Center of Mathematics for Applications, University of Oslo, Oslo, Norway.
Int J Comput Assist Radiol Surg. 2009 May;4(3):215-23. doi: 10.1007/s11548-009-0291-4. Epub 2009 Feb 24.
We present a system which supports deformable image registration guided by a haptic device.
The haptic device is tied to a block matching method where a set of uniformly distributed control points determine the block positions. Each control point constitutes a particle in a mass spring grid which limits the space of allowed movements to elastic movements. Control points are manipulated by the haptic device, and the negative gradient of the similarity metric over the corresponding block is rendered as a force on the haptic device guiding the user to a minimum of the optimization landscape. Fast update of forces was achieved by exploiting the GPU for computations of the similarity metric and for interpolation of the deformation field.
We show that haptic guided registration facilitates faster and improved registration compared to using a purely visual alignment in a user study on synthetic images. We also demonstrate feasibility of applying the system on medical images through a comparison with an automatic block matching algorithm. A radiologist performing registration with the haptic registration system posted faster registration times and better registration results than the automatic block matching algorithm when using identical grid and block sizes.
Possible applications of the system are refinement of registration results from automatic registration methods and construction of initial state used in automatic deformable registration methods.
我们提出了一种由触觉设备引导的可变形图像配准系统。
触觉设备与块匹配方法绑定，其中一组均匀分布的控制点确定块的位置。每个控制点构成质量弹簧网格中的一个粒子，该网格限制了允许的运动空间为弹性运动。通过触觉设备来操纵控制点，并且相似性度量的负梯度在相应的块上呈现为引导用户到优化景观最小值的力。通过利用 GPU 进行相似性度量的计算和变形场的插值，实现了快速更新力。
我们通过在合成图像的用户研究中展示，与仅使用视觉对准相比，触觉引导的配准可以更快地进行并改善配准。我们还通过与自动块匹配算法的比较，证明了该系统在医学图像上应用的可行性。与自动块匹配算法相比，放射科医生使用触觉配准系统进行配准时，使用相同的网格和块大小时，配准时间更快，配准结果更好。
该系统的可能应用包括细化自动配准方法的配准结果以及构建自动变形配准方法中使用的初始状态。
