Robot Assisted Multi-view 3D Echocardiography

超声心动图仍然是用于心功能分析和图像引导干预的最广泛的成像手段。超声心动图的优点包括缺乏电离辐射、便携性、低成本和比其他方式更高的时间分辨率。超声波技术的最新发展使心脏的三维(3D)采集成为可能，从而使复杂的心脏解剖结构可视化，并分析心脏*运动在3D空间中的复杂组合。几项研究表明，与基于二维采集的分析相比，3D图像采集*改善了体积分析。与计算机断层扫描和磁共振成像相比，3D*超声心动图的主要局限性包括视野有限(FOV)、依赖有限的声学窗口以及较低的信噪比。由于视野有限，一次超声心动图扫描可能不足以覆盖心脏的整个几何形状。为了增加视野，我们目前的工作使用光学跟踪系统来对准多个超声扫描，该系统不依赖于任何图像信息来对准。通过多摄像机光学跟踪系统在3D空间中跟踪连接到超声换能器的一组标记。一旦注册，小波传感器融合算法被用来将这些视图组合成均匀采样体数据集。不幸的是，光学跟踪系统受到视线限制，这使得在手术室条件下使用这项技术变得困难。其他限制是：(1)取决于患者相对于摄像机的位置的遮挡问题，(2)无法自动扫描过程，数字化过程完全是手动的，以及(3)超声技师在长时间操纵探头时感到疲劳。为了解决这些限制，我们建议在医疗机械臂上安装超声波探头。这里的主要想法是，超声波探头3D跟踪将由机器人编码器执行，而不需要在患者周围部署*多个摄像头。不会有光学*遮挡问题，ARM将允许我们自动化一些数字化*功能。通过使用该医疗机器人，我们将专注于以下几个方面的研究：(1)开发新的半自主多视角融合算法；(2)利用人机协作来减少超声诊断员的疲劳。

Echocardiography remains*the most widely used image modality for cardiac functional analysis and*image-guided interventions. The advantages of echocardiography include lack of*ionizing radiation, portability, low cost, and higher temporal resolution than*other modalities. Recent developments in ultrasound technology enabled*three-dimensional (3D) acquisitions of the heart, which allow visualization of*the complex cardiac anatomy, and analysis of the complex combination of cardiac*motions in 3D space. Several studies have shown that 3D image acquisition*improves volumetric analysis, in comparison to the analysis based on a*two-dimensional acquisition. Major limitations of the 3D*echocardiography in comparison to computed tomography and magnetic*resonance imaging include limited field of view (FOV), reliance on*frequently limited acoustic windows, and poor signal to noise ratio. Due*to limited FOV, a single echocardiography scan may not be enough to cover the*whole geometry of the heart. To increase the FOV our current work uses an optical tracking system to align multiple ultrasound scans that does not rely on any image information for alignment. A set of markers attached to the ultrasound transducer are tracked in 3D space by a multi-camera optical tracking system. Once registered, a wavelet sensor fusion algorithm is used to combined those views into a uniformly sampled volumetric data set. Unfortunately optical tracking*systems are subject to the line-of-sight limitation which make it difficult to use this technique in operating room conditions. Other limitations are: (1) occlusion problems that depend on the patient positioning relative to the cameras, (2) inability to automate scanning procedures, the digitizing process is purely manual, and (3) sonographer fatigue during long manipulations of the probe. To*solve these limitations, we propose to install the ultrasound probe on a*medical robotic arm. The main idea here is that the ultrasound*probe 3D tracking will be performed by the robot encoders and will not require*the deployment of multiple cameras around the patient. There will be no optical*occlusion problems and the arm will allow us to automate some of the digitizing*functions. By using this medical robot, we will focus our research on the*following: (1) develop new semi-autonomous multi-view*fusion algorithms, (2) reduce sonographer fatigue*using human-robot cooperation.