School of Integrated Technology and Yonsei Institute of Convergence Technology, Yonsei University, Yeonsu-gu, Incheon, South Korea.
PLoS One. 2021 Jan 14;16(1):e0227656. doi: 10.1371/journal.pone.0227656. eCollection 2021.
Several sinogram inpainting based metal artifact reduction (MAR) methods have been proposed to reduce metal artifact in CT imaging. The sinogram inpainting method treats metal trace regions as missing data and estimates the missing information. However, a general assumption with these methods is that data truncation does not occur and that all metal objects still reside within the field-of-view (FOV). These assumptions are usually violated when the FOV is smaller than the object. Thus, existing inpainting based MAR methods are not effective. In this paper, we propose a new MAR method to effectively reduce metal artifact in the presence of data truncation. The main principle of the proposed method involves using a newly synthesized sinogram instead of the originally measured sinogram. The initial reconstruction step involves obtaining a small FOV image with the truncation artifact removed. The final step is to conduct sinogram inpainting based MAR methods, i.e., linear and normalized MAR methods, on the synthesized sinogram from the previous step. The proposed method was verified for extended cardiac-torso simulations, clinical data, and experimental data, and its performance was quantitatively compared with those of previous methods (i.e., linear and normalized MAR methods directly applied to the originally measured sinogram data). The effectiveness of the proposed method was further demonstrated by reducing the residual metal artifact that were present in the reconstructed images obtained using the previous method.
已经提出了几种基于正弦图补全的金属伪影减少（MAR）方法来减少 CT 成像中的金属伪影。正弦图补全方法将金属痕迹区域视为缺失数据，并估计缺失信息。然而，这些方法的一个普遍假设是数据截断不会发生，并且所有金属物体仍然位于视野（FOV）内。当 FOV 小于物体时，这些假设通常会被违反。因此，现有的基于补全的 MAR 方法并不有效。在本文中，我们提出了一种新的 MAR 方法，以在存在数据截断的情况下有效减少金属伪影。该方法的主要原理涉及使用新合成的正弦图代替原始测量的正弦图。初始重建步骤涉及获得具有截断伪影去除的小 FOV 图像。最后一步是在前一步骤中对合成的正弦图进行基于补全的 MAR 方法，即线性和归一化 MAR 方法。该方法已在扩展心脏-胸部模拟、临床数据和实验数据中进行了验证，并与之前的方法（即直接应用于原始测量的正弦图数据的线性和归一化 MAR 方法）进行了定量比较。通过减少先前方法获得的重建图像中存在的残留金属伪影，进一步证明了该方法的有效性。
