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Diagnostic ultrasound is non-invasive and provides real-time imaging. Microbubbles (MBs) are ultrasound contrast agents used to observe small blood flow, such as tumor tissue. ...However, MBs have short blood flow imaging time. This study developed lipid-based microbubbles (LMBs) with longer blood flow imaging time by focusing on their shell composition. Liposome research reported that addition 1,2-distearoyl-sn-glycero-3-phosphoglycerol (DSPG) to the lipid composition enhances liposome membrane stability. Therefore, we introduced DSPG at different ratios into the LMBs lipid shell. Results showed that the lipid shell composition of MBs affects stability in vivo. 60% DSPG-containing LMBs (DSPG60-LMBs) have sustained blood flow imaging time compared with LMBs, which have other DSPG ratios, Sonazoid® and SonoVue®. DSPG60-LMBs also showed less uptake into the liver compared with Sonazoid®. Therefore, DSPG60-LMBs can have long blood flow imaging time and can be effective diagnostic agents in ultrasound imaging.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Monitoring multiphase flow process and measuring its parameters have been a research topic that received broad attentions for the past decades. Ultrasonic process tomography (UPT) obtains the ...distribution of the two-phase flow based on ultrasound propagation in different fluids, making it valuable to the industrial monitoring and measurement. UPT can nonintrusively explore transient hydrodynamics of the multiphase flow, but the reconstruction quality of single modality is always dependent on phase distribution. In this paper, a dual-mode UPT that fuses the attenuation and time-of-flight of ultrasound is presented. To implement this scheme, a digital dual-mode UPT system that works under both the transmission-mode and reflection-mode is designed. A 16-channel ultrasound data acquisition system is proposed, which is flexibly programmable and reconfigurable through an field-programmable gate array (FPGA). The system includes a series of functional modules, and is based on the compact peripheral component interconnect bus for real-time data transmission to meet industrial field requirements. Static experiments show that the system can distinguish the interface of the different inclusions and preferably reconstruct the position and area of the inclusions through fusing the transmission and reflection reconstruction, the relative error and correlation coefficient of the reconstructed images are presented, respectively, which show preferable and stable distinguishability of different inclusions.
Purpose
To present and assess an outlier mitigation method that makes free‐running volumetric cardiovascular MRI (CMR) more robust to motion.
Methods
The proposed method, called compressive recovery ...with outlier rejection (CORe), models outliers in the measured data as an additive auxiliary variable. We enforce MR physics‐guided group sparsity on the auxiliary variable, and jointly estimate it along with the image using an iterative algorithm. For evaluation, CORe is first compared to traditional compressed sensing (CS), robust regression (RR), and an existing outlier rejection method using two simulation studies. Then, CORe is compared to CS using seven three‐dimensional (3D) cine, 12 rest four‐dimensional (4D) flow, and eight stress 4D flow imaging datasets.
Results
Our simulation studies show that CORe outperforms CS, RR, and the existing outlier rejection method in terms of normalized mean square error and structural similarity index across 55 different realizations. The expert reader evaluation of 3D cine images demonstrates that CORe is more effective in suppressing artifacts while maintaining or improving image sharpness. Finally, 4D flow images show that CORe yields more reliable and consistent flow measurements, especially in the presence of involuntary subject motion or exercise stress.
Conclusion
An outlier rejection method is presented and tested using simulated and measured data. This method can help suppress motion artifacts in a wide range of free‐running CMR applications.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Functional ultrasound imaging (fUS) recently emerged as a promising neuroimaging modality to image and monitor brain activity based on cerebral blood volume response (CBV) and neurovascular coupling. ...fUS offers very good spatial and temporal resolutions compared to fMRI gold standard as well as simplicity and portability. It was recently extended to 4D fUS imaging in preclinical settings although this approach remains limited and complex. Indeed 4D fUS requires a 2D matrix probe and specific hardware able to drive the N 2 elements of the probe with thousands of electronic channels. Several under-sampling approaches are currently investigated to limit the channel count and spread ultrasound 4D modalities. Among them, the Row Column Addressing (RCA) approach combined with ultrafast imaging is a compelling alternative using only N + N channels. We present a large field of view RCA probe prototype of 128 + 128 channels and 15 MHz central frequency adapted for preclinical imaging. Based on the Orthogonal Plane Wave compounding scheme, we were able to perform 4D vascular brain acquisitions at high volume rate. Doppler volumes of the whole rat brain were obtained in vivo at high rates (23 dB CNR at 156 Hz and 19 dB CNR at 313 Hz). Visual and whiskers stimulations were performed and the corresponding CBV increases were reconstructed in 3D with successful functional activation detected in the superior colliculus and somato-sensorial cortex respectively. This proof of concept study demonstrates for the first time the use of a low-channel count RCA array for in vivo 4D fUS imaging in the whole rat brain.
As new ultrasound flow imaging methods are being developed, there is a growing need to devise appropriate flow phantoms that can holistically assess the accuracy of the derived flow estimates. In ...this paper, we present a novel spiral flow phantom design whose Archimedean spiral lumen naturally gives rise to multi-directional flow over all possible angles (i.e., from 0° to 360°). Developed using lost-core casting principles, the phantom geometry comprised a three-loop spiral (4-mm diameter and 5-mm pitch), and it was set to operate in steady flow mode (3 mL/s flow rate). After characterizing the flow pattern within the spiral vessel using computational fluid dynamics (CFD) simulations, the phantom was applied to evaluate the performance of color flow imaging (CFI) and high-frame-rate vector flow imaging. Significant spurious coloring artifacts were found when using CFI to visualize flow in the spiral phantom. In contrast, using vector flow imaging (least-squares multi-angle Doppler based on a three-transmit and three-receive configuration), we observed consistent depiction of flow velocity magnitude and direction within the spiral vessel lumen. The spiral flow phantom was also found to be a useful tool in facilitating demonstration of dynamic flow visualization based on vector projectile imaging. Overall, these results demonstrate the spiral flow phantom's practical value in analyzing the efficacy of ultrasound flow estimation methods.
Ultrasound Vector Flow Imaging-Part I: Sequential Systems Jensen, Jorgen Arendt; Nikolov, Svetoslav Ivanov; Yu, Alfred C. H. ...
IEEE transactions on ultrasonics, ferroelectrics, and frequency control,
2016-Nov., 2016-11-00, 20161101, Volume:
63, Issue:
11
Journal Article
Peer reviewed
Open access
This paper gives a review of the most important methods for blood velocity vector flow imaging (VFI) for conventional sequential data acquisition. This includes multibeam methods, speckle tracking, ...transverse oscillation, color flow mapping derived VFI, directional beamforming, and variants of these. The review covers both 2-D and 3-D velocity estimation and gives a historical perspective on the development along with a summary of various vector flow visualization algorithms. The current state of the art is explained along with an overview of clinical studies conducted and methods for presenting and using VFI. A number of examples of VFI images are presented, and the current limitations and potential solutions are discussed.
Eigen-filters with attenuation response adapted to clutter statistics in color flow imaging (CFI) have shown improved flow detection sensitivity in the presence of tissue motion. Nevertheless, its ...practical adoption in clinical use is not straightforward due to the high computational cost for solving eigendecompositions. Here, we provide a pedagogical description of how a real-time computing framework for eigen-based clutter filtering can be developed through a single-instruction, multiple data (SIMD) computing approach that can be implemented on a graphical processing unit (GPU). Emphasis is placed on the single-ensemble-based eigen-filtering approach (Hankel singular value decomposition), since it is algorithmically compatible with GPU-based SIMD computing. The key algebraic principles and the corresponding SIMD algorithm are explained, and annotations on how such algorithm can be rationally implemented on the GPU are presented. Real-time efficacy of our framework was experimentally investigated on a single GPU device (GTX Titan X), and the computing throughput for varying scan depths and slow-time ensemble lengths was studied. Using our eigen-processing framework, real-time video-range throughput (24 frames/s) can be attained for CFI frames with full view in azimuth direction (128 scanlines), up to a scan depth of 5 cm (\lambda pixel axial spacing) for slow-time ensemble length of 16 samples. The corresponding CFI image frames, with respect to the ones derived from non-adaptive polynomial regression clutter filtering, yielded enhanced flow detection sensitivity in vivo, as demonstrated in a carotid imaging case example. These findings indicate that the GPU-enabled eigen-based clutter filtering can improve CFI flow detection performance in real time.
This study aimed to assess the feasibility and usefulness of transabdominal color Doppler flow imaging(CDFI)technology and the high-definition flow imaging(HDFI)technique in detecting fetal pulmonary ...veins(PVs)in the first trimester(11-13+6 weeks).Methods:From December 2018 to October 2019,328 pregnant women with 328 normal singleton fetuses(crown-rump length:45-84 mm)who had undergone CDFI and HDFI scans for fetal heart and vessel examination were enrolled in this study.The cases were divided into three groups according to the gestational age:group A,11+0-11+6 weeks;group B,12+0-12+6 weeks;and group C,13+0-13+6 weeks.Baseline sonograms and CDFI and HDFI images were analyzed by two senior radiologists independently and blindly.The abilities of CDFI and HDFI to display PVs were compared.Results:Successful PV display rates via CDFI and HDFI were 2.3％and 68.2％(P＜0.01),22.4％and 82.4％(P＜0.01),41.5％and 91.2％(P＜0.01)for group A,group B,and group C,respectively.The total successful display rates for the two methods were 28.9％(CDFI)and 84.8％(HDFI)(P＜0.01).Conclusions:The HDFI technique is more valuable than CDFI for detecting PVs in early pregnancy(11-13+6 weeks).HDFI can detect at least one PV in all cases and may be used to detect pulmonary venous anomalies early.
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•A new multi-probe flow profiler designed for distillation trays is proposed.•The profiler essentials and data processing techniques are discussed in detail.•3D distribution of liquid ...holdup above the deck is evaluated in high resolution.•Liquid flow in the two-phase dispersion above the deck is monitored via tracer.•Non-uniform holdup distribution is observed along the dispersion height.•Liquid flow is reasonably uniform with symmetry across the tray centerline.
A profound knowledge of the two-phase cross-flow on large-scale distillation trays is pivotal to their efficient design and operation. For such trays, a novel flow profiler comprising of multiple dual-tip probes for simultaneous local conductivity measurements is proposed in this work. The profiler is applied for a DN800 air/water column simulator equipped with sieve trays. 3D distribution of liquid holdup and tracer-based liquid flow in the two-phase dispersion are assessed in high resolution. Non-uniform holdup is found along the dispersion height. Contrarily, the liquid flow is largely uniform and symmetric with respect to the tray centerline. Prior to measurements, the profiler design, electronic scheme, measurement principle and data processing schemes are described.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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