Departments of Medical Informatics and Radiology, Erasmus MC - University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
Med Image Anal. 2011 Apr;15(2):238-49. doi: 10.1016/j.media.2010.10.003. Epub 2010 Oct 28.
A registration method for motion estimation in dynamic medical imaging data is proposed. Registration is performed directly on the dynamic image, thus avoiding a bias towards a specifically chosen reference time point. Both spatial and temporal smoothness of the transformations are taken into account. Optionally, cyclic motion can be imposed, which can be useful for visualization (viewing the segmentation sequentially) or model building purposes. The method is based on a 3D (2D+time) or 4D (3D+time) free-form B-spline deformation model, a similarity metric that minimizes the intensity variances over time and constrained optimization using a stochastic gradient descent method with adaptive step size estimation. The method was quantitatively compared with existing registration techniques on synthetic data and 3D+t computed tomography data of the lungs. This showed subvoxel accuracy while delivering smooth transformations, and high consistency of the registration results. Furthermore, the accuracy of semi-automatic derivation of left ventricular volume curves from 3D+t computed tomography angiography data of the heart was evaluated. On average, the deviation from the curves derived from the manual annotations was approximately 3%. The potential of the method for other imaging modalities was shown on 2D+t ultrasound and 2D+t magnetic resonance images. The software is publicly available as an extension to the registration package elastix.
提出了一种用于动态医学成像数据中运动估计的配准方法。配准直接在动态图像上进行，从而避免了对特定选择的参考时间点的偏差。变换的空间和时间平滑度都被考虑在内。可选地，可以施加循环运动，这对于可视化（顺序查看分割）或模型构建目的很有用。该方法基于 3D（2D+时间）或 4D（3D+时间）自由形式 B 样条变形模型、一种相似性度量，该度量最小化随时间的强度方差，并使用具有自适应步长估计的随机梯度下降方法进行约束优化。该方法在合成数据和肺部的 3D+t 计算机断层扫描数据上与现有的注册技术进行了定量比较。这表明在提供平滑变换的同时具有亚像素精度，并且注册结果具有高度一致性。此外，还评估了从心脏的 3D+t 计算机断层血管造影数据半自动推导左心室容积曲线的准确性。平均而言，从手动注释中推导的曲线的偏差约为 3%。该方法在其他成像模式上的潜力在 2D+t 超声和 2D+t 磁共振图像上得到了展示。该软件作为 elastix 注册包的扩展，可供公众使用。
