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.

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.

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.

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.