Publications
54 results found
Wang B, Riemer K, Toulemonde M, et al., 2024, Broad Elevation Projection Super-Resolution Ultrasound (BEP-SRUS) imaging with a 1D unfocused linear array, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 71, Pages: 255-265, ISSN: 0885-3010
Super-resolution ultrasound (SRUS) through localizing spatially isolated microbubbles (MBs) has been demonstrated to overcome the wave diffraction limit and reveal the microvascular structure and flow information at the microscopic scale. However, 3-D SRUS imaging remains a challenge due to the fabrication and computational complexity of 2-D matrix array probes. Inspired by X-ray radiography which can present information within a volume in a single projection image with much simpler hardware than X-ray computerized tomography (CT), this study investigates the feasibility of broad elevation projection super-resolution (BEP-SR) ultrasound using a 1-D unfocused linear array. Both simulation and in vitro experiments were conducted on 3-D microvessel phantoms. In vivo demonstration was done on the Rabbit kidney. Data from a 1-D linear array with and without an elevational focus were synthesized by summing up row signals acquired from a 2-D matrix array with and without delays. A full 3-D reconstruction was also generated as the reference, using the same data of the 2-D matrix array but without summing row signals. Results show that using an unfocused 1-D array probe, BEP-SR can capture significantly more information within a volume in both vascular structure and flow velocity than the conventional 1-D elevational-focused probe. Compared with the 2-D projection image of the full 3-D SRUS results using the 2-D array probe with the same aperture size, the 2-D projection SRUS image of BEP-SR has similar volume coverage, using 32 folds fewer independent elements. This study demonstrates BEP-SR’s ability of high-resolution imaging of microvascular structures and flow velocity within a 3-D volume at significantly reduced costs. The proposed BEP method could significantly benefit the clinical translation of the SRUS imaging technique by making it more affordable and repeatable.
Yan J, Wang B, Riemer K, et al., 2023, Fast 3D super-resolution ultrasound with adaptive weight-based beamforming, IEEE Transactions on Biomedical Engineering, Vol: 70, Pages: 2752-2761, ISSN: 0018-9294
Objective: Super-resolution ultrasound (SRUS) imaging through localising and tracking sparse microbubbles has been shown to reveal microvascular structure and flow beyond the wave diffraction limit. Most SRUS studies use standard delay and sum (DAS) beamforming, where high side lobes and broad main lobes make isolation and localisation of densely distributed bubbles challenging, particularly in 3D due to the typically small aperture of matrix array probes. Method: This study aimed to improve 3D SRUS by implementing a new fast 3D coherence beamformer based on channel signal variance. Two additional fast coherence beamformers, that have been implemented in 2D were implemented in 3D for the first time as comparison: a nonlinear beamformer with p-th root compression and a coherence factor beamformer. The 3D coherence beamformers, together with DAS, were compared in computer simulation, on a microflow phantom and in vivo. Results: Simulation results demonstrated that all three adaptive weight-based beamformers can narrow the main lobe suppress the side lobes, while maintaining the weaker scatter signals. Improved 3D SRUS images of microflow phantom and a rabbit kidney within a 3-second acquisition were obtained using the adaptive weight-based beamformers, when compared with DAS. Conclusion: The adaptive weight-based 3D beamformers can improve the SRUS and the proposed variance-based beamformer performs best in simulations and experiments. Significance: Fast 3D SRUS would significantly enhance the potential utility of this emerging imaging modality in a broad range of biomedical applications.
Nie L, Toulemonde M, Tang MX, et al., 2023, A human ear-inspired ultrasonic transducer (HEUT) for 3D localization of sub-wavelength scatterers, Applied Physics Letters, Vol: 123, ISSN: 0003-6951
The proposed technology aims to enable 3D localization of scatterers using single element ultrasonic transducers, which are traditionally limited to 1D measurements. This is achieved by designing a bespoke acoustic lens with a spiral-shaped pattern similar to the human outer ear, a shape that has evolved for sound source localization. This lens breaks the surface symmetry of the transducer, allowing ultrasonic waves arriving from different directions to be encoded in a certain way that can later be decoded to extract directional information. By employing the mechanism of spatial-encoding of the received signals and decoding via signal processing, the location of sub-wavelength scatterers can be detected in 3D with a single measurement for sparsely distributed scatterers. The proposed technology is first verified through a simulation study, and then 3D printed acoustic lenses are used to demonstrate the 3D encoding functionality of the Human Ear-inspired Ultrasonic Transducer (HEUT) experimentally. A framework is created to localize scatterers in 3D by processing received signals acquired by a HEUT prototype. With this technology, a single transducer can obtain multi-dimensional information with a single pulse-echo measurement, reducing the number of elements required for performing 3D ultrasound localization. The proposed spatial-encoding and -decoding technology can be applied to other wave-based imaging methods to develop affordable, practical, and compact sensing devices.
Seligman H, Patel SB, Alloula A, et al., 2023, Development of artificial intelligence tools for invasive Doppler-based coronary microvascular assessment., Eur Heart J Digit Health, Vol: 4, Pages: 291-301
AIMS: Coronary flow reserve (CFR) assessment has proven clinical utility, but Doppler-based methods are sensitive to noise and operator bias, limiting their clinical applicability. The objective of the study is to expand the adoption of invasive Doppler CFR, through the development of artificial intelligence (AI) algorithms to automatically quantify coronary Doppler quality and track flow velocity. METHODS AND RESULTS: A neural network was trained on images extracted from coronary Doppler flow recordings to score signal quality and derive values for coronary flow velocity and CFR. The outputs were independently validated against expert consensus. Artificial intelligence successfully quantified Doppler signal quality, with high agreement with expert consensus (Spearman's rho: 0.94), and within individual experts. Artificial intelligence automatically tracked flow velocity with superior numerical agreement against experts, when compared with the current console algorithm [AI flow vs. expert flow bias -1.68 cm/s, 95% confidence interval (CI) -2.13 to -1.23 cm/s, P < 0.001 with limits of agreement (LOA) -4.03 to 0.68 cm/s; console flow vs. expert flow bias -2.63 cm/s, 95% CI -3.74 to -1.52, P < 0.001, 95% LOA -8.45 to -3.19 cm/s]. Artificial intelligence yielded more precise CFR values [median absolute difference (MAD) against expert CFR: 4.0% for AI and 7.4% for console]. Artificial intelligence tracked lower-quality Doppler signals with lower variability (MAD against expert CFR 8.3% for AI and 16.7% for console). CONCLUSION: An AI-based system, trained by experts and independently validated, could assign a quality score to Doppler traces and derive coronary flow velocity and CFR. By making Doppler CFR more automated, precise, and operator-independent, AI could expand the clinical applicability of coronary microvascular assessment.
Riemer K, Toulemonde M, Yan J, et al., 2023, Fast and selective super-resolution ultrasound in vivo with acoustically activated nanodroplets, IEEE Transactions on Medical Imaging, Vol: 42, Pages: 1056-1067, ISSN: 0278-0062
Perfusion by the microcirculation is key to the development, maintenance and pathology of tissue. Its measurement with high spatiotemporal resolution is consequently valuable but remains a challenge in deep tissue. Ultrasound Localization Microscopy (ULM) provides very high spatiotemporal resolution but the use of microbubbles requires low contrast agent concentrations, a long acquisition time, and gives little control over the spatial and temporal distribution of the microbubbles. The present study is the first to demonstrate Acoustic Wave Sparsely-Activated Localization Microscopy (AWSALM) and fast-AWSALM for in vivo super-resolution ultrasound imaging, offering contrast on demand and vascular selectivity. Three different formulations of acoustically activatable contrast agents were used. We demonstrate their use with ultrasound mechanical indices well within recommended safety limits to enable fast on-demand sparse activation and destruction at very high agent concentrations. We produce super-localization maps of the rabbit renal vasculature with acquisition times between 5.5 s and 0.25 s, and a 4-fold improvement in spatial resolution. We present the unique selectivity of AWSALM in visualizing specific vascular branches and downstream microvasculature, and we show super-localized kidney structures in systole (0.25 s) and diastole (0.25 s) with fast-AWSALM outdoing microbubble based ULM. In conclusion, we demonstrate the feasibility of fast and selective measurement of microvascular dynamics in vivo with subwavelength resolution using ultrasound and acoustically activatable nanodroplet contrast agents.
Cudeiro-blanco J, Cueto C, Bates O, et al., 2022, DESIGN AND CONSTRUCTION OF A LOW-FREQUENCY ULTRASOUND ACQUISITION DEVICE FOR 2-D BRAIN IMAGING USING FULL-WAVEFORM INVERSION, ULTRASOUND IN MEDICINE AND BIOLOGY, Vol: 48, Pages: 1995-2008, ISSN: 0301-5629
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- Citations: 6
Hirata S, Hagihara Y, Yoshida K, et al., 2022, Evaluation of contrast enhancement ultrasound images of Sonazoid microbubbles in tissue-mimicking phantom obtained by optimal Golay pulse compression, JAPANESE JOURNAL OF APPLIED PHYSICS, Vol: 61, ISSN: 0021-4922
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- Citations: 3
Nie L, Toulemonde M, Tang M-X, et al., 2022, 3D Localization of Scatterers with a Spiral-Shaped Acoustic Lens, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, ISSN: 1948-5719
Sze S, Bates O, Toulemonde M, et al., 2022, Semi-automatic Segmentation of the Myocardium in High-Frame Rate and Clinical Contrast Echocardiography Images, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, ISSN: 1948-5719
Wang B, Yan J, Riemer K, et al., 2022, Comparison of localization methods for 3D Super-Resolution Ultrasound Imaging, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, ISSN: 1948-5719
Zhou X, Toulemonde M, Zhou X, et al., 2021, Volumetric Flow Estimation in a Coronary Artery Phantom Using High-Frame-Rate Contrast-Enhanced Ultrasound, Speckle Decorrelation, and Doppler Flow Direction Detection, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 68, Pages: 3299-3308, ISSN: 0885-3010
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- Citations: 1
Hansen-Shearer J, Lerendegui M, Toulemonde M, et al., 2021, Ultrafast 3D ultrasound imaging using row-column array specific Frame-Multiply-and-Sum beamforming, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 69, Pages: 480-488, ISSN: 0885-3010
Row-column arrays have been shown to be able to generate 3-D ultrafast ultrasound images with an order of magnitude less independent electronic channels than traditional 2-D matrix arrays. Unfortunately, row-column array images suffer from major imaging artefacts due to high side-lobes, particularly when operating at high frame rates. This paper proposes a rowcolumn specific beamforming technique, for orthogonal plane wave transmissions, that exploits the incoherent nature of certain row-column array artefacts. A series of volumetric images are produced using row or column transmissions of 3-D plane waves. The voxel-wise geometric mean of the beamformed volumetric images from each row and column pair is taken prior to compounding, which drastically reduces the incoherent imaging artefacts in the resulting image compared to traditional coherent compounding. The effectiveness of this technique was demonstrated in silico and in vitro, and the results show a significant reduction in side-lobe level with over 16 dB improvement in sidelobe to main-lobe energy ratio. Significantly improved contrast was demonstrated with contrast ratio increased by ∼10dB and generalised contrast-to-noise ratio increased by 158% when using the proposed new method compared to existing delay and sum during in vitro studies. The new technique allowed for higher quality 3-D imaging whilst maintaining high frame rate potential
Hirata S, Leow CH, Toulemonde MEG, et al., 2021, Selection on Golay complementary sequences in binary pulse compression for microbubble detection, JAPANESE JOURNAL OF APPLIED PHYSICS, Vol: 60, ISSN: 0021-4922
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- Citations: 3
Riemer K, Toulemonde M, Lerendegui M, et al., 2021, Towards real-time super-resolution imaging with fastAWSALM, The Journal of the Acoustical Society of America, Vol: 149, Pages: A64-A64, ISSN: 0001-4966
<jats:p>Localization-based ultrasound super-resolution imaging can visualize the microvascular structure beyond the diffraction limit but is sensitive to contrast concentration and requires acquisition for seconds. Low-boiling-point phase-change nanodroplets achieve super-resolved images with subsecond temporal resolution through activation and destruction with high frame rate plane waves in real-time.</jats:p>
Wang B, Riemer K, Toulemonde M, et al., 2021, Volumetric Super-Resolution Ultrasound with a 1D array probe: a simulation study, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Dumas R, Riemer K, Toulemonde M, et al., 2021, 4D ultrafast blood flow imaging comparison: vector Doppler, transverse oscillation and speckle tracking, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Harput S, Toulemonde M, Ramalli A, et al., 2020, Quantitative Microvessel Analysis with 3-D Super-Resolution Ultrasound and Velocity Mapping, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
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- Citations: 5
Zhang G, Toulemonde M, Riemer K, et al., 2020, Effects of Mechanical Index on Repeated Sparse Activation of Nanodroplets In Vivo, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Toulemonde M, Harput S, Tiennot T, et al., 2020, 3D super localized flow with locally and acoustically activated nanodroplets and high frame rate imaging using a matrix array, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Nie L, Moo JTM, Toulemonde M, et al., 2020, Localization of a Scatterer in 3D with a Single Measurement and Single Element Transducer, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Berthaume MA, Toulemonde M, Peralta L, et al., 2020, Detecting and Characterizing the Fabella with High Frame-Rate Ultrasound Imaging, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Riemer K, Toulemonde M, Rowland EM, et al., 2020, 4D Blood Flow and Wall Shear Stress measured using Volumetric Ultrasound Image Velocimetry, IEEE International Ultrasonics Symposium (IEEE IUS), Publisher: IEEE, ISSN: 1948-5719
Zhang G, Harput S, Toulemonde M, et al., 2019, Acoustic wave sparsely-activated localization microscopy (AWSALM): in vivo fast ultrasound super-resolution imaging using nanodroplets, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, Pages: 1930-1933, ISSN: 1948-5719
Current localization-based super-resolution ultrasound imaging requires a low concentration of flowing microbubbles to visualize microvasculature beyond the diffraction limit and acquisition is slow. Nanodroplets offer a promising solution as they can be sparsely activated and deactivated on-demand. In this study, acoustic wave sparsely-activated localization microscopy (AWSALM) using activation and deactivation of nanodroplets, an acoustic counterpart of photo-activated localization microscopy (PALM) which is less dependent on agent concentration and the presence of flow, is demonstrated for super-resolution imaging in deep tissues in vivo. An in vivo super-resolution image of a rabbit kidney is obtained in 1.1 seconds using AWSALM, where micro-vessels with apparent sizes far below the half-wavelength of 220 μm were visualized. This preliminary result demonstrates the feasibility of applying AWSALM for in vivo super-resolution imaging.
Toulemonde M, Zhang G, Eckersley RJ, et al., 2019, Flow Visualization Through Locally Activated Nanodroplets and High Frame Rate Imaging, IEEE International Ultrasonics Symposium, IUS. 2018, ISSN: 1948-5719
© 2018 IEEE. Blood flow visualization and quantification with ultrasound contrast agents using High-Frame-Rate (HFR) imaging has been investigated but the real-time feedback is limited because of the high computational cost. Nanodroplets have been investigated as an alternative to microbubble contrast agents, due to their smaller size, longer in vivo half-life, and spatial and temporal control on activation. In this work, a non-invasive flow visualization method is proposed through non-invasively "injecting" contrast agents by using locally activatinged decafluorobutane nanodroplets and HFR diverging imaging. Vortexes, residual flows or global flow patterns can be visualized thanks to the high temporal resolution and low computational complexity image processing.
Harput S, Christensen-Jeffries K, Ramalli A, et al., 2019, 3-D super-resolution ultrasound (SR-US) imaging with a 2-D sparse array
High frame rate 3-D ultrasound imaging technology combined withsuper-resolution processing method can visualize 3-D microvascular structuresby overcoming the diffraction limited resolution in every spatial direction.However, 3-D super-resolution ultrasound imaging using a full 2-D arrayrequires a system with large number of independent channels, the design ofwhich might be impractical due to the high cost, complexity, and volume of dataproduced. In this study, a 2-D sparse array was designed and fabricated with 512elements chosen from a density-tapered 2-D spiral layout. High frame ratevolumetric imaging was performed using two synchronized ULA-OP 256 researchscanners. Volumetric images were constructed by coherently compounding 9-angleplane waves acquired in 3 milliseconds at a pulse repetition frequency of 3000Hz. To allow microbubbles sufficient time to move between consequent compoundedvolumetric frames, a 7-millisecond delay was introduced after each volumeacquisition. This reduced the effective volume acquisition speed to 100 Hz andthe total acquired data size by 3.3-fold. Localization-based 3-Dsuper-resolution images of two touching sub-wavelength tubes were generatedfrom 6000 volumes acquired in 60 seconds. In conclusion, this work demonstratesthe feasibility of 3D super-resolution imaging and super-resolved velocitymapping using a customized 2D sparse array transducer.
Stanziola A, Toulemonde M, Li Y, et al., 2019, Motion artifacts and correction in multipulse high-frame rate contrast-enhanced ultrasound, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 66, Pages: 417-420, ISSN: 0885-3010
High-frame-rate (HFR) ultrasound (US) imaging and contrast-enhanced US (CEUS) are often implemented using multipulse transmissions, to enhance image quality. Multipulse approaches, however, suffer from degradation in the presence of motion, especially when coherent compounding and CEUS are combined. In this paper, we investigate this effect on the intensity of HFR CEUS in deep tissue imaging using simulations and in vivo contrast echocardiography (CE). The simulation results show that the motion artifact is much higher when the flow is in an axial direction than a lateral direction. Using a pulse repetition frequency suitable for cardiac imaging, a motion of 35 cm/s can cause as much as 28.5 dB decrease in image intensity, where compounding can contribute up to 18.7 dB of intensity decrease (11 angles). These motion effects are also demonstrated for in vivo cardiac HFR CE, where the large velocities of both the myocardium and the blood are present. Intensity reductions of 10.4 dB are readily visible in the chamber. Finally, we demonstrate how performing motion–correction before pulse inversion compounding greatly reduces such motion artifact and improve image signal-to-noise ratio and contrast.
Harput S, Fong LH, Stanziola A, et al., 2019, Super-Resolution Ultrasound Image Filtering with Machine-Learning to Reduce the Localization Error, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, Pages: 2118-2121, ISSN: 1948-5719
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- Citations: 2
Harput S, Zhang G, Toulemonde M, et al., 2019, Activation and 3D Imaging of Phase-change Nanodroplet Contrast Agents with a 2D Ultrasound Probe, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, Pages: 2275-2278, ISSN: 1948-5719
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- Citations: 2
Stanziola A, Toulemonde M, Papadopoulou V, et al., 2019, Sparse Image Reconstruction for Contrast Enhanced Cardiac Ultrasound using Diverging Waves, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE, Pages: 908-911, ISSN: 1948-5719
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- Citations: 1
Harput S, Christensen-Jeffries K, Brown J, et al., 2018, 3-D super-resolution ultrasound (SR-US) imaging using a 2-D sparse array with high volumetric imaging rate, IEEE International Ultrasonics Symposium (IUS), Publisher: IEEE
Super-resolution ultrasound imaging has been sofar achieved in 3-D by mechanically scanning a volume witha linear probe, by co-aligning multiple linear probes, by usingmultiplexed 3-D clinical ultrasound systems, or by using 3-D ultrasound research systems. In this study, a 2-D sparsearray was designed with 512 elements according to a density-tapered 2-D spiral layout and optimized to reduce the sidelobesof the transmitted beam profile. High frame rate volumetricimaging with compounded plane waves was performed usingtwo synchronized ULA-OP256 systems. Localization-based 3-Dsuper-resolution images of two touching sub-wavelength tubeswere generated from a 120 second acquisition.
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