A Joint Delay-and-Sum and Fourier Beamforming Method for High Frame Rate Ultrasound Imaging

Frame rate is an important metric for ultrasound imaging systems,and high frame rates(HFR)benefit moving-target imaging.One common way to obtain HFR imaging is to transmit a plane wave.Delay-and-sum(DAS)beamformer is a conventional beamforming algorithm,which is simple and has been widely implemented in clinical application.Fourier beamforming is an alternative method for HFR imaging and has high levels of imaging efficiency,imaging speed,and good temporal dynamic characteristics.Nevertheless,the resolution and contrast performance of HFR imaging based on DAS or Fourier beamforming are insufficient due to the single plane wave transmission.To address this problem,a joint DAS and Fourier beamforming method is introduced in this study.The proposed method considers the different distributions of sidelobes in DAS imaging and Fourier imaging and combines the angular spectrum and DAS to reconstruct ultrasound images.The proposed method is evaluated on simulation and experimental phantom datasets to compare its performance with DAS and Fourier beamforming methods.Results demonstrate that the proposed method improves image effective dynamic range and resolution while also retaining a high frame rate of the ultrasound imaging systems.The proposed method improves the effective dynamic range along axial and lateral directions by 10 dB,compared to standard DAS and Fourier beamforming.

An Efficient Algorithm Based on Spectrum Migration for High Frame Rate Ultrasound Imaging

The high frame rate(HFR)imaging technique requires only one emission event for imaging.Therefore,it can achieve ultrafast imaging with frame rates up to the kHz regime,which satisfies the frame rate requirements for imaging moving tissues in scientific research and clinics.Lu’s Fourier migration method is based on a non-diffraction beam to obtain HFR images and can improve computational speed and efficiency.However,in order to obtain high-quality images,Fourier migration needs to make full use of the spectrum of echo signals for imaging,which requires a large number of Fast Fourier Transform(FFT)points and increases the complexity of the hardware when the echo frequency is high.Here,an efficient algorithm using the spectrum migration technique based on the spectrum’s distribution characteristics is proposed to improve the imaging efficiency in HFR imaging.Since the actual echo signal spectrum is of limited bandwidth,low-frequency and high-frequency parts with low-energy have little contribution to the imaging spectrum.We transform the effective part that provides the main energy in the signal spectrum to the imaging spectrum while the ineffective spectrum components are not utilized for imaging.This can significantly reduce the number of Fourier transform points,improve Fourier imaging efficiency,and ensure the imaging quality.The proposed method is evaluated on simulated and experimental datasets.Results demonstrated that the proposed method could achieve equivalent image quality with a reduced point number for FFT compared to the complete spectrum migration.In this paper,it only requires a quarter of the FFT points used in the complete spectrum migration,which can improve the computational efficiency;thus,it is more suitable for real-time data processing.The proposed spectrum migration method has a specific significance for the study and clinical application of HFR imaging.

High Frame Rate Contrast-enhanced Ultrasound Helps Differentiate Malignant and Benign Focal Liver Lesions

Background and Aims:This study aimed to evaluate the diagnostic performance of high frame rate contrast-en-hanced ultrasound(H-CEUS)of focal liver lesions(FLLs).Methods:From July 2017 to June 2019,conventional con-trast-enhanced ultrasound(C-CEUS)and H-CEUS were per-formed in 78 patients with 78 nodules.The characteristics of C-CEUS and H-CEUS in malignant and benign groups and the differences between different lesion sizes(1-3 cm,3-5 cm,or>5 cm)of C-CEUS and H-CEUS were examined.The diagnostic performance of C-CEUS and H-CEUS was ana-lyzed.The chi-square test or Fisher’s exact test was used to assess inter-group differences.The receiver operating characteristic curve was plotted to determine the diagnostic performance of C-CEUS and H-CEUS.Results:There were significant differences in the enhancement area,fill-in direc-tion and vascular architecture between C-CEUS and H-CEUS for both benign and malignant lesions(all p=0.000-0.008),but there were no significant differences in washout results(p=0.566 and p=0.684,respectively).For lesions 1-3 cm in size,the enhancement area,fill-in direction,and vascular architecture on C-CEUS and H-CEUS were significantly dif-ferent(all p=0.000),unlike for lesions 3-5 cm or>5 cm in size.For differentiation of malignant from benign FLLs in the 1-3 cm group,H-CEUS showed sensitivity,specific-ity,accuracy,and positive and negative predictive values of 92.86%,95.0%,96.3%,90.48%and 93.75%,respectively,which were higher than those for C-CEUS(75.0%,70.0%,77.78%,66.67%and 72.91%,respectively).Conclusions:H-CEUS provided more vascular information which could help differentiate malignant from benign FLLs,especially for lesions 1-3 cm in size.

Design of a very high frame rate camera based on an asynchronous CCD driving method

A very high frame rate camera is designed based on an innovative CCD driving method. The CCD driving method is mainly implemented on frame transfer CCDs. Asynchronous drive timing sequences are applied in the image and storage section of the CCDs. Several rows of the charge in the image section are binned onto the same row in the storage section, and there are the same number of images to be stored in the storage section before they are read out. Based on the new driving method, the frame transfer CCDs can work at a very high frame rate in acquiring burst images though the reading speed remains at a lower level. A very high frame rate camera is designed in this paper. The innovative CCD driving method is mainly of concern. An e2v’s CCD60 is adopted in the camera system, whose full size resolution is 128×128, and the up most frame rate is 1000 Hz in the conventional CCD driving method. By using the presented method, the CCD60 based imager is capable of operating at up to 40000 frames per second （fps） at a recognizable resolution of 128×32. Comparing cameras using traditional binning and region of interest technologies, the frame rate is normally less than 5000 fps while the resolution is only 32×32 left.

High-frame-rate contrast-enhanced ultrasound findings of liver metastasis of duodenal gastrointestinal stromal tumor:A case report and literature review

BACKGROUND Liver metastasis of duodenal gastrointestinal stromal tumor(GIST)is rare.Most reports mainly focus on its treatment and approaches to surgical resection,while details on its contrast-enhanced ultrasound(CEUS)findings are lacking.The diagnosis and imaging modalities for this condition remain challenging.CASE SUMMARY A 53-year-old Chinese man presented with mild signs and symptoms of the digestive tract.He underwent routine examinations after GIST surgery.Magnetic resonance imaging showed a 2.3 cm hepatic space-occupying lesion.All the laboratory test results were within normal limits.For further diagnostic confirmation,we conducted high frame rate CEUS(H-CEUS)and found a malignant perfusion pattern.Heterogeneous concentric hyper-enhancement,earlier wash-in than the liver parenchyma,and two irregular vessel columns could be observed at the periphery of the lesion during the arterial phase.Ultrasound-guided puncture biopsy was used to confirm the diagnosis of the lesion as liver metastasis of duodenal GIST.Imatinib was prescribed after biopsy,and the patient’s clinical course was monitored.CONCLUSION H-CEUS is useful for detecting microcirculation differences,wash-in patterns,and vascular morphogenesis and diagnosing liver metastasis of duodenal GIST.

100 Hertz frame-rate switching threedimensional orbital angular momentum multiplexing holography via cross convolution

The orbital angular momentum(OAM)of light has been implemented as an information carrier in OAM holography.Holographic information can be multiplexed in theoretical unbounded OAM channels,promoting the applications of optically addressable dynamic display and high-security optical encryption.However,the frame-rate of the dynamic extraction of the information reconstruction process in OAM holography is physically determined by the switching speed of the incident OAM states,which is currently below 30 Hz limited by refreshing rate of the phase-modulation spatial light modulator(SLM).Here,based on a cross convolution with the spatial frequency of the OAM-multiplexing hologram,the spatial frequencies of an elaborately-designed amplitude distribution,namely amplitude decoding key,has been adopted for the extraction of three-dimensional holographic information encoded in a specific OAM information channel.We experimentally demonstrated a dynamic extraction frame rate of 100 Hz from an OAM multiplexing hologram with 10 information channels indicated by individual OAM values from-50 to 50.The new concept of cross convolution theorem can even provide the potential of parallel reproduction and distribution of information encoded in many OAM channels at various positions which boosts the capacity of information processing far beyond the traditional decoding methods.Thus,our results provide a holographic paradigm for high-speed 3D information processing,paving an unprecedented way to achieve the high-capacity short-range optical communication system.

基于FPGA的高速大面阵成像系统设计

为了获取高帧频大面阵图像数据,设计了一套基于FPGA结合CMOS图像探测器的成像系统。首先,介绍了国产GSENSE6060图像探测器的特性和设计方法。然后提出了成像系统的供电等硬件设计。最后,重点研究了基于Xilinx公司Virtex-5型FPGA的CMOS图像数据训练算法,保证了数据采集的准确性。试验结果表明,所设计的成像系统在6 144 pixel×6 144 pixel分辨率时,帧频达20 frame/s,图像数据峰值速率16 Gbit/s,且读出噪声优于4e^(-)。目前,系统已经工程应用,其功能、性能满足了项目实际需要。

面向高帧率CMOS图像传感器的12位列级全差分SAR/SS ADC设计

针对高帧率CMOS图像传感器的应用需求,提出一种结合逐次逼近型(Successive Approximation Register,SAR)和单斜坡(Single Slope,SS)结构的混合型模拟数字转换器(Analog to Digital Converter,ADC)。该ADC的分辨率为12位,其中SAR ADC实现高6位量化,SS ADC实现低6位量化。该ADC采用了全差分结构消除采样开关的固定失调并减少非线性误差,同时在SAR ADC中采用了异步逻辑电路进一步缩短转换周期。采用110 nm 1P4M CMOS工艺对该电路进行了设计和版图实现,后仿真结果表明,在20 MHz的时钟下,转换周期仅为3.3μs,无杂散动态范围为77.12 dB,信噪失真比为67.38 dB,有效位数为10.90位。

高帧率超声造影定性特征联合定量参数鉴别前列腺良恶性疾病的应用价值

目的:探讨高帧率超声造影(high frame rate contrast-enhanced ultrasound,H-CEUS)定性特征联合定量参数对前列腺良恶性疾病的鉴别诊断价值。方法:选取2022年02月至2023年01月在我院就诊疑似前列腺癌(prostate cancer,PCa)并进行前列腺穿刺活检的患者60例(共67个病灶),根据病理结果分为良性组和恶性组,穿刺前行经直肠常规超声及H-CEUS,记录前列腺基本情况、造影定性特征并绘制时间强度曲线获得定量分析参数,比较两组间差异;以病理结果为“金标准”绘制受试者工作特征(receiver operating characteristic,ROC)曲线,应用Z检验比较H-CEUS定性特征、定量参数单独及联合应用对于前列腺病变良恶性的诊断效能。结果:与良性组相比,恶性组H-CEUS定性特征为供血动脉形态不规则(1/33 vs 11/34)及走形异常(3/33 vs 20/34)、快进(9/33 vs 29/34)、高增强(4/33 vs 25/34)、造影剂分布不均匀(9/33 vs 13/34)的比例较大,差异具有统计学意义(χ2=30.41、18.37、22.96、25.72、8.06,P<0.001、<0.001、<0.001、<0.001、=0.005);定量参数PCa较良性组造影到达时间早[(16.93±3.69)s vs(21.54±3.86)s],峰值强度[(48.8±5.58)dB vs(45.77±4.42)dB]、强度差[4.87(0.87,8.03)vs-0.44(-2.22,2.35)]及强度比[(1.15±0.24)vs(1.01±0.97)]的值较良性大,差异具有统计学意义(t/U=4.24、-2.324、151、-2.535,P<0.001、=0.025、=0.004、=0.015)。ROC曲线示H-CEUS定性及定量联合应用的AUC=0.938,截断值为0.44时诊断效能最佳,约登指数、敏感度、特异度、准确度、阳性预测值及阴性预测值为0.750、89.29%、85.71%、87.75%、89.3%、85.7%。根据净重新分类指数NRI值,联合应用对定性特征及定量参数均为正改善(P<0.05)。结论:H-CEUS应用于前列腺有助于观察造影灌注细节、分析成像特征,对于前列腺良恶性疾病具有较好的鉴别诊断能力,将造影灌注定性特征与定量参数结合的诊断效能优于单独应用。

一种高帧频大动态范围像素级数字化读出电路设计

与短波和中波器件相比,长波红外探测器具有较大的光电流和暗电流,故需要强大的电荷存储能力。而使用传统的模拟像元读出电路技术会严重受限于电荷存储能力,使得长波探测器的动态范围和信噪比难以提升,从而制约着长波红外成像系统的发展和应用。提出一种像素级数字读出电路技术,通过数字积分克服了传统模拟积分方案电荷存储能力受限的缺陷,实现了探测器的数字信号输出,能够极大提高探测器的动态范围、抗干扰能力和帧频。该技术是提升长波探测器性能的有效途径。基于该技术设计了一款像元间距为30 m的320×256数字读出电路,其输出以低压差分信号(Low Voltage Differential Signal,LVDS)方式传输。仿真结果显示,该电路的最高帧频可达1000 Hz,动态范围大于95 dB。

数字电影中“超真实”景观的建构与生存论解读

电影艺术是科技发展到一定阶段的产物,随着数字技术的全面介入,电影从生产到传播的各个环节都在发生变化。在今天,越来越多的电影创作者用数字技术开拓电影的表达边界。其中高帧率作为最具代表性的数字技术之一,使观众在银幕上获得了更深刻的沉浸式体验,成为数字电影构建“超真实”景观的主要技术手段。“超真实”景观的视觉神话满足了消费需求,而电影作为艺术的主体性使它依然需要观照人的生存境遇。因此数字技术的引入,使电影的“超真实”传递出一种对技术伦理的思考,以及对人存在的反思和对电影物质性的探索。

高帧频面探测器分布式数据获取软件研究

高帧频面探测器是上海硬X射线自由电子激光装置(Shanghai HIgh repetitioN rate xfel and Extreme light facility,SHINE)上主要成像类实验站的核心探测器,其预计数据通量将达到20 GB·s^(-1)以上。对于几十GB·s^(-1)原始数据流的实时接收和处理,传统单机系统很难应对。本文提出了一种多节点分布式面探测器数据获取和处理软件架构。首先,研究了不同网络库的性能,采用同步传输和CPU线程绑定等方法实现了接近3 GB·s^(-1)的单线程数据接收速率;依据X射线脉冲编号(Bunch ID)进行各模块数据的多节点分发与合并,采用4个节点实现了约23.5 GB·s^(-1)的并行事例重建速率;进一步,对数据刻度和压缩算法进行了实现和测试,结合bitshuffle和LZ4压缩算法,实现了约5.7倍的压缩率。本文验证了多节点分布式的并行数据获取方法的可行性,为后续面探测器高通量数据获取软件的开发打下基础。

视频合成孔径雷达技术发展现状综述

视频合成孔径雷达(video synthetic aperture radar,ViSAR)由于能够连续观测目标区域的变化,在许多领域得到了广泛的应用。首先梳理了国内外ViSAR相关的研究动态,分析了ViSAR高帧率成像以及动目标阴影形成的原理;然后系统地阐述了国内外ViSAR系统及其处理技术的研究进展,对成像算法、运动补偿算法以及动目标检测与跟踪技术等方面的研究进展进行了梳理和总结;最后总结了目前ViSAR相关的发展,并对未来ViSAR技术的潜在研究方向进行了展望。

一种新型高动态范围CMOS图像传感器结构设计

阐述一种新型的高动态范围CMOS图像传感器结构。在新型CMOS图像传感器中,像素包括两个具有不同感光灵敏度的光电二极管以及多个电荷-电压转换增益档位,列电路具有多个模拟电压增益档位。根据该结构和读出方法,对每个像素只进行一次信号电压的读取,可以显著缩短行读出时间,进而提高帧率。

超高清视频技术要素主观评价研究

本文研究了超高清视频技术要素对主观体验的影响,通过主观评价实验量化了分辨率、动态范围、帧率和量化深度等技术要素的提升对观看体验的贡献。实验结果显示,技术要素的提升对改善主观体验有积极作用,其中,4K分辨率、HDR技术、高帧率对主观体验的影响较为显著,2K HDR在某些情况下优于4K SDR。该研究为超高清视频技术的发展提供了参考。

利用国产FPGA的高帧率目标跟踪方法

由于复杂度较高的跟踪算法多数采用国外芯片实现,基于国产FPGA的跟踪方法得到了研究。针对易于FPGA设计的模板匹配算法鲁棒性不足的问题,基于绝对差和(SAD)相似性度量方法,提出了求窗口内最小绝对差和(SMAD)的方法。利用最大值和最小值滤波预先处理窗口内图像数据,再求最小绝对差,将SMAD算法的加减法器资源消耗降低为原来的31.8%。提出的类金字塔的方法在节省逻辑资源的同时,提高了对目标尺度变化的适应性。OTB数据集的实验表明:提出的方法与鲁棒性较高的DDIS算法相比,跟踪成功率和平均重叠率分别提高了1.18%、0.13%,又有易于流水线设计的优势。利用国产FPGA实现了帧率可达100 fps的实验系统并验证其跟踪性能,为在国产FPGA上实现高帧率目标跟踪系统提供了解决方案。

用于高速碰撞过程拍摄的5万帧摄像系统设计

为了近距离清晰拍摄某高速运动目标的碰撞过程,研究了一种高帧频摄像系统。由于摄像系统的前端可能遭受碰撞碎片的损坏,研究了一种保护窗组件。针对成像单元的FPGA在极端高温+70℃时温度过高的问题,研究了一种导热装置。采用七组成像单元在顺序脉冲的控制下接续拍摄的方法,实现了5万帧/秒的高帧频成像。保护窗组件采用了三组保护窗玻璃自动移动更换且可自锁的形式,采用蜗轮蜗杆传动机构实现了大传动比驱动和自锁功能,采用霍尔传感器对保护窗的位置进行实时反馈。导热装置中间部分采用了柔性的高热导率石墨板,既有效地将FPGA的热量传导至主壳体上,又解决了装调节环节中刚性导热装置的过定位问题。对装配好的高帧频摄像系统进行了相关的力、热实验。实验结果表明,保护窗组件自锁和移动切换功能正常,高帧频摄像工作正常,实测拍摄帧频为50 050帧/秒,满足近距离清晰拍摄某高速运动目标碰撞过程的要求,具备一定的防护能力和热环境适应能力。

基于相移轮廓术的双采样运动物体三维重构

相移轮廓术因其高精度和高鲁棒性广泛应用于三维重构。由于需投射多幅条纹图到物体表面,相移轮廓术要求物体在重构过程中保持静止,导致运动物体的三维重构精度较低。文中提出了一种基于相移轮廓术的双采样运动物体三维重构方法。首先调整相机和投影仪时序,使投影仪投射一幅条纹图的同时,相机完成两次采集。然后分析物体运动对双采样条纹图的影响,并建立条纹描述方程。结合物体的运动信息,提取混合相移条纹图中的相位信息。最终对拍摄条纹图进行复用,提高运动物体的三维重构帧率。实验结果表明,该方法不仅可以精确重构运动物体,减少运动误差,还在投影速度受限的前提下提高了运动物体的三维重构帧率。

高帧率超声造影在鉴别浅表淋巴结良恶性中的临床价值

目的应用高帧率超声造影观察浅表淋巴结增强均匀性和灌注方向,探讨其鉴别良恶性淋巴结的临床价值。方法选取我院经病理证实的浅表淋巴结异常患者121例(共121枚淋巴结),根据淋巴结大小分为A组37例(最大径0.5~1.0 cm)、B组56例(最大径>1.0~2.0 cm)、C组28例(最大径>2.0 cm),均行常规帧率及高帧率超声造影并保留其对应的动脉期图像,然后启动微血流增强模式,以1/3~1/2倍速播放并留存动态图像,分析两种造影帧率下各组良恶性浅表淋巴结增强均匀性和灌注方向的差异。绘制受试者工作特征(ROC)曲线分析常规帧率及高帧率超声造影鉴别不同大小良恶性浅表淋巴结的诊断效能。结果常规帧率和高帧率超声造影显示121例良恶性浅表淋巴结增强均匀性比较差异均有统计学意义(均χ^(2)=14.546,均P<0.001);常规帧率和高帧率超声造影显示良恶性浅表淋巴结灌注方向比较差异均有统计学意义(χ^(2)=5.160、4.600,均P<0.05)。C组中良恶性浅表淋巴结增强均匀性比较差异有统计学意义(χ^(2)=9.614,P=0.002)。各组中良恶性浅表淋巴结灌注方向比较差异均有统计学意义(均P<0.05)。ROC曲线分析显示,高帧率超声造影及常规帧率超声造影鉴别良恶性浅表淋巴结的曲线下面积(AUC)均分别为0.852、0.740,差异有统计学意义(Z=2.640,P=0.008);其中A、B、C组高帧率超声造影与常规帧率超声造影鉴别良恶性浅表淋巴结的AUC分别为0.817和0.669、0.864和0.732、0.827和0.772。A组两种帧率超声造影的AUC比较差异有统计学意义(Z=2.101,P=0.036),B、C组两种帧率超声造影的AUC比较差异均无统计学意义(Z=1.509、0.797,P=0.131、0.425)。结论高帧率超声造影可以清晰显示良恶性浅表淋巴结的增强均匀性和灌注方向,具有较好的鉴别诊断价值。

高帧率剪切波评价血液透析患者冈上肌腱的力学性能

目的基于高帧率剪切波(high frame rate sound touch elastography,HiFR STE)评价血液透析患者冈上肌腱的力学性能。方法选取汕头大学医学院第一附属医院规律血液透析的患者46例和健康志愿者23例。通过透析龄中位数(74.5个月)将血液透析患者分为透析龄较短组[49.00(14.00,69.00)]和透析龄较长组[91.00(78.00,122.00)]。使用迈瑞Resona R9 Pro超声诊断仪及L15-3Wu线阵探头进行二维超声和HiFR STE成像,测量并比较不同透析龄的血液透析患者和健康对照组的冈上肌腱厚度及杨氏模量平均值(the mean of Young s modulus,Emean)的差异,并观察各组间肩关节的骨质破坏、滑膜增厚及关节积液常规声像特征。结果健康对照组、透析龄较短组及透析龄较长组的冈上肌腱厚度和Emean值在3组间差异有统计学意义(P<0.001),冈上肌腱厚度分别为(5.73±0.70)mm、(6.57±0.93)mm和(6.80±0.84)mm,两两比较结果显示不同透析龄的血液透析患者冈上肌腱厚度均高于对照组(P<0.05);HiFR STE测得3组的冈上肌腱Emean值分别为(61.27±21.64)kPa、(42.56±25.30)kPa和(31.13±17.40)kPa,两两比较结果显示不同透析龄的血液透析患者冈上肌腱Emean值均低于对照组(P<0.05);骨侵蚀率及滑膜增厚率在3组间的差异具有统计学意义(P<0.05)。结论血液透析患者的冈上肌腱增厚及出现力学性能下降。基于HiFR STE技术测得的Emean对血液透析患者冈上肌腱的力学性能进行定量评估,可为临床筛选肩袖撕裂的潜在风险人群提供客观依据。