Centre for Hip Health and Mobility, University of British Columbia, Vancouver, Canada.
Department of Family Practice, University of British Columbia, Vancouver, Canada.
J Magn Reson Imaging. 2018 Mar;47(3):841-847. doi: 10.1002/jmri.25823. Epub 2017 Aug 21.
To develop methods for evaluating 3D patellofemoral and tibiofemoral alignment in vertical open-bore magnetic resonance (MR) scanners, with participants upright and fully weight-bearing; and to evaluate the repeatability of these methods in individuals with patellofemoral osteoarthritis (OA) and in asymptomatic knees.
Our methods extend previously validated, reliable methods for evaluating alignment into an upright MR environment. In 10 participants with early patellofemoral OA and 10 with asymptomatic knees, we acquired sagittal T -weighted turbo spin echo images in a 3T scanner to create accurate participant-specific 3D anatomical surface models. In a vertical open-bore 0.5T MR scanner, we obtained lower-resolution sagittal gradient echo images to capture bony position and orientation data. Participants were scanned in a position of squatting with the knees flexed 30°, three separate times to evaluate repeatability. Bone segmentation was performed manually, surface models were registered to data from the 0.5T scanner, and 3D patellofemoral and tibiofemoral alignment was calculated in all six degrees of freedom (three rotations and three translations).
Intraclass correlation coefficients (ICCs) were ≥0.94, with the exception of patellar spin (0.79). Standard errors of measure (SEM) were <2° rotation and <0.9 mm translation. Repeatability remained adequate when stratified by group, with the exception of patellar spin (ICC 0.57 for asymptomatic knees vs. 0.91 for OA knees).
We demonstrate methods for evaluating 3D alignment in upright fully weight-bearing participant positions in a vertical open-bore MR scanner. With the exception of patellar spin, repeatability was good to excellent.
3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:841-847.
开发在垂直开放式磁共振（MR）扫描仪中评估 3D 髌股和胫股对线的方法，使参与者保持直立和完全负重；并评估这些方法在髌股关节炎（OA）患者和无症状膝关节中的重复性。
我们的方法将先前验证过的、可靠的对线评估方法扩展到直立的 MR 环境中。在 10 名早期髌股 OA 患者和 10 名无症状膝关节患者中，我们在 3T 扫描仪中采集矢状 T1 加权涡轮自旋回波图像，以创建准确的个体化 3D 解剖表面模型。在垂直开放式 0.5T MR 扫描仪中，我们获得较低分辨率的矢状梯度回波图像，以获取骨骼位置和方向数据。参与者在深蹲位置接受扫描，膝关节弯曲 30°，三次重复以评估重复性。手动进行骨骼分割，将表面模型注册到 0.5T 扫描仪的数据中，并在所有六个自由度（三个旋转和三个平移）中计算 3D 髌股和胫股对线。
除髌股旋转（0.79）外，组内相关系数（ICC）均≥0.94。测量标准误差（SEM）<2°旋转和<0.9mm 平移。除髌股旋转外（无症状膝关节的 ICC 为 0.57，OA 膝关节的 ICC 为 0.91），按组分层时，重复性仍较好。
我们证明了在垂直开放式磁共振扫描仪中评估直立完全负重参与者位置 3D 对线的方法。除髌股旋转外，重复性良好至优秀。
3 技术功效：阶段 1 J. Magn. Reson. Imaging 2018;47:841-847.
