3-Dimensional Ultrasound Imaging for Medical Telesonography: Algorithms and Architectures

Enabling telemedicine in Ultrasound (US) imaging, i.e. telesonography, is until today just a wish. Although US has incomparable advantages such as safety in use, lower cost and complexity, and capability to be utilized in many applications, it is limited in use to hospitals and sonographer cabinets. Medical US has not been available yet in many situations of need. For example, a patient with a cardiac complication on a ship or aircraft may lose his life due to the impossibility to perform a scan on-site and get a remote diagnosis quickly. Even rescue vehicles and helicopters have not been equipped yet with US device that can be operated by a basic trained paramedic. Populations in isolated remote areas seldom enjoy access to sonographers, and are in a serious necessity to unlock telesonography with an affordable (solving the typical low medical-equipment budget) and battery operated (working around the common electricity cut-offs problem or lack thereof) mean. The high reliance on the presence of a trained sonographer to perform the scan is the main reason behind this shortcoming. A sonographer is required to move the probe on the body based on high experience, fine precision, and learned technique until reaching the diagnosis on-the-spot. 3D US lifts this limitation by imaging the whole volume under the probe at once, and accordingly allows the decoupling of the acquisition from the diagnosis. Therefore, any untrained person on-site can acquire 3D scans and send the reconstructions to a hospital for diagnosis. However, today¿s 3D systems only suit well-equipped hospitals due to their high requirements in size, power, and cost. In order to solve the root of this vicious cycle, there is a need for a medical US system that supports 3D imaging, is compact and power efficient. This thesis is a step towards solving this problem. An unprecedented single-FPGA 3D medical US imaging system with a 5 W consumption has been proposed. Our imaging system features: (i) 1024 channel of independent information processing (state-of-the-art), (ii) two input means: realtime data via optical connection with a US transducer, and offline data via Ethernet, (iii) complete digital processing platform from the receive of the digitized raw data until the rendering of the reconstruction on a screen, (iv) three common US imaging modes for image enhancement flexibility at the cost of the frame rate, (v) extreme scalability: downscaling for 2D imaging, or further upscaling on a resources-capable FPGA, and (vi) high-definition live video output of the scans. We have developed a prototype whose size is currently 26.7cm×14cm×0.16cm. The material cost is less than 4000 USD, with a path to further reduction by implementing a custom board around the FPGA for mass production, instead of the off-the- shelf development board. This compares very favorably to current commercial 3D systems, which cost [approx.]100K$ for the imaging system only. Moreover, in order to bridge the gap arising from the decoupling of the scanning process from the interpretation by an US radiologist, two solutions have been proposed: (i) automatic probe localization module using gyroscopes and accelerometers, and (ii) a mobile application for probe positioning guidance for common US scans. Our contributions have been consolidated to successfully achieve the aimed target of a first telesonography-capable prototype allowing the usage of medical US anywhere and by any personnel, with major societal benefits.