Grant: Research Tools and Instruments

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.