Transrectal ultrasound (TRUS) guided needle biopsy is currently the clinical routine for diagnosis of prostate cancer. Due to the blurry TRUS imaging, magnetic resonance imaging (MRI) of prostate is usually taken prior to the biopsy procedure to assist needle target planning. In this paper, a novel geometric transformation method, which is based on the mechanics of materials, is proposed to facilitate the deformable registration of lesion sites from MRI to ultrasound imaging. In the method an enlarged shell, scaled from the geometry of prostate constructed from ultrasound imaging, is used to squeeze the prostate constructed from MRI imaging. The prostate can automatically rotate and position itself towards the target geometry, and deforms to match the target throughout the entire volumes. Transformations of 3D volumes as well as 2D sections of prostate are carried out to evaluate the transformation performance with respect to different material properties and segmentation errors. Some practical issues on applying the method to clinical biopsy operations are discussed. We show that this FEM based transformation method is promising in deformable registration and could be used in other organ image registrations.

中文翻译：

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有限元法几何变换前列腺变形配准

经直肠超声 (TRUS) 引导的穿刺活检是目前诊断前列腺癌的临床常规。由于 TRUS 成像模糊，通常在活检程序之前对前列腺进行磁共振成像 (MRI) 以协助针目标规划。在本文中，提出了一种基于材料力学的新型几何变换方法，以促进从 MRI 到超声成像的病变部位的可变形配准。在该方法中，使用从超声成像构建的前列腺几何结构缩放的放大外壳来挤压从 MRI 成像构建的前列腺。前列腺可以自动旋转并朝向目标几何体定位，并在整个体积中变形以匹配目标。进行 3D 体积和前列腺的 2D 切片的转换，以评估关于不同材料特性和分割错误的转换性能。讨论了将该方法应用于临床活检操作的一些实际问题。我们表明这种基于 FEM 的变换方法在可变形配准中很有前景，并可用于其他器官图像配准。