Berendsen F F, Kotte A N T J, de Leeuw A A C, Jürgenliemk-Schulz I M, Viergever M A, Pluim J P W
Image Sciences Institute, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
Phys Med Biol. 2014 Aug 7;59(15):4033-45. doi: 10.1088/0031-9155/59/4/4033. Epub 2014 Jul 3.
A serious challenge in image registration is the accurate alignment of two images in which a certain structure is present in only one of the two. Such topological changes are problematic for conventional non-rigid registration algorithms. We propose to incorporate in a conventional free-form registration framework a geometrical penalty term that minimizes the volume of the missing structure in one image. We demonstrate our method on cervical MR images for brachytherapy. The intrapatient registration problem involves one image in which a therapy applicator is present and one in which it is not. By including the penalty term, a substantial improvement in the surface distance to the gold standard anatomical position and the residual volume of the applicator void are obtained. Registration of neighboring structures, i.e. the rectum and the bladder is generally improved as well, albeit to a lesser degree.
图像配准中的一个严峻挑战是准确对齐两幅图像，其中特定结构仅存在于这两幅图像中的一幅中。这种拓扑变化对于传统的非刚性配准算法来说是个难题。我们建议在传统的自由形式配准框架中纳入一个几何惩罚项，该惩罚项能使一幅图像中缺失结构的体积最小化。我们在用于近距离放射治疗的宫颈磁共振图像上演示了我们的方法。患者体内配准问题涉及一幅有治疗施源器的图像和一幅没有治疗施源器的图像。通过纳入惩罚项，在到金标准解剖位置的表面距离以及施源器空洞的残余体积方面都取得了显著改善。相邻结构（即直肠和膀胱）的配准通常也有所改善，尽管程度较小。
