Goodwin D W, Zhu H, Dunn J F
Department of Radiology, Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Lebanon, NH 03756, USA.
AJR Am J Roentgenol. 2000 Feb;174(2):405-9. doi: 10.2214/ajr.174.2.1740405.
Our goal was to determine how the three-dimensional structure of hyaline cartilage affects its MR appearance and to correlate this appearance with detailed structural analysis using scanning electron microscopy and freeze-fracture sectioning techniques.
In vitro 7-T spin-echo MR images of hyaline cartilage specimens from four patients undergoing above-knee amputations were obtained parallel and perpendicular to the main magnetic field. Specimens were imaged with low- and high-power scanning electron microscopy after freeze fracturing. The corresponding images from both techniques were analyzed with specific attention to the three-dimensional structure of the cartilage, collagen fibril orientation, and respective changes in the MR appearance.
Freeze fracturing of cartilage reveals a curved fracture plane. Expected changes in signal intensity predicted by the magic angle effect correlated with observed changes in signal intensity across the thickness of the sample. Changes in individual collagen fibril orientation did not correspond to MR layering.
The three-dimensional organization of collagen in cartilage has a strong influence on the MR appearance of cartilage. This influence is caused by the restriction of water mobility and the resulting magic angle effect caused by curvature of the collagen network, possibly because of the influence on proteoglycan orientation.
我们的目标是确定透明软骨的三维结构如何影响其磁共振成像表现，并将这种表现与使用扫描电子显微镜和冷冻断裂切片技术进行的详细结构分析相关联。
对4例接受膝上截肢手术患者的透明软骨标本进行体外7-T自旋回波磁共振成像，成像方向平行和垂直于主磁场。标本在冷冻断裂后用低倍和高倍扫描电子显微镜成像。对两种技术的相应图像进行分析，特别关注软骨的三维结构、胶原纤维方向以及磁共振成像表现的相应变化。
软骨的冷冻断裂显示出一个弯曲的断裂平面。由魔角效应预测的信号强度预期变化与样品厚度方向上观察到的信号强度变化相关。单个胶原纤维方向的变化与磁共振分层不对应。
软骨中胶原的三维组织结构对软骨的磁共振成像表现有很大影响。这种影响是由胶原网络曲率导致的水流动性受限以及由此产生的魔角效应引起的，可能是由于对蛋白聚糖方向的影响。
