is tipped into the transverse plane with an exponential relationship of signal decay to the time constant T1ρ (Burstein, Gray et al 2009).…”

“…Articular cartilage is primarily hyaline cartilage which exhibits 3D anisotropic characteristics (physical and biological properties are direction dependent). The matrix composition and organization vary according to the depth from the articular surface including a superficial zone, a transitional zone, a radial zone and a zone of calcified cartilage (Potter, Black et al 2009). Cartilage can be conceptualized as a biphasic model consisting of a solid phase (glycoproteins, collagen, proteoglycans and chondrocytes) and a fluid phase (water and ions) that comprises 75% of cartilage by weight (Peterfy and Genant 1996).…”

“…MRI imaging techniques such as dGEMRIC and Na imaging specifically quantify changes in GAG concentration by exploiting the correlation of change in ionic concentration with GAG concentration since proteoglycans have substantial negative fixed charge (Burstein, Bashir et al 2000;Xia, Zheng et al 2008;Potter, Black et al 2009;Crema, Roemer et al 2011). The dGEMRIC technique uses T1 mapping of an intravenously administered anionic contrast agent gadopentate dimeglumine (Gd-DTPA 2-) which allows quantitative assessment of GAG content.…”

“…The relaxation times of T1 and T2 are thus dependent on water content and indirectly the associated collagen network allowing imaging without contrast. T2 mapping is essentially the pixel by pixel solving of the T2 relaxation curve and can be used to delineate collagen composition of cartilage as well as menisci, ligaments and tendons by utilizing special pulsed sequences (ultrashort echo time techniques) (Potter, Black et al 2009). Early OA generates a more heterogenous T2 map than normal cartilage but should be interpreted with caution since T2 maps are affected by physical activity and there is no direct correlation between OA grade and T2 changes (Crema, Roemer et al 2011).…”