BioMechanical Engineering Department, Delft University of Technology, Delft, The Netherlands.
Radiology and Nuclear Medicine Department, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
Int J Comput Assist Radiol Surg. 2019 Dec;14(12):2177-2186. doi: 10.1007/s11548-019-02029-6. Epub 2019 Jul 11.
The purpose is to design and validate an anthropomorphic polyvinyl alcohol (PVA) liver phantom with respiratory motion to simulate needle-based interventions. Such a system can, for example, be used as a validation tool for novel needles.
Image segmentations of CT scans of four patients during inspiration and expiration were used to measure liver and rib displacement. An anthropomorphic liver mold based on a CT scan was 3D printed and filled with 5% w/w PVA-to-water, undergoing two freeze-thaw cycles, in addition to a 3D-printed compliant rib cage. They were both held in place by a PVA abdominal phantom. A sinusoidal motion vector, based on the measured liver displacement, was applied to the liver phantom by means of a motion stage. Liver, rib cage and needle deflection were tracked by placing electromagnetic sensors on the phantom. Liver and rib cage phantom motion was validated by comparison with the CT images of the patients, whereas needle deflection was compared with the literature.
CT analysis showed that from the state of expiration to inspiration, the livers moved predominantly toward the right (mean: 2 mm, range: - 11 to 11 mm), anterior (mean: 15 mm, range: 9-21 mm) and caudal (mean: 16 mm, range: 6-24 mm) direction. The mechatronic design of the liver phantom gives the freedom to set direction and amplitude of the motion and was able to mimic the direction of liver motion of one patient. Needle deflection inside the phantom increased from 1.6 to 3.8 mm from the initial expiration state to inspiration.
The developed liver phantom allows for applying different motion patterns and shapes/sizes and thus allows for patient-specific simulation of needle-based interventions. Moreover, it is able to mimic appropriate respiratory motion and needle deflection as observed in patients.
设计并验证一种具有呼吸运动的仿人聚乙烯醇（PVA）肝脏体模，以模拟基于针的介入。例如，这样的系统可以用作新型针的验证工具。
使用四名患者在吸气和呼气时的 CT 扫描图像分割来测量肝脏和肋骨的位移。基于 CT 扫描的仿人肝脏模具通过 3D 打印制作，并填充 5%w/w 的 PVA 与水的混合物，经过两次冻融循环，此外还有一个 3D 打印的顺应性肋骨笼。它们都由 PVA 腹部体模固定。基于测量的肝脏位移的正弦运动矢量通过运动台施加到肝脏体模上。通过在体模上放置电磁传感器来跟踪肝脏、肋骨笼和针的偏斜。通过将肝脏和肋骨笼体模的运动与患者的 CT 图像进行比较来验证其运动，而将针的偏斜与文献进行比较。
CT 分析表明，从呼气状态到吸气状态，肝脏主要向右侧（平均：2 毫米，范围：-11 至 11 毫米）、前侧（平均：15 毫米，范围：9-21 毫米）和尾侧（平均：16 毫米，范围：6-24 毫米）移动。肝脏体模的机电设计提供了设置运动方向和幅度的自由度，并能够模拟一名患者的肝脏运动方向。针在体模内的偏斜从初始呼气状态增加到吸气状态，从 1.6 毫米增加到 3.8 毫米。
所开发的肝脏体模允许应用不同的运动模式和形状/大小，从而能够模拟基于针的介入的患者特异性。此外，它能够模拟患者中观察到的适当的呼吸运动和针的偏斜。
