Non-invasive functional assessment and evaluation of treatment response in the articular cartilage using high-magnetic resonance imaging

为了研究对骨关节炎等关节疾病患者具有低侵入性的可靠成像技术，我们进行了以下基础实验和临床研究。(1)研制了适用于髋、膝关节3-T MR成像的新型射频线圈。研究了信号采集能力、信号均匀性和安全性。(2)开发了专门用于评估髋关节和膝关节软骨MR图像的计算机程序。使用该程序，软骨基质的厚度和MR参数（T2值）计算在不同的位置，具有较高的重复性。(3)本文采用人股骨头骨折患者的软骨-骨标本，研究了软骨MR参数与软骨基质蛋白多糖、胶原和水含量的相关性。在这些基质中，胶原含量与MR T2值高度相关。(4)磁共振图像T2测量的可行性 关于我们 对髋关节发育不良患者的髋臼和股骨软骨早期变化进行了评估。应用3 T磁共振成像对9例正常志愿者（9髋）和14例髋关节发育不良患者（15髋）的髋关节进行了SSTT 2成像。在正常组、关节炎前组和早期关节炎组中，比较髋臼和股骨软骨上级区的T2值和T2标测的视觉外观，包括梯度T2、低T2和高T2模式。T2标测分类能够早期检测髋关节发育不良患者的骨关节炎变性和软骨基质发育障碍。(5)采用软骨T2作为软骨基质变化的替代物，前瞻性评估了采用机械负荷系统进行MR成像评价膝关节承重功能的临床可行性。使用3.0 T MR成像获得了22名健康志愿者（9名男性，13名女性;平均年龄25岁）内侧和外侧股胫关节的矢状T2图。在负载条件下，在MR成像期间施加50%体重的轴向压缩力。在负重区的股骨和胫骨软骨的T2值之间的加载和卸载条件进行了比较。磁共振成像与机械负荷的临床可行性被证明，以检测在加载过程中的软骨T2的特定位点的变化。从负载的响应性，T2评估可以允许敏感地检测软骨和半月板中的早期退行性变化，通过揭示与软骨中的局部应力集中相关的病理状况。少

To investigate reliable imaging technology with less invasiveness for patients with joint disorder, such as osteoarthritis, we conducted following basic experiments and clinical investigations.(1) New radio-frequency (RF) coils, which are applicable to 3-T MR imaging, were developed for hip and knee joint. Ability of signal acquisition, signal uniformity, and safety were investigated.(2) Computer programs specific to assessment of hip and knee cartilage on MR images were developed. Using the programs, thickness and MR parameters (T2 values) of cartilage matrix were calculated at various sites, with high reproducibility.(3) Using resected human cartilage-bone specimen from patients with fracture of the femoral head, correlation of MR parameters of cartilage and cartilage matrix quantity such as proteoglycan, collagen and water, were evaluated. Among those matrixes, collagen content was highly associated with MR T2 values.(4) The feasibility of T2 assessment using magnetic resonance imag … More ing at 3T was assessed for evaluating early changes in the acetabular and femoral cartilages for patients with hip dysplasia. Sagittal T2 maps of the hip were obtained using 3T MR imaging in 9 normal volunteers (9 hips) and in 14 patients (15 hips) with hip dysplasia at pre-or early-arthritic stages. T2 values and the visual appearance of T2 mapping, including gradient T2,low T2,and high T2 patterns, were compared at the superior zones of the acetabular and femoral cartilages among the normal, pre-arthritic, and early-arthritic groups. T2 mapping classification enabled the early detection of osteoarthritic degeneration and the detection of developmental disorders of cartilage matrix in patients with hip dysplasia.(5) Clinical feasibility of MR imaging with a mechanical loading system for evaluation of load-bearing function in knee joints was prospectively assessed, using cartilage T2 as a surrogate of cartilage matrix changes. Sagittal T2 maps of the medial and lateral femoro-tibial joints of 22 healthy volunteers (nine men, 13 women; mean age, 25 years) were obtained using 3.0 T MR imaging. Under loading conditions, an axial compression force of 50% of body weight was applied during MR imaging. T2 values of the femoral and tibial cartilage at the weight-bearing area were compared between loading and unloading conditions. The clinical feasibility of MR imaging with mechanical loading was demonstrated to detect site-specific changes in cartilage T2 during loading. From responsiveness of loading, T2 evaluation may allow sensitive detection of early degenerative changes in the cartilage and meniscus, by revealing pathological conditions related to localized stress concentration in the cartilage. Less