Department of Diagnostic and Interventional Radiology Leipzig University Hospital Liebigstrasse 20 Leipzig Germany.
Magn Reson Med. 2013 Jul;70(1):225-31. doi: 10.1002/mrm.24795. Epub 2013 May 28.
To demonstrate the feasibility of a novel experimental method to quantitatively analyze fiber-network deformation in compressed cartilage by angle-sensitive magnetic resonance imaging (MRI) of cartilage.
Three knee cartilage samples of an adult sheep were imaged in a high-resolution MRI scanner at 7 T. Main fiber orientation and its "offset" from the direction perpendicular to the bone-cartilage boundary were derived from MR images taken at different orientations with respect to B0. Bending of the collagen fibers was determined from weight-bearing MRI with the load (up to 1.0 MPa) applied over the whole sample surface. A "fascicle" model of the cartilage ultrastructure was assumed to analyze characteristic intensity variations in T2-weighted images under load.
T2-weighted MR images showed a strong variation of the signal intensities with sample orientation. In the T2-weighted weight-bearing series, regions of high signal intensity underwent shifts from the lateral to the central parts in all three cartilage samples. The bending of the collagen fibers was determined to be 27.2°, 35.4°, and 40.0° per MPa, respectively.
Assuming a "fascicle" model, the presented MRI method provides quantitative measures of structural adjustments in compressed cartilage. Our preliminary analysis suggests that cartilage fiber deformation includes both bending and crimping.
通过对软骨进行角度敏感磁共振成像（MRI）来定量分析压缩软骨中纤维网络变形，展示一种新型实验方法的可行性。
在 7T 高分辨率 MRI 扫描仪中对三只成年绵羊的膝关节软骨样本进行成像。从相对于 B0 的不同方向采集的 MR 图像中得出主要纤维方向及其与骨软骨边界垂直方向的“偏移”。通过在整个样本表面施加高达 1.0MPa 的负载来确定胶原纤维的弯曲。假设软骨超微结构的“束”模型来分析负载下 T2 加权图像中的特征强度变化。
T2 加权 MR 图像显示信号强度随样本方向的强烈变化。在 T2 加权承重系列中，所有三个软骨样本中高信号强度区域从外侧向中央部分发生了移位。分别确定胶原纤维的弯曲角度为 27.2°、35.4°和 40.0°/MPa。
在假设“束”模型的情况下，本研究提出的 MRI 方法提供了压缩软骨结构调整的定量测量。我们的初步分析表明，软骨纤维变形包括弯曲和卷曲。
