Jaremko Jacob L, Maciejewski Conrad M, Cheng Rita W T, Ronsky Janet L, Thompson Richard B, Lambert Robert G W, Dhillon Sukhvinder S
Department of Radiology and Diagnostic Imaging, Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada.
J Magn Reson Imaging. 2007 Oct;26(4):992-1000. doi: 10.1002/jmri.21107.
To quantify the accuracy of magnetic resonance imaging (MRI) measurement of change in cartilage volume due to thin linear excisions, simulating arthritic cartilage losses, by comparison with laboratory volume measurements in an ex vivo porcine model.
We scanned 15 porcine patellae by T1-weighted spoiled gradient echo (SPGR) MRI at baseline and after excision of up to three thin layers of articular cartilage. Excised fragment volume was determined from density and weight. Postexcision scans were "fused" to the baseline scan by three-dimensional (3D) registration. This allowed automated recalculation of the remaining cartilage volume within a baseline region of interest (ROI) following each excision. We compared MRI estimates of change in cartilage volume to direct laboratory measurement of fragment volume.
Our 38 excised fragments averaged 0.16 mL, or approximately 7% of cartilage volume. MRI and laboratory estimates of total cartilage volume loss differed by 1.6% +/- 13.2% (mean, coefficient of variation [CV]). Accuracy was +/-0.1 mL for 95% of scans.
MRI estimates of small changes in porcine patellar cartilage volume were unbiased, reliable, and accurate to 0.1 mL. Despite a proportionately high error in the very thin fragments tested, achievement of similar accuracy in vivo would be adequate to detect approximately two years of osteoarthritic cartilage loss.
通过与体外猪模型中的实验室体积测量结果进行比较，量化磁共振成像（MRI）测量因薄线性切除模拟关节炎软骨损失而导致的软骨体积变化的准确性。
我们在基线时以及切除多达三层关节软骨后，通过T1加权扰相梯度回波（SPGR）MRI对15个猪髌骨进行扫描。根据密度和重量确定切除碎片的体积。切除后的扫描通过三维（3D）配准与基线扫描“融合”。这允许在每次切除后自动重新计算基线感兴趣区域（ROI）内剩余的软骨体积。我们将MRI对软骨体积变化的估计与碎片体积的直接实验室测量结果进行比较。
我们的38个切除碎片平均为0.16 mL，约占软骨体积的7%。MRI和实验室对总软骨体积损失的估计相差1.6%±13.2%（平均值，变异系数[CV]）。95%的扫描准确性为±0.1 mL。
MRI对猪髌骨软骨体积微小变化的估计无偏差、可靠且精确至0.1 mL。尽管在所测试的非常薄的碎片中误差比例较高，但在体内达到类似的准确性足以检测约两年的骨关节炎软骨损失。
