Department of Physics and Center for Biomedical Research, Oakland University, Rochester, Michigan, USA.
Microsc Res Tech. 2022 Apr;85(4):1483-1493. doi: 10.1002/jemt.24011. Epub 2021 Dec 3.
This dual-modality microscopic imaging study quantifies the interface region between the noncalcified cartilage and the subchondral bone plate, which includes the deep portion of the noncalcified articular cartilage and the zone of calcified cartilage (ZCC). This interface region is typically not visible in routine MRI but becomes visible in MRI with the application of an ultra-short echo time (UTE) sequence. A number of cartilage-bone blocks from a well-documented canine humeral head were harvested for imaging by microscopic MRI (μMRI) and PLM (polarized light microscopy). In μMRI, T2 anisotropic images were acquired by 2D gradient-echo, magnetization-prepared spin-echo and UTE sequences at the 0° and 55° (the magic angle) orientations at 11.7 μm/pixel resolution. In PLM, quantitative optical retardation (nm) and collagen orientation (°) were mapped from the thin sections from the same μMRI specimens at 0.5-2 μm pixel resolutions. The orientational and organizational architecture of the collagen matrix in this interface region was quantified and correlated between the complementary imaging. The magic angle effect as seen in the noncalcified cartilage was statistically confirmed in ZCC in μMRI, which was further supported by quantitative PLM. With an enhanced understanding of the tissue properties in this important interface region, it will potentially be possible to monitor the changes of this tissue region which is instrumental to the initiation and development of osteoarthritis and other joint diseases.
这项双模态微观成像研究定量了非钙化软骨与软骨下骨板之间的界面区域，其中包括非钙化关节软骨的深部和钙化软骨区（ZCC）。该界面区域在常规 MRI 中通常不可见，但在应用超短回波时间（UTE）序列的 MRI 中变得可见。从一个有充分记录的犬肱骨头上采集了多个软骨-骨块用于微观 MRI（μMRI）和偏光显微镜（PLM）成像。在 μMRI 中，通过二维梯度回波、磁化准备自旋回波和 UTE 序列以 0°和 55°（魔法角）方向在 11.7 μm/pixel 的分辨率下采集 T2 各向异性图像。在 PLM 中，从相同 μMRI 标本的薄片中以 0.5-2 μm 的像素分辨率映射出定量的光延迟（nm）和胶原取向（°）。在互补成像中对该界面区域的胶原基质的取向和组织架构进行了定量和相关性分析。在 μMRI 中，非钙化软骨中的“魔法角效应”在 ZCC 中得到了统计学证实，定量 PLM 进一步支持了这一效应。通过对这个重要界面区域的组织特性有了更深入的了解，就有可能监测该组织区域的变化，这对于骨关节炎和其他关节疾病的发生和发展至关重要。
