Effect of Patient Arm Motion in Whole-Body PET/CT
Effect of Patient Arm Motion in Whole-Body PET/CT
复制标题
患者手臂运动对全身 PET/CT 的影响
作者：
M. Lodge;J. Mhlanga;Steve Y. Cho;R. Wahl
在全身PET/CT采集过程中，手臂的运动并不少见，并且会在PET图像上引起明显的冷伪影。我们调查了这些伪像背后的机制，并提出了一个潜在的解决方案。方法：以5例疑似手臂运动的临床病例为研究对象，设计体模实验。实验包括一个中心直径20厘米的68Ge/68Ga圆柱体模拟颈部和两个外围直径10厘米直径的18F圆柱体模拟手臂。在全身PET/CT系统上进行自由运动CT和PET后，改变手臂的位置，以引入不同程度的错位。在这个位置进行了20次连续的PET扫描，随着18F的衰减，在二维(2D)和三维(3D)采集之间交替进行。18F在武器中的衰变，而68Ge/68Ga钢瓶中的活度保持大致恒定，使散射和衰减校正误差的相对影响得以确定。结果：2D图像伪影主要局限于局部运动区域，而3D图像伪影扩展到整个受影响的切片，表现为对放射性示踪剂浓度的明显低估，随着偏差的增加而变得更加明显。对于3d，散射修正误差依赖于臂中的活动，但对于典型的活度浓度，散射修正误差比衰减修正误差更显著。没有散射校正的3D图像重建基本上消除了模体和患者图像中的这些伪影。结论：患者手臂运动引起的重建伪影可能是实质性的，应予以认识，因为它们会影响PET的定性和定量评估。
Arm motion during whole-body PET/CT acquisition is not uncommon and can give rise to striking cold artifacts on PET images. We investigated the mechanisms that underlie these artifacts and proposed a potential solution. Methods: A phantom experiment based on 5 clinical cases of suspected arm motion was designed. The experiment involved a central 20-cm-diameter 68Ge/68Ga cylinder simulating the neck and 2 peripheral 10-cm-diameter 18F cylinders simulating arms. After motion-free CT and PET on a whole-body PET/CT system, the position of the arms was altered so as to introduce different amounts of misalignment. Twenty sequential PET scans were acquired in this position, alternating between 2-dimensional (2D) and 3-dimensional (3D) acquisition, as the 18F decayed. Decay of 18F in the arms, while the activity in the 68Ge/68Ga cylinder remained approximately constant, allowed the relative impact of scatter and attenuation-correction errors to be determined. Results: Image artifacts were largely confined to the local region of motion in 2D but extended throughout the affected slices in 3D, where they manifested as a striking underestimation of radiotracer concentration that became more significant with increasing misalignment. For 3D, scatter-correction error depended on activity in the arms, but for typical activity concentrations scatter-correction error was more significant than attenuation-correction error. 3D image reconstruction without scatter correction substantially eliminated these artifacts in both phantom and patient images. Conclusion: Reconstruction artifacts due to patient arm motion can be substantial and should be recognized because they can affect both qualitative and quantitative assessment of PET.
影响因子：
3.8
作者：
Kinahan, PE;Townsend, DW;Sashin, D
通讯作者：
Sashin, D