Urish Kenneth L, Williams Ashley A, Durkin John R, Chu Constance R
Department of Orthopaedics and Rehabilitation, Penn State Milton S. Hershey Medical Center, Hershey PA, USA.
Cartilage. 2013 Jan;4(1):20-27. doi: 10.1177/1947603512451745.
Although conventional radiography is used to assess osteoarthritis in a clinical setting, it has limitations, including an inability to stage early cartilage degeneration. There is a growing interest in using quantitative magnetic resonance imaging to identify degenerative changes in articular cartilage, including the large multicentered study, the Osteoarthritis Initiative (OAI). There is a demand for suitable image registration and segmentation software to complete this analysis. The objective of this study was to develop and validate the open source software, ImageK, that registers 3 T MRI T2 mapping and double echo steady state (DESS) knee MRI sequences acquired in the OAI protocol.
A C++ library, the insight toolkit, was used to develop open source software to register DESS and T2 mapping image MRI sequences using Mattes's Multimodality Mutual information metric.
Registration was assessed using three separate methods. A checkerboard layout demonstrated acceptable visual alignment. Fiducial markers placed in cadaveric knees measured a registration error of 0.85 voxels. Measuring the local variation in Mattes's Mutual Information metric in the local area of the registered solution showed precision within 1 pixel. In this group, the registered solution required a transform of 56 voxels in translation and 1 degree of rotation.
The software we have developed, ImageK, provides free, open source image analysis software that registers DESS and T2 mapping sequences of knee articular cartilage within 1 voxel accuracy. This image registration software facilitates quantitative MRI analyses of knee articular cartilage.
尽管传统放射摄影术在临床环境中用于评估骨关节炎，但它存在局限性，包括无法对早期软骨退变进行分期。人们越来越关注使用定量磁共振成像来识别关节软骨的退变变化，其中包括大型多中心研究——骨关节炎倡议（OAI）。需要合适的图像配准和分割软件来完成此分析。本研究的目的是开发并验证开源软件ImageK，该软件可对在OAI协议中获取的3T磁共振成像T2映射和双回波稳态（DESS）膝关节磁共振成像序列进行配准。
使用一个C++库——洞察工具包，开发开源软件，使用马特斯多模态互信息度量对DESS和T2映射图像磁共振成像序列进行配准。
使用三种不同方法评估配准情况。棋盘格布局显示出可接受的视觉对齐。放置在尸体膝关节中的基准标记测量出配准误差为0.85体素。在配准解决方案的局部区域测量马特斯互信息度量的局部变化，显示精度在1像素以内。在该组中，配准解决方案需要56体素的平移变换和1度的旋转变换。
我们开发的软件ImageK提供了免费的开源图像分析软件，可在1体素精度内对膝关节软骨的DESS和T2映射序列进行配准。这种图像配准软件便于对膝关节软骨进行定量磁共振成像分析。
