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[IEEE 2018 Joint Conference - Acoustics - Ustka, Poland (2018.9.11-2018.9.14)] 2018 Joint Conference - Acoustics - Crosstalk Effect in Medical Ultrasound Tomography Imaging
摘要： Ultrasound tomography (UT) is a modern method of medical imaging that has been intensively developed recently to diagnose female breasts in vivo. This method makes it possible to acquire images in various ultrasound modalities simultaneously - both transmission and reflection ones, without any focusing. Therefore, the ultrasound intensity level when scanning individual coronal breast sections is relatively low. Data for reconstruction of images is obtained by means of a multi-element array of small piezoceramic transducers spaced evenly on the inner side of the ring surrounding the breast immersed in water. The main problem with such arrangements is the occurrence of crosstalk, which introduces specific errors to measurement data. Crosstalk is a result of a deficiency in electrical or mechanical isolation between array elements. Such errors lead to distortions in the reconstructed images. In the paper, the effect of crosstalk in the ultrasound tomography ring array was examined and analyzed. The influence of crosstalk on the reconstructed images of the breast structure was shown as well. Conducted studies enabled the detection of the sources and paths of crosstalk and, as a consequence, it allowed us to improve the design of the multi-element ultrasonic transducer ring array, and to reduce crosstalk.
关键词： medical imaging,ultrasound tomography method,breast diagnosis,crosstalk effect
更新于2025-09-23 15:21:21
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Functionalized Holmium-Doped Hollow Silica Nanospheres for Combined Sonodynamic and Hypoxia-Activated Therapy
摘要： The oxygen concentration dependence of sonodynamic therapy (SDT) and bioreductive therapy can be utilized to design the strategy of synergistic therapy. Herein, holmium-doped hollow silica nanospheres are synthesized and then sequentially modified with chlorin e6, carboxyl poly(ethylene glycol) silane, and prostate stem cell antigen (PSCA) monoclonal antibody. The resultant nanocomposite designated as HHSN-C/P-mAb has good biocompatibility and can specifically target cancer cells overexpressing PSCA. Due to the inner cavity structure and Ho doping, HHSN-C/P-mAb shows high ultrasound (US) imaging contrast capability and excellent high-field magnetic resonance contrast performance. HHSN-C/P-mAb can act as a nanocarrier for loading the bioreductive prodrug tirapazamine (TPZ), and the degradation of the hollow nanospheres under the trigger of acidic microenvironment favors the pH responsive release of TPZ from the material. Upon US irradiation, HHSN-C/P-mAb produces reactive oxygen species to kill the cancer cells, and importantly, the oxygen consumption during SDT induces an intratumoral hypoxic environment to activate the therapeutic function of codelivered TPZ, resulting in a high-effective synergistic therapy. The findings of this study highlight that HHSN-C/P-mAb is a versatile theranostic nanoplatform for efficient cancer treatment.
关键词： magnetic resonance imaging,sonodynamic therapy,ultrasound imaging,holmium-doped hollow silica nanosphere,bioreductive therapy
更新于2025-09-23 15:21:21
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Improving Spatial Resolution Using Incoherent Subtraction of Receive Beams Having Different Apodizations
摘要： In ultrasonic imaging, reduction of lateral sidelobes can result in an improved image with less distortion and fewer artifacts. In general, apodization is used to lower sidelobes in exchange for increasing the width of the mainlobe and thus decreasing lateral resolution. Null subtraction imaging (NSI) is a nonlinear image processing technique that uses different receive apodizations on copies of the same RF data to maintain low sidelobe levels while simultaneously improving lateral resolution. The images created with three different apodization functions are combined to form an image with low sidelobe levels and apparent improvements in lateral resolution compared to conventional rectangular apodization. To evaluate the performance of this technique for different imaging tasks, experiments were performed on an ATS539 phantom containing wire targets to assess lateral resolution and cylindrical anechoic and hyperechoic targets to assess contrast. NSI images were compared against rectangular apodized images and minimum variance (MV) beamformed images. In experiments, the apparent lateral resolution was observed to improve by a factor of more than 35 times when compared to rectangular apodization. Image quality was assessed by estimation of lateral resolution (-6-dB receive beamwidth), mainlobe to sidelobe ratio (MSR) and contrast-to-noise ratio (CNR). Imaging with NSI using a focal number of 2 (f/2), the -6-dB beamwidth on receive as measured from a small wire target in the ATS phantom was 0.03λ compared to 2.79λ for rectangular apodization. Sidelobes were observed to decrease by 32.9 dB with NSI compared to rectangular apodization. However, the ability to observe the contrast of anechoic and hyperechoic targets reduced when utilizing the NSI scheme, i.e., the CNR decreased from -3.05 to -1.01 for anechoic targets and 1.65 to 0.45 for the hyperechoic targets.
关键词： beamforming,apodization,plane wave imaging,Ultrasound imaging
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of ultrasound reflection coefficient measurement result and its uncertainty by the method of linearization
摘要： It is shown that, if the ultrasound amplitudes before (A0) and after(A) application of the test liquid (soybean oil) to the working surface of the acoustic cell are measured using only one (working) channel of the installation, the measurement results become mutually correlated. And if A0 is measured on the reference installation channel and the amplitude A is measured on the working channel of the installation, the measurement results are not mutually correlated. And thus, it becomes possible to use the method of linearization to evaluate the measurement result and its accuracy characteristics (error and / or uncertainty).
关键词： error,uncertainty,ultrasound,acoustic cell,method of linearization,reference,liquid,measurement,working,correlation,reflection coefficient,soybean oil
更新于2025-09-23 15:21:01
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A Study of the Optical and Acoustic Spectral Characteristics by Laser Breakdown of Water in an Ultrasonic Field
摘要： A strong dependence of the optical breakdown in a liquid in the ultrasonic field on the amplitude and frequency of ultrasound is demonstrated. The increase in the intensity of spectral lines of potassium and oxygen during the optical breakdown is detected by the increase in the amplitude and frequency of ultrasound. At the same time, the effect of saturation is observed at high frequencies (above 200 kHz) and for high ultrasonic powers, when the growth in the intensity of spectral lines slows sharply down. This shows that there is no necessity to use high powers and frequencies of ultrasound to study the opto-acoustic effects during optical breakdown in a liquid.
关键词： ultrasound,spectral lines,optical breakdown,laser-spark spectroscopy,opto-acoustic effects
更新于2025-09-23 15:21:01
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<i>(Invited)</i> Fluid Spectroscopy with Piezoelectric Ultrasound MEMS Transducers
摘要： In this work, Piezoelectric Micromachined Ultrasound Transducers (PMUTs) are explored as a potential MEMS solution for fluid property monitoring. PZT based PMUTs fabricated with three different diameters—1000 μm, 500 μm, 250 μm—showing in-air resonant frequencies between 100 kHz to 2 MHz are tested in water-glycerol mixtures with glycerol concentrations varying between 0% to 80% in both static and dynamic conditions. Spectral shifts of fluid environment are PMUT vibrations with changing quantitatively related to the density and viscosity of the fluid. The density sensitivity of the PMUTs is found to increase from 27 Hz/kg.m-3 for 1000 μm to 365 Hz/kg.m-3 for 250 μm, which is in close agreement with theoretical expectations. Similarly, viscosity sensing is also explored using PMUT arrays. A through-the-fluid ultrasound transmission architecture is proposed for a potential fluid property sensor that can fill the gap of miniature sensors for sensing physical properties of various fluids.
关键词： fluid property monitoring,viscosity,density,Piezoelectric Micromachined Ultrasound Transducers,PMUTs
更新于2025-09-23 15:21:01
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Novel predictor of target vessel revascularization after coronary stent implantation: Intraluminal intensity of blood speckle on intravascular ultrasound
摘要： Background: The difference in intraluminal intensity of blood speckle (IBS) on integrated backscatter-intravascular ultrasound (IB-IVUS) across the coronary artery stenosis (i.e., ΔIBS) has been reported to negatively correlate with fractional flow reserve. Fractional flow reserve after coronary stenting is known as a predictor of target vessel revascularization (TVR). However, the relation between ΔIBS and TVR is unclear. Methods: Seven hundred and three vessels which underwent percutaneous coronary intervention with stents were screened. Vessels without IVUS-guidance and follow-up information were excluded. Intraluminal IBS values were measured using IB-IVUS in cross-sections at the ostium of the target vessel and at the distal reference of implanted stent. ΔIBS was calculated as (distal IBS) ? (ostium IBS). Results: A total of 393 vessels were included. Mean ΔIBS at postprocedure was 6.22 (cid:1) 5.65. During the follow-up period (11.2 (cid:1) 3.1 months), 24 cases (6.1%) had TVR. ΔIBS was significantly greater in the vessels with TVR than in those without (11.10 (cid:1) 5.93 vs. 5.90 (cid:1) 5.49, P <0.001). In receiver operating characteristic curve analysis, ΔIBS significantly predicted TVR (AUC 0.74, best cut-off value 8.24, P < 0.001). Multiple logistic regression analysis showed use of drug eluting stent and ΔIBS ≥ 8.24 as independent predictors of TVR. Conclusions: ΔIBS at postprocedure was significantly associated with TVR. IVUS may be able to predict TVR by physiological assessment with measurement of ΔIBS.
关键词： intravascular ultrasound,percutaneous coronary intervention,target vessel revascularization
更新于2025-09-23 15:21:01
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HIFU-induced changes in optical scattering and absorption of tissue over nine orders of thermal dose
摘要： The optical properties of tissue change during thermal ablation. Multi-modal methods such as acousto-optic (AO) and photo-acoustic (PA) imaging may provide a real-time, direct measure of lesion formation. Baseline changes in optical properties have been previously measured over limited ranges of thermal dose for tissues exposed to a temperature-controlled water bath, however, there is scant data for optical properties of lesions created by HIFU. In this work, the optical scattering and absorption coefficients from 400–1300 nm of excised chicken breast exposed to HIFU were measured using an integrating sphere spectrophotometric technique. HIFU-induced spatiotemporal temperature elevations were measured using an infrared camera and used to calculate the thermal dose delivered to a localized region of tissue. Results obtained over a range of thermal dose spanning 9 orders of magnitude show that the reduced scattering coefficient increases for HIFU exposures exceeding a thermal dose of CEM43 = 600 ± 81 cumulative equivalent minutes. HIFU-induced thermal damage results in changes in scattering over all optical wavelengths, with a 2.5-fold increase for thermal lesions exceeding 70 °C. The tissue absorption coefficient was also found to increase for thermally lesioned tissue, however, the magnitude was strongly dependent on the optical wavelength and there was substantial sample-to-sample variability, such that the existence of a threshold thermal dose could not be determined. Therapeutic windows, where the optical penetration depth is expected to be greatest, were identified in the near infrared regime centered near 900 nm and 1100 nm. These data motivate further research to improve the real-time AO and PA sensing of lesion formation during HIFU therapy as an alternative to thermometry.
关键词： thermal damage,optical properties,thermal dose,lesion,high-intensity focused ultrasound
更新于2025-09-23 15:21:01
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Pulse Wave Imaging in Carotid Artery Stenosis Human Patients in Vivo
摘要： Carotid stenosis involves narrowing of the lumen in the carotid artery potentially leading to a stroke, which is the third leading cause of death in the United States. Several recent investigations have found that plaque structure and composition may represent a more direct biomarker of plaque rupture risk compared with the degree of stenosis. In this study, pulse wave imaging was applied in 111 (n = 11, N = 13 plaques) patients diagnosed with moderate (>50%) to severe (>80%) carotid artery stenosis to investigate the feasibility of characterizing plaque properties based on the pulse wave-induced arterial wall dynamics captured by pulse wave imaging. Five (n = 5 patients, N = 20 measurements) healthy volunteers were also imaged as a control group. Both conventional and high-frame-rate plane wave radiofrequency imaging sequences were used to generate piecewise maps of the pulse wave velocity (PWV) at a single depth along stenotic carotid segments, as well as intra-plaque PWV mapping at multiple depths. Intra-plaque cumulative displacement and strain maps were also calculated for each plaque region. The Bramwell(cid:3)Hill equation was used to estimate the compliance of the plaque regions based on the PWV and diameter. Qualitatively, wave convergence, elevated PWV and decreased cumulative displacement around and/or within regions of atherosclerotic plaque were observed and may serve as biomarkers for plaque characterization. Intra-plaque mapping revealed the potential to capture wave re?ections between calci?ed inclusions and differentiate stable (i.e., calci?ed) from vulnerable (i.e., lipid) plaque components based on the intra-plaque PWV and cumulative strain. Quantitatively, one-way analysis of variance indicated that the pulse wave-induced cumulative strain was signi?cantly lower (p < 0.01) in the moderately and severely calci?ed plaques compared with the normal controls. As expected, compliance was also signi?cantly lower in the severely calci?ed plaques regions compared with the normal controls (p < 0.01). The results from this pilot study indicated the potential of pulse wave imaging coupled with strain imaging to differentiate plaques of varying stiffness, location and composition. Such ?ndings may serve as valuable information to compensate for the limitations of currently used methods for the assessment of stroke risk. (E-mail: ek2191@columbia.edu) ? 2018 World Federation for Ultrasound in Medicine & Biology. All rights reserved.
关键词： Arterial wall elasticity maps,Arterial wall motion,Atherosclerosis,Pulse wave velocity,Pulse wave imaging,High-frame-rate ultrasound,Calci?ed plaque,Arterial compliance
更新于2025-09-23 15:21:01
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Cellular Internalization-Induced Aggregation of Porous Silicon Nanoparticles for Ultrasound Imaging and Protein-Mediated Protection of Stem Cells
摘要： Nanotechnology employs multifunctional engineered materials in the nanoscale range that provides many opportunities for translational stem cell research and therapy. Here, a cell-penetrating peptide (virus-1 transactivator of transcription)–conjugated, porous silicon nanoparticle (TPSi NP) loaded with the Wnt3a protein to increase both the cell survival rate and the delivery precision of stem cell transplantation via a combinational theranostic strategy is presented. The TPSi NP with a pore size of 10.7 nm and inorganic framework enables high-efficiency loading of Wnt3a, prolongs Wnt3a release, and increases antioxidative stress activity in the labeled mesenchymal stem cells (MSCs), which are highly beneficial properties for cell protection in stem cell therapy for myocardial infarction. It is confirmed that the intracellular aggregation of TPSi NPs can highly amplify the acoustic scattering of the labeled MSCs, resulting in a 2.3-fold increase in the ultrasound (US) signal compared with that of unlabeled MSCs. The translational potential of the designed nanoagent for real-time US imaging–guided stem cell transplantation is confirmed via intramyocardial injection of labeled MSCs in a nude mouse model. It is proposed that the intracellular aggregation of protein drug–loaded TPSi NPs could be a simple but robust strategy for improving the therapeutic effect of stem cell therapy.
关键词： drug delivery,porous silicon,ultrasound imaging,cell protection,cell labeling
更新于2025-09-23 15:21:01