4D-MRI 数据的非刚性图像配准，以提高移动肿瘤的勾画精度。
Non-rigid image registration of 4D-MRI data for improved delineation of moving tumors.
机构信息
Department of Radiation Oncology, University of Wuerzburg, Josef-Schneider-Str. 11, 97080, Wuerzburg, Germany.
Department of Diagnostic and Interventional Radiology, University of Wuerzburg, Wuerzburg, Germany.
出版信息
BMC Med Imaging. 2020 Apr 23;20(1):41. doi: 10.1186/s12880-020-00439-6.
BACKGROUND
To increase the image quality of end-expiratory and end-inspiratory phases of retrospective respiratory self-gated 4D MRI data sets using non-rigid image registration for improved target delineation of moving tumors.
METHODS
End-expiratory and end-inspiratory phases of volunteer and patient 4D MRI data sets are used as targets for non-rigid image registration of all other phases using two different registration schemes: In the first, all phases are registered directly (dir-Reg) while next neighbors are successively registered until the target is reached in the second (nn-Reg). Resulting data sets are quantitatively compared using diaphragm and tumor sharpness and the coefficient of variation of regions of interest in the lung, liver, and heart. Qualitative assessment of the patient data regarding noise level, tumor delineation, and overall image quality was performed by blinded reading based on a 4 point Likert scale.
RESULTS
The median coefficient of variation was lower for both registration schemes compared to the target. Median dir-Reg coefficient of variation of all ROIs was 5.6% lower for expiration and 7.0% lower for inspiration compared with nn-Reg. Statistical significant differences between the two schemes were found in all comparisons. Median sharpness in inspiration is lower compared to expiration sharpness in all cases. Registered data sets were rated better compared to the targets in all categories. Over all categories, mean expiration scores were 2.92 ± 0.18 for the target, 3.19 ± 0.22 for nn-Reg and 3.56 ± 0.14 for dir-Reg and mean inspiration scores 2.25 ± 0.12 for the target, 2.72 ± 215 0.04 for nn-Reg and 3.78 ± 0.04 for dir-Reg.
CONCLUSIONS
In this work, end-expiratory and inspiratory phases of a 4D MRI data sets are used as targets for non-rigid image registration of all other phases. It is qualitatively and quantitatively shown that image quality of the targets can be significantly enhanced leading to improved target delineation of moving tumors.
背景
为了提高回顾性呼吸自门控 4D MRI 数据集在末期呼气和末期吸气相的图像质量，以便更好地勾画移动肿瘤的靶区，使用非刚性图像配准对末期呼气和末期吸气相进行图像配准。
方法
使用志愿者和患者的 4D MRI 数据集的末期呼气和末期吸气相作为所有其他相位的非刚性图像配准的目标，使用两种不同的配准方案：在第一种方案中，所有相位直接配准（dir-Reg），而在下一种方案中，依次对相邻相位进行配准，直到达到目标（nn-Reg）。使用膈肌和肿瘤锐利度以及肺、肝和心脏的感兴趣区域的变异系数，对所得数据集进行定量比较。通过基于 4 分制的盲法阅读，对患者数据的噪声水平、肿瘤勾画和整体图像质量进行定性评估。
结果
与目标相比，两种配准方案的变异系数中位数均较低。与 nn-Reg 相比，所有 ROI 的 dir-Reg 变异系数中位数在呼气时降低了 5.6%，在吸气时降低了 7.0%。在所有比较中，两种方案之间均存在统计学显著差异。在所有情况下，吸气时的中位锐利度均低于呼气时的锐利度。与目标相比，注册数据集在所有类别中的评分均更好。在所有类别中，目标的平均呼气评分分别为 2.92±0.18，nn-Reg 为 3.19±0.22，dir-Reg 为 3.56±0.14，目标的平均吸气评分分别为 2.25±0.12，nn-Reg 为 2.72±0.04，dir-Reg 为 3.78±0.04。
结论
在这项工作中，4D MRI 数据集的末期呼气和末期吸气相被用作所有其他相位的非刚性图像配准的目标。从定性和定量两方面都表明，目标的图像质量可以得到显著提高，从而改善移动肿瘤的靶区勾画。
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