Rigid and Non-Rigid Motion Compensation in Weight-Bearing CBCT of the Knee Using Simulated Inertial Measurements.
Rigid and Non-Rigid Motion Compensation in Weight-Bearing CBCT of the Knee Using Simulated Inertial Measurements.
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DOI：
10.1109/tbme.2021.3123673
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发表时间：
2022-05
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受试者不自主运动是膝关节负重锥束 CT 伪影的主要来源。为了实现临床诊断的图像质量，需要补偿运动。我们建议使用连接到腿部的惯性测量单元（IMU）进行运动估计。我们使用光学跟踪系统记录的真实运动进行模拟研究。评估了三种基于 IMU 的校正方法，即刚性运动校正、非刚性 2D 投影变形和非刚性 3D 动态重建。我们提出了基于系统几何形状的初始化过程。通过 IMU 噪声仿真，我们研究了所提出的方法在实际应用中的适用性。所有提出的基于 IMU 的方法都可以纠正运动，至少与最先进的基于标记的方法一样好。与未校正的情况相比，无运动体积和运动校正体积之间的结构相似性指数和均方根误差分别提高了 24-35% 和 78-85%。噪声分析表明，商用 IMU 的噪声水平需要提高 105 倍，目前只能通过对于应用而言不够强大的专用硬件来实现。我们的模拟研究证实了这种新颖方法的可行性，并定义了实际应用所需的改进。所提出的工作为膝关节锥束 CT 中基于 IMU 的运动补偿奠定了基础，并为未来的发展创造了宝贵的见解。
Involuntary subject motion is the main source of artifacts in weight-bearing cone-beam CT of the knee. To achieve image quality for clinical diagnosis, the motion needs to be compensated. We propose to use inertial measurement units (IMUs) attached to the leg for motion estimation. We perform a simulation study using real motion recorded with an optical tracking system. Three IMU-based correction approaches are evaluated, namely rigid motion correction, non-rigid 2D projection deformation and non-rigid 3D dynamic reconstruction. We present an initialization process based on the system geometry. With an IMU noise simulation, we investigate the applicability of the proposed methods in real applications. All proposed IMU-based approaches correct motion at least as good as a state-of-the-art marker-based approach. The structural similarity index and the root mean squared error between motion-free and motion corrected volumes are improved by 24-35% and 78-85%, respectively, compared with the uncorrected case. The noise analysis shows that the noise levels of commercially available IMUs need to be improved by a factor of 105 which is currently only achieved by specialized hardware not robust enough for the application. Our simulation study confirms the feasibility of this novel approach and defines improvements necessary for a real application. The presented work lays the foundation for IMU-based motion compensation in cone-beam CT of the knee and creates valuable insights for future developments.