Marshall K W, Mikulis D J, Guthrie B M
Division of Orthopaedics, Toronto Hospital, Ontario, Canada.
J Orthop Res. 1995 Nov;13(6):814-23. doi: 10.1002/jor.1100130603.
A quadrature knee coil was used in conjunction with a magnetic resonance imaging scanner for quantitation of test phantom volumes, ex vivo bovine cartilage thickness, and in vivo human articular cartilage volumes. Optimal magnetic resonance parameters were obtained by testing a series of spin-echo and gradient-echo pulse sequences to determine the sequence that provided the highest resolution of articular cartilage and best defined the cartilage interfaces with synovial fluid and subchondral bone. Extensive testing revealed that two sequences were required to define articular cartilage accurately: a spoiled gradient-echo sequence and a steady state free-precession sequence. Three-dimensional reconstruction and statistical analyses of test phantoms and of bovine and human cartilage images were performed. Differences between actual phantom volumes and three-dimensional measurements demonstrated that, as magnetic resonance slice thickness was increased, the measurement variability also increased (coefficient of variation ranging from 1.7 +/- 1.3% for 1.0 mm slice thickness to 22.7 +/- 1.9% for 3.0 mm slice thickness). When the phantom volume was greater than 1,800 mm3, the intraobserver, interobserver and interscan accuracies were greater than 97, 98, and 96%, respectively. This high degree of reproducibility pertained for the data on in vivo human cartilage data also. For experienced observers, the intraobserver and interobserver reproducibility were greater than 98 and 97%, respectively. The interscan reproducibility was greater than 98%. These data demonstrate that improved magnetic resonance pulse sequencing, in conjunction with three-dimensional reconstruction and measurement techniques, can accurately and reproducibly measure the volume of articular cartilage. Clinical application of this approach offers the potential for early diagnosis of osteoarthritis and for serial, noninvasive assessment of changes in articular cartilage volume in response to therapeutic modalities.
使用正交膝关节线圈与磁共振成像扫描仪相结合，用于定量检测测试体模体积、离体牛软骨厚度以及体内人体关节软骨体积。通过测试一系列自旋回波和梯度回波脉冲序列，以获得最佳磁共振参数，从而确定能提供最高关节软骨分辨率且能最佳界定软骨与滑液及软骨下骨界面的序列。广泛测试表明，需要两个序列才能准确界定关节软骨：一个扰相梯度回波序列和一个稳态自由进动序列。对测试体模以及牛和人体软骨图像进行了三维重建和统计分析。实际体模体积与三维测量值之间的差异表明，随着磁共振切片厚度增加，测量变异性也增加（变异系数范围从1.0毫米切片厚度时的1.7±1.3%到3.0毫米切片厚度时的22.7±1.9%）。当体模体积大于1800立方毫米时，观察者内、观察者间和扫描间的准确度分别大于97%、98%和96%。这种高度的可重复性也适用于体内人体软骨数据。对于有经验的观察者，观察者内和观察者间的可重复性分别大于98%和97%。扫描间的可重复性大于98%。这些数据表明，改进的磁共振脉冲序列与三维重建和测量技术相结合，能够准确且可重复地测量关节软骨体积。这种方法的临床应用为骨关节炎的早期诊断以及对关节软骨体积因治疗方式而发生的变化进行系列无创评估提供了可能性。
