Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China.
J Xray Sci Technol. 2012;20(4):437-46. doi: 10.3233/XST-2012-00350.
In order to evaluate the capacity of T1ρ-MRI(Magnetic Resonance Imaging) technique in distinguishing a four-layered zonal structure of articular cartilage for detecting the early-onset osteoarthritis (OA), eight 3-month-old female Danish landrace pigs, weighing 45.3 ± 5.5 kg, were used in this study. Two hind knees were randomly divided into two groups. IL-1β was injected into articular cavities in one group while physiological saline into another as a control one. Six hours later, the patellae were obtained for T1ρ-MRI and histological examination to distinguish the four-layered zonal structure of articular cartilages. The thickness of each layer and their percentages in the entire cartilage were measured on both T1ρ-MR images and the histological slices. T1ρ values of every layer were calculated from T1ρ-mapping images. In the result, the four-layered zonal structure of articular cartilage was displayed on both T1ρ-MR images and the histological slices. The ICC between these two methods was 0.981 for single measures (P=0.001), and 0.990 for average measures (P = 0.001). Compared with control patellae, T1ρ values significantly increased on the superficial and calcified layers in the IL-1β treated patellae (P=0.037). Therefore, this study demonstrates that the four-layered zonal structure of the articular cartilage is visibly displayed on the T1ρ-MR images. T1ρ-MRI technique can detect the earliest event of cartilage degeneration while these measurable changes are not shown in the histological slices. It is possible to use this technique for observing the effects of early interventions on the early-onset OA.
为了评估 T1ρ-MRI（磁共振成像）技术在区分关节软骨四层分区结构以检测早期骨关节炎（OA）中的能力，本研究使用了 8 只 3 月龄雌性丹麦兰德瑞斯猪，体重为 45.3±5.5kg。将每只猪的双侧后膝关节随机分为两组。一组膝关节腔注射白细胞介素 1β（IL-1β），另一组注射生理盐水作为对照。6 小时后，取髌骨进行 T1ρ-MRI 和组织学检查，以区分关节软骨的四层分区结构。在 T1ρ-MR 图像和组织切片上测量各层的厚度及其在整个软骨中的百分比。从 T1ρ 映射图像计算各层的 T1ρ 值。结果显示，T1ρ-MR 图像和组织切片上均显示出关节软骨的四层分区结构。两种方法的单测一致性 ICC 为 0.981（P=0.001），平均一致性 ICC 为 0.990（P=0.001）。与对照组髌骨相比，IL-1β 处理的髌骨的浅层和钙化层的 T1ρ 值显著增加（P=0.037）。因此，本研究表明，关节软骨的四层分区结构在 T1ρ-MR 图像上清晰可见。T1ρ-MRI 技术可以检测到软骨退变的最早事件，而这些可测量的变化在组织切片上并不明显。因此，该技术可能用于观察早期干预对早期 OA 的影响。
