High-Level Synthesis Design of Scalable Ultrafast Ultrasound Beamformer With Single FPGA.
High-Level Synthesis Design of Scalable Ultrafast Ultrasound Beamformer With Single FPGA.
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DOI：
10.1109/tbcas.2023.3267614
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发表时间：
2023-06
影响因子：
5.1
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超快超声成像是超声定位显微镜(ULM)和功能超声(FUS)等先进超声成像技术的基础。当前的超快超声成像受到与射频(RF)信号相关的超高数据带宽以及计算昂贵的波束形成过程的延迟的挑战。因此，使用现有的基于CPU或GPU的软件波束形成器，连续的超高速数据采集和波束形成仍然难以实现。为了应对这些挑战，提出了一种新的方法，通过高层综合在现场可编程门阵列(FPGA)上实现了专门用于超快平面波成像(PWI)的超快超声波束形成器。提出了一种波束形成器在单片现场可编程门阵列上的并行化实现方法：1)采用延迟压缩技术减小延时分布尺寸，实现从外部存储器加载运行时预先计算的延时分布和延时重用；2)通过延时重用实现通道数据获取的矢量化；3)使用固定求和网络减少逻辑资源的消耗。与现有的FPGA波束形成器相比，我们提出的方法具有两个独特的优点：1)高可扩展性，通过使用Xilinx高级综合作为开发工具，可以快速适应不同的FPGA资源和波束形成速度要求；2)通过使用单个FPGA来完成波束形成，而不是使用多个FPGA来实现紧凑的形状因数设计。目前的Xilinx公司的现场可编程门阵列能够通过单片现场可编程门阵列和最新的JESD204B接口模拟前端(AFE)连接多达1024个超声通道。该通道数比当前线性阵列所需的通道数多得多，当前线性阵列通常具有128或256个通道。该方法以输入原始射频样本为例，获得了4.83G样本/秒的可持续平均波束形成速率。将所提出的波束形成器的结果图像质量与Verasonics Vantage系统上的软件波束形成器进行了比较，以进行小鼠大脑的体模成像和活体成像。评估了包括B超、能量多普勒和ULM在内的多种成像方案，以验证图像质量没有受到速度的影响。
Ultrafast ultrasound imaging is essential for advanced ultrasound imaging techniques such as ultrasound localization microscopy (ULM) and functional ultrasound (fUS). Current ultrafast ultrasound imaging is challenged by the ultrahigh data bandwidth associated with the radio frequency (RF) signal, and by the latency of the computationally expensive beamforming process. As such, continuous ultrafast data acquisition and beamforming remain elusive with existing software beamformers based on CPUs or GPUs. To address these challenges, the proposed work introduces a novel method of implementing an ultrafast ultrasound beamformer specifically for ultrafast plane wave imaging (PWI) on a field programmable gate array (FPGA) by using high-level synthesis. A parallelized implementation of the beamformer on a single FPGA was proposed by 1) utilizing a delay compression technique to reduce the delay profile size, which enables both run-time pre-calculated delay profile loading from external memory and delay reuse, 2) vectorizing channel data fetching which is enabled by delay reuse, and 3) using fixed summing networks to reduce consumption of logic resources. Our proposed method presents two unique advantages over current FPGA beamformers: 1) high scalability that allows fast adaptation to different FPGA resources and beamforming speed demands by using Xilinx High-Level Synthesis as the development tool, and 2) allow a compact form factor design by using a single FPGA to complete the beamforming instead of multiple FPGAs. Current Xilinx FPGAs provide the capabilities of connecting up to 1024 ultrasound channels with a single FPGA and the newest JESD204B interface analog front end (AFE). This channel count is much more than the channel count needed by current linear arrays, which normally have 128 or 256 channels. With the proposed method, a sustainable average beamforming rate of 4.83 G samples/second in terms of input raw RF sample was achieved. The resulting image quality of the proposed beamformer was compared with the software beamformer on the Verasonics Vantage system for both phantom imaging and in vivo imaging of a mouse brain. Multiple imaging schemes including B-mode, power Doppler and ULM were assessed to verify that the image quality was not compromised for speed.