MRI properties of a unique hypo-intense layer in degraded articular cartilage.
To investigate the characteristics of a hypo-intense laminar appearance in articular cartilage under external loading, microscopic magnetic resonance imaging (μMRI) T1, T2 and T1ρ experiments of a total of 15 specimens of healthy and trypsin-degraded cartilage were performed at different soaking solutions (saline and 100 mM phosphate buffered saline (PBS)). T2 and T1ρ images of the healthy tissue in saline showed no load-induced laminar appearance, while a hypo-intense layer was clearly visible in the deep part of the degraded tissue at the magic angle. A significant difference was found between T2 values at 0° and 55° (from 16.5  ±  2.8 ms to 20.2  ±  2.7 ms, p  =  0.0005), and at 0° and 90° (16.5  ±  2.8 ms to 21.3  ±  2.6 ms, p  <  0.0001) in saline solution. In contrast, this hypo-intense laminar appearance largely disappeared when tissue was soaked in PBS. The visualization of this hypo-intensity appearance in different soaking mediums calls for caution in interpreting the data of relaxation times, chemical exchange and collagen fiber deformation.
Department of Physics and Center for Biomedical Research, Oakland University, Rochester, MI 48309, USA.
Nian
N
Wang
Farid
F
Badar
Yang
Y
Xia
D000818:Animals; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000737:chemistry*; D004285:Dogs; D008279:Magnetic Resonance Imaging / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*