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Simultaneous Axial Multifocal Imaging using a Single Acoustical Transmission: a Practical Implementation
摘要： Standard ultrasound imaging techniques rely on sweeping a focused beam across a field of view; however, outside the transmission focal depth, image resolution and contrast are degraded. High-quality deep tissue in vivo imaging requires focusing the emitted field at multiple depths, yielding high resolution and high contrast ultrasound images but at the expense of a loss in frame rate. Recent developments in ultrasound technologies have led to user-programmable systems, which enable real-time dynamic control over the phase and apodization of each individual element in the imaging array. In this paper, we present a practical implementation of a method to achieve simultaneous axial multifoci using a single acoustical transmission. Our practical approach relies on the superposition of axial multifoci waveforms in a single transmission. The delay in transmission between different elements is set such that pulses constructively interfere at multiple focal depths. The proposed method achieves lateral resolution similar to successive focusing, but with an enhanced frame rate. The proposed method uses standard dynamic receive beamforming, identical to two-way focusing, and does not require additional post-processing. Thus, the method can be implemented in real-time on programmable ultrasound systems that allow different excitation signals for each element. The proposed method is described analytically and validated by laboratory experiments in phantoms and ex vivo biological samples.
关键词： beamforming,frame rate,multifoci,ultrasound imaging
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Feasibility Study of a Coherent Multi-Transducer US Imaging System
摘要： Ultrasound images can be difficult to assess, because of the limited resolution and view-dependent artefacts that are inherent to the small aperture transducers used clinically. An extended aperture has the potential to greatly improve imaging performance. This work introduces a fully coherent multi-transducer ultrasound imaging system, formed by two ultrasound transducers that are synchronized, freely located in space with a common field of view and transmit plane waves. Through coherent combination of the different transducers, a larger effective aperture is obtained and then an improved final image. First phantom images produced using this technique are presented here.
关键词： Large Aperture,Beamforming,Image Resolution,Plane Waves,Ultrasound Imaging
更新于2025-09-23 15:22:29
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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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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
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[IEEE 2019 International Conference on Advanced Computer Science and information Systems (ICACSIS) - Bali, Indonesia (2019.10.12-2019.10.13)] 2019 International Conference on Advanced Computer Science and information Systems (ICACSIS) - Wavelength Selection of Persimmon Leafusing Decision Tree Method in Visible Near-Infrared Imaging
摘要： The intima-media thickness (IMT) of the common carotid artery (CCA) is an established indicator of cardiovascular disease (CVD). There have been reports about the difference between the left and the right sides of the CCA IMT and their relation with CVD. In this paper, we propose an automated system based on image normalization, speckle reduction ?ltering, and snakes segmentation, for segmenting the CCA, perform IMT measurements, and provide the differences between the left and the right sides. The study was performed on 1104 longitudinal-section ultrasound images acquired from 568 men and 536 women out of which 125 had cardiovascular symptoms (CVD). A cardiovascular expert manually delineated the IMT for the normal and the CVD groups. The corresponding (normal versus CVD) IMT mean ± standard deviation values for the left and the right sides were 0.74 ± 0.24 versus 0.87 ± 0.24 mm and 0.70 ± 0.17 versus 0.80 ± 0.18 mm, respectively. The main ?ndings of this paper can be summarized as follows: 1) there was no signi?cant difference between the CCA left side IMT and the right side IMT. These ?ndings suggest that the measurement of the CCA IMT on one side only is needed for the normal group (and this is in agreement with other studies); 2) there were statistical signi?cant differences for the IMT measurements between the normal group and the CVD group for both the left and the right sides; 3) there was an increasing linear relationship of the left and the right IMT measurements with age for the normal group; and to a lesser extend for the CVD group; 4) no statistical signi?cant differences were found between the manual and the automated IMT measurements for both sides; and 5) the best result for classi?cation disease modeling, using support vector machines, to discriminate between the normal and the CVD groups was a 64% ± 3.5% correct classi?cations score when using both the left and the right IMT automated measurements. Further research is required for estimating differences and similarities between left and right intima media complex structure and morphology and their variability with texture features for differentiating between the normal and the CVD group.
关键词： B-mode,IMT,common carotid artery,cardiovascular disease,ultrasound imaging,intima media thickness
更新于2025-09-23 15:19:57
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[IEEE 2018 11th Biomedical Engineering International Conference (BMEiCON) - Chiang Mai, Thailand (2018.11.21-2018.11.24)] 2018 11th Biomedical Engineering International Conference (BMEiCON) - Implementation of Asymmetric Kernel Median Filtering for Real-Time Ultrasound Imaging
摘要： Ultrasound images contains speckles that could be considered as salt-and-pepper noise. Median filtering can efficiently remove the noise without blurring the edges. However, median filtering is computationally intensive and not suitable for real-time imaging. In this paper, median filtering on the intermediate ultrasound data using asymmetric median kernel sizes is proposed. To reduce the computational time, the median selection networks with compare-and-swap stages are applied instead of reducing the redundancy of the median calculation among the adjacent image pixels. Moreover, the modification of the compare-and-swap stages to suit for the GPU is also proposed. The computational times using CPU and GPU programs are compared and CNRs of the ultrasound images are also reported.
关键词： ultrasound imaging,median filtering,GPU,sorting network,median selection network
更新于2025-09-19 17:15:36
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Carbon Nitride Hollow Theranostic Nanoregulators Executing Laser-Activatable Water Splitting for Enhanced Ultrasound/Fluorescence Imaging and Cooperative Phototherapy
摘要： The limited efficacy of “smart” nanotheranostic agents in eradicating tumors calls for the development of highly desirable nanoagents with diagnostics and therapeutics. Herein, to surmount these challenges, we constructed an intelligent nanoregulator by coating mesoporous carbon nitride (C3N4) layer on core-shell nitrogen-doped graphene quantum dot (N-GQD)@hollow mesoporous silica nanosphere (HMSN), and decorated it with a P-PEG-RGD polymer, to achieve active-targeting delivery (designated as R-NCNP). Upon irradiation, the resultant R-NCNP nanoregulators exhibit significant catalytic breakdown of water molecules causing sustainable elevation of oxygen level owing to the C3N4 shell, which facilitates tumor oxygenation and relieves tumor hypoxia. The generated oxygen bubbles serve as an echogenic source triggering tissue impedance mismatch thereby enhancing the generation of echogenicity signal, making them laser-activatable ultrasound imaging agents. In addition, the encapsulated photosensitizers and C3N4 layered photosensitizer are simultaneously activated to maximize the yield of ROS, actualizing a triple-photosensitizer hybrid nanosystem exploited for enhanced PDT. Intriguingly, the N-GQDs endow R-NCNP nanoregulator with photothermal effect for hyperthemia, making it exhibit considerable photothermal outcomes and infrared thermal imaging (IRT). Importantly, further analysis reveals that the polymer-modified R-NCNPs actively target specific tumor tissues, and display a triple-modal US/IRT/FL imaging-assisted cooperative PTT/PDT for real-time monitoring of tumor ablation and therapeutic evaluation. The rational synergy of triple-model PDT and efficient PTT in designed nanoregulator confers excellent anticancer effects, as evidenced by in vitro and in vivo assays, which might explore more possibilities in personalized cancer treatment.
关键词： O2-elevation,ultrasound imaging,water splitting,cancer treatment,nanoregulator
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Ultrasonics Symposium (IUS) - Glasgow, United Kingdom (2019.10.6-2019.10.9)] 2019 IEEE International Ultrasonics Symposium (IUS) - Non-Contact laser ultrasound (N-CLUS) system for medical imaging and elastography
摘要： MIT Lincoln Laboratory, the Medical Device Realization Center (MEDRC) at MIT, and the Massachusetts General Hospital (MGH) are collaboratively developing a novel optical system that acquires ultrasound images within the human body without physical contact to the patient. The system is termed, non-contact laser ultrasound (N-CLUS) and yields anatomical images in tissue and bone and can also measure elastographic properties, in-vivo, all from an operational standoff of a few inches to several meters as desired. N-CLUS employs a pulsed laser that converts optical energy into ultrasonic waves at the skin surface via photoacoustic mechanisms, while, a laser Doppler vibrometer measures reflected-emerging ultrasonic waves from tissue at depth at the skin surface. The key of the N-CLUS approach is driven by shallow optical absorptivity that creates an acoustic source that enables ultrasound propagation deeper into the tissue. We discuss the motivation of the non-contact laser concept, its development path involving signal generation, skin and eye safe laser measurement, and system design perspectives. Elastogrphic measurements are then demonstrated with determination of bone elastic moduli for beef rib within tissue. N-CLUS images from soft tissue specimens are also compared with commercial ultrasound, showing that the noncontact optical approach may have potential as a viable method in medical ultrasound.
关键词： laser Doppler vibrometry,photoacoustics,non-contact laser ultrasound,medical ultrasound imaging,elastography
更新于2025-09-16 10:30:52
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Toroidally focused sensor array for real-time laser-ultrasonic imaging: the first experimental study
摘要： In this paper we report on the first toroidally focused 2D real-time laser-ultrasonic imaging system and a modified filtered back projection algorithm that can be used in the region near the waist of the astigmatic laser-ultrasonic probe beam. The system is capable of visualizing an acupuncture needle 0.2 mm in diameter located at ~4 cm depth in water. The lateral spatial resolution is better than ~0.32 mm and axial spatial resolution is ~30 μm. The achieved frame rate is up to 30 Hz. The depth dependency of the sensitivity region width and lateral resolution are experimentally measured and discussed. The array is intended to be used as a part of combined real-time photoacoustic and laser-ultrasonic imaging system.
关键词： laser ultrasound imaging,back projection,tomography,real-time,focused array,laser ultrasound,toroidal array
更新于2025-09-16 10:30:52