Tahmasebi Amir M, Sharifi Reza, Agarwal Harsh K, Turkbey Baris, Bernardo Marcelino, Choyke Peter, Pinto Peter, Wood Bradford, Kruecker Jochen
Philips Research North America, Briarcliff Manor, NY, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2012;2012:5412-5. doi: 10.1109/EMBC.2012.6347218.
In prostate brachytherapy procedures, combining high-resolution endorectal coil (ERC)-MRI with Computed Tomography (CT) images has shown to improve the diagnostic specificity for malignant tumors. Despite such advantage, there exists a major complication in fusion of the two imaging modalities due to the deformation of the prostate shape in ERC-MRI. Conventionally, nonlinear deformable registration techniques have been utilized to account for such deformation. In this work, we present a model-based technique for accounting for the deformation of the prostate gland in ERC-MR imaging, in which a unique deformation vector is estimated for every point within the prostate gland. Modes of deformation for every point in the prostate are statistically identified using a set of MR-based training set (with and without ERC-MRI). Deformation of the prostate from a deformed (ERC-MRI) to a non-deformed state in a different modality (CT) is then realized by first calculating partial deformation information for a limited number of points (such as surface points or anatomical landmarks) and then utilizing the calculated deformation from a subset of the points to determine the coefficient values for the modes of deformations provided by the statistical deformation model. Using a leave-one-out cross-validation, our results demonstrated a mean estimation error of 1mm for a MR-to-MR registration.
在前列腺近距离放射治疗过程中，将高分辨率直肠内线圈（ERC）-磁共振成像（MRI）与计算机断层扫描（CT）图像相结合已显示出可提高对恶性肿瘤的诊断特异性。尽管有这样的优势，但由于ERC-MRI中前列腺形状的变形，两种成像模态的融合存在一个主要并发症。传统上，已采用非线性可变形配准技术来处理这种变形。在这项工作中，我们提出了一种基于模型的技术来处理ERC-MR成像中前列腺的变形，其中为前列腺内的每个点估计一个唯一的变形向量。使用一组基于磁共振的训练集（有和没有ERC-MRI）对前列腺中每个点的变形模式进行统计识别。然后，通过首先计算有限数量点（如表面点或解剖标志点）的部分变形信息，然后利用从这些点的子集中计算出的变形来确定统计变形模型提供的变形模式的系数值，实现前列腺从变形状态（ERC-MRI）到不同模态（CT）下非变形状态的变形。使用留一法交叉验证，我们的结果表明，对于MR-to-MR配准，平均估计误差为1毫米。
