Algorithm and Hardware Design for High Volume Rate 3-D Medical Ultrasound Imaging

abstract: Ultrasound B-mode imaging is an increasingly significant medical imaging modality for clinical applications. Compared to other imaging modalities like computed tomography (CT) or magnetic resonance imaging (MRI), ultrasound imaging has the advantage of being safe, inexpensive, and portable. While two dimensional (2-D) ultrasound imaging is very popular, three dimensional (3-D) ultrasound imaging provides distinct advantages over its 2-D counterpart by providing volumetric imaging, which leads to more accurate analysis of tumor and cysts. However, the amount of received data at the front-end of 3-D system is extremely large, making it impractical for power-constrained portable systems. In this thesis, algorithm and hardware design techniques to support a hand-held 3-D ultrasound imaging system are proposed. Synthetic aperture sequential beamforming (SASB) is chosen since its computations can be split into two stages, where the output generated of Stage 1 is significantly smaller in size compared to the input. This characteristic enables Stage 1 to be done in the front end while Stage 2 can be sent out to be processed elsewhere. The contributions of this thesis are as follows. First, 2-D SASB is extended to 3-D. Techniques to increase the volume rate of 3-D SASB through a new multi-line firing scheme and use of linear chirp as the excitation waveform, are presented. A new sparse array design that not only reduces the number of active transducers but also avoids the imaging degradation caused by grating lobes, is proposed. A combination of these techniques increases the volume rate of 3-D SASB by 4\texttimes{} without introducing extra computations at the front end. Next, algorithmic techniques to further reduce the Stage 1 computations in the front end are presented. These include reducing the number of distinct apodization coefficients and operating with narrow-bit-width fixed-point data. A 3-D die stacked architecture is designed for the front end. This highly parallel architecture enables the signals received by 961 active transducers to be digitalized, routed by a network-on-chip, and processed in parallel. The processed data are accumulated through a bus-based structure. This architecture is synthesized using TSMC 28 nm technology node and the estimated power consumption of the front end is less than 2 W. Finally, the Stage 2 computations are mapped onto a reconfigurable multi-core architecture, TRANSFORMER, which supports different types of on-chip memory banks and run-time reconfigurable connections between general processing elements and memory banks. The matched filtering step and the beamforming step in Stage 2 are mapped onto TRANSFORMER with different memory configurations. Gem5 simulations show that the private cache mode generates shorter execution time and higher computation efficiency compared to other cache modes. The overall execution time for Stage 2 is 14.73 ms. The average power consumption and the average Giga-operations-per-second/Watt in 14 nm technology node are 0.14 W and 103.84, respectively.Dissertation/ThesisDoctoral Dissertation Engineering 201

Architectural Support for Medical Imaging

Advancements in medical imaging research are continuously providing doctors with better diagnostic information, removing the need for unnecessary surgeries and increasing accuracy in predicting life-threatening conditions. However, newly developed techniques are currently limited by the capabilities of existing computer hardware, restricting them to expensive, custom-designed machines that only the largest hospital systems can afford or even worse, precluding them entirely. Many of these issues are due to existing hardware being ill-suited for these types of algorithms and not designed with medical imaging in mind. In this thesis we discuss our efforts to motivate and democratize architectural support for advanced medical imaging tasks with MIRAQLE, a medical image reconstruction benchmark suite. In particular, MIRAQLE focuses on advanced image reconstruction techniques for 3D ultrasound, low-dose X-ray CT, and dynamic MRI. For each imaging modality we provide a detailed background and parallel implementations to enable future hardware development. In addition to providing baseline algorithms for these workloads, we also develop a unique analysis tool that provides image quality feedback for each simulation. This allows hardware designers to explore acceptable image quality trade-offs in algorithm-hardware co-design, potentially allowing for even more efficient solutions than hardware innovations alone could provide. We also motivate the need for such tools by discussing Sonic Millip3De, our low-power, highly parallel hardware for 3D ultrasound. Using Sonic Millip3De, we illustrate the orders-of-magnitude power efficiency improvement that better medical imaging hardware can provide, especially when developed with a hardware-software co-design. We also show validation of the design using a scaled-down FPGA proof-of-concept and discuss our further refinement of the hardware to support a wider range of applications and produce higher frame rates. Overall, with this thesis we hope to enable application specific hardware support for the critical medical imaging tasks in MIRAQLE to make them practical for wide clinical use.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/137105/1/rsamp_1.pd

Cheetah: A Library for Parallel Ultrasound Beamforming in Multi -Core Systems

6 páginas, 2 figuras, 4 tablasDeveloping new imaging methods needs to establish some proofs of concept before implementing them on real -time scenarios. Nowadays, the high computational power reached by multi-core CPUs and GPUs have driven the development of software-based beamformers. Taking this into account, a library for the fast generation of ultrasound images is presented. It is based on Synthetic Aperture Imaging Techniques (SAFT) and it is fast because of the use of parallel computing techniques. Any kind of transducers as well as SAFT techniques can be defined although it includes some pre-built SAFT methods like 2R -SAFT and TFM. Furthermore, 2D and 3D imaging (slicebased or full volume computation) is supported along with the ability to generate both rectangular and angular images. For interpolation, linear and polynomial schemes can be chosen. The versatility of the library is ensured by interfacing it to Matlab, Python and any programming language over different operating systems. On a standard PC equipped with a single NVIDIA Quadro 4000 (256 cores), the library is able to calculate 262,144 pixels in ≈ 105 ms using a linear transducer with 64 elements, and 2,097,152 voxels in ≈ 5 seconds using a matrix transducer with 121 elements when TFM is applied.This work has been supported by the Spanish Government and the University of Alcalá under projects DPI2010- 19376 and CCG2014/EXP -084, respectively.Peer reviewe

Parallelization and improvement of beamforming process in synthetic aperture systems for real-time ultrasonic image generation

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Informática, Departamento de Arquitectura de Computadores y Automática, leída el 9-02-2016La ecografía es hoy en día uno de los métodos de visualización más populares para examinar el interior de cuerpos opacos. Su aplicación es especialmente significativa tanto en el campo del diagnóstico médico como en las aplicaciones de evaluación no destructiva en el ámbito industrial, donde se evalúa la integridad de un componente o una estructura. El desarrollo de sistemas ecográficos de alta calidad y con buenas prestaciones se basa en el empleo de sistemas multisensoriales conocidos como arrays que pueden estar compuestos por varias decenas de elementos. El desarrollo de estos dispositivos tiene asociada una elevada complejidad, tanto por el número de sensores y la electrónica necesaria para la adquisición paralela de señales, como por la etapa de procesamiento de los datos adquiridos que debe operar en tiempo real. Esta etapa de procesamiento de señal trabaja con un elevado flujo de datos en paralelo y desarrolla, además de la composición de imagen, otras sofisticadas técnicas de medidas sobre los datos (medida de elasticidad, flujo, etc). En este sentido, el desarrollo de nuevos sistemas de imagen con mayores prestaciones (resolución, rango dinámico, imagen 3D, etc) está fuertemente limitado por el número de canales en la apertura del array. Mientras algunos estudios se han centrado en la reducción activa de sensores (sparse arrays como ejemplo), otros se han centrado en analizar diferentes estrategias de adquisiciónn que, operando con un número reducido de canales electrónicos en paralelo, sean capaz por multiplexación emular el funcionamiento de una apertura plena. A estas últimas técnicas se las agrupa mediante el concepto de Técnicas de Apertura Sintética (SAFT). Su interés radica en que no solo son capaces de reducir los requerimientos hardware del sistema (bajo consumo, portabilidad, coste, etc) sino que además permiten dentro de cierto compromiso la mejora de la calidad de imagen respecto a los sistemas convencionales...Ultrasound is nowadays one of the most popular visualization methods to examine the interior of opaque objects. Its application is particularly significant in the field of medical diagnosis as well as non-destructive evaluation applications in industry. The development of high performance ultrasound imaging systems is based on the use of multisensory systems known as arrays, which may be composed by dozens of elements. The development of these devices has associated a high complexity, due to the number of sensors and electronics needed for the parallel acquisition of signals, and for the processing stage of the acquired data which must operate on real-time. This signal processing stage works with a high data flow in parallel and develops, besides the image composition, other sophisticated measure techniques (measure of elasticity, flow, etc). In this sense, the development of new imaging systems with higher performance (resolution, dynamic range, 3D imaging, etc) is strongly limited by the number of channels in array’s aperture. While some studies have been focused on the reduction of active sensors (i.e. sparse arrays), others have been centered on analysing different acquisition strategies which, operating with reduced number of electronic channels in parallel, are able to emulate by multiplexing the behavior of a full aperture. These latest techniques are grouped under the term known as Synthetic Aperture Techniques (SAFT). Their interest is that they are able to reduce hardware requirements (low power, portability, cost, etc) and also allow to improve the image quality over conventional systems...Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEunpu

Advancements and Breakthroughs in Ultrasound Imaging

Ultrasonic imaging is a powerful diagnostic tool available to medical practitioners, engineers and researchers today. Due to the relative safety, and the non-invasive nature, ultrasonic imaging has become one of the most rapidly advancing technologies. These rapid advances are directly related to the parallel advancements in electronics, computing, and transducer technology together with sophisticated signal processing techniques. This book focuses on state of the art developments in ultrasonic imaging applications and underlying technologies presented by leading practitioners and researchers from many parts of the world

Autoenfoque en imagen ultrasónica

La inspección de componentes por ultrasonidos se realiza, actualmente, con sistemas de imagen phased array, versión industrial de los ecógrafos médicos. En ambos casos se utiliza un array con decenas o centenares de pequeños transductores piezoeléctricos que se controlan individualmente para enfocar y deflectar el haz ultrasónico en emisión y recepción. Pero, mientras que en medicina el array está en contacto con el cuerpo, que es flexible, en la industria se suele interponer un medio acoplante entre el array y el componente a inspeccionar. Cuando la geometría de la pieza no es plana se utiliza agua como medio acoplante, que se adapta a la forma de la pieza y proporciona un medio continuo y de baja atenuación para la transmisión del sonido. En estas condiciones existen dos medios de propagación, lo que dificulta la determinación de los retardos de enfoque por efectos de la refracción. Como en estas condiciones no existen fórmulas cerradas que faciliten su cálculo, hasta la fecha se han venido utilizando procesos iterativos computacionalmente costosos que impiden la modificación rápida del enfoque cuando varía la geometría de la pieza (por ejemplo, durante la realización de un barrido). Estas razones han impedido el desarrollo de técnicas de autoenfoque efectivas. Esta Tesis aporta tres técnicas que, junto al cálculo en tiempo real de los parámetros de enfoque y un soporte arquitectural de imagen a ultra-alta velocidad, están entre las primeras aproximaciones reales para solucionar el problema del autoenfoque en imagen ultrasónica. De hecho, una de ellas (AUTOFOCUS) ha sido patentada y transferida a la industria, que la comercializa en equipos phased array con esta capacidad. La memoria describe las motivaciones, fundamentos, aproximaciones conocidas al problema así como las dificultades y las soluciones investigadas. Una segunda parte incluye las publicaciones más relevantes donde se han comunicado los resultados, contrastando los teóricamente esperados con los experimentalmente obtenidos