Publications
244 results found
Rowland EM, Riemer KA, Lichtenstein KEVIN, et al., 2022, NON-INVASIVE ASSESSMENT BY B-MODE ULTRASOUND OF ARTERIAL PULSE WAVE INTENSITY AND ITS REDUCTION DURING VENTRICULAR DYSFUNCTION, ULTRASOUND IN MEDICINE AND BIOLOGY, Vol: 49, Pages: 473-488, ISSN: 0301-5629
Riemer K, Toulemonde M, Yan J, et al., 2022, Fast and selective super-resolution ultrasound in vivo with acoustically activated nanodroplets, IEEE Transactions on Medical Imaging, Pages: 1-13, 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.
Tang M, 2022, Super-resolution ultrasound localization microscopy of microvascular structure and flow for distinguishing metastatic lymph nodes – an initial human study, Ultraschall in der Medizin, Vol: 43, Pages: 592-598, ISSN: 0172-4614
Purpose Detecting and distinguishing metastatic lymph nodes (LNs) from those with benign lymphadenopathy are crucial for cancer diagnosis and prognosis but remain a clinical challenge. A recent advance in super-resolution ultrasound (SRUS) through localizing individual microbubbles has broken the diffraction limit and tracking enabled in vivo noninvasive imaging of vascular morphology and flow dynamics at a microscopic level. In this study we hypothesize that SRUS enables quantitative markers to distinguish metastatic LNs from benign ones in patients with lymphadenopathy.Materials and Methods Clinical contrast-enhanced ultrasound image sequences of LNs from 6 patients with lymph node metastasis and 4 with benign lymphadenopathy were acquired and motion-corrected. These were then used to generate super-resolution microvascular images and super-resolved velocity maps. From these SRUS images, morphological and functional measures were obtained including micro-vessel density, fractal dimension, mean flow speed, and Local Flow Direction Irregularity (LFDI) measuring the variance in local flow direction. These measures were compared between pathologically proven reactive and metastasis LNs.Results Our initial results indicate that the difference in the indicator of flow irregularity (LFDI) derived from the SRUS images is statistically significant between the two groups. The LFDI is 60% higher in metastatic LNs compared with reactive nodes.Conclusion This pilot study demonstrates the feasibility of super-resolution ultrasound for clinical imaging of lymph nodes and the potential of using the irregularity of local blood flow directions afforded by SRUS for the characterization of LNs.
Lubel E, Sgambato BG, Barsakcioglu DY, et al., 2022, Kinematics of individual muscle units in natural contractions measured in vivo using ultrafast ultrasound, JOURNAL OF NEURAL ENGINEERING, Vol: 19, ISSN: 1741-2560
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- Citations: 2
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: 1
Yan J, Zhang T, Broughton-Venner J, et al., 2022, Super-resolution ultrasound through sparsity-based deconvolution and multi-feature tracking, IEEE Transactions on Medical Imaging, Vol: 41, Pages: 1938-1947, ISSN: 0278-0062
Ultrasound super-resolution imaging through localisation and tracking of microbubbles can achieve sub-wave-diffraction resolution in mapping both micro-vascular structure and flow dynamics in deep tissue in vivo. Currently, it is still challenging to achieve high accuracy in localisation and tracking particularly with limited imaging frame rates and in the presence of high bubble concentrations. This study introduces microbubble image features into a Kalman tracking framework, and makes the framework compatible with sparsity-based deconvolution to address these key challenges. The performance of the method is evaluated on both simulations using individual bubble signals segmented from in vivo data and experiments on a mouse brain and a human lymph node. The simulation results show that the deconvolution not only significantly improves the accuracy of isolating overlapping bubbles, but also preserves some image features of the bubbles. The combination of such features with Kalman motion model can achieve a significant improvement in tracking precision at a low frame rate over that using the distance measure, while the improvement is not significant at the highest frame rate. The in vivo results show that the proposed framework generates SR images that are significantly different from the current methods with visual improvement, and is more robust to high bubble concentrations and low frame rates.
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
Cueto C, Bates O, Strong G, et al., 2022, Stride: a flexible software platform for high-performance ultrasound computed tomography, Computer Methods and Programs in Biomedicine, Vol: 221, ISSN: 0169-2607
BACKGROUND AND OBJECTIVE: Advanced ultrasound computed tomography techniques like full-waveform inversion are mathematically complex and orders of magnitude more computationally expensive than conventional ultrasound imaging methods. This computational and algorithmic complexity, and a lack of open-source libraries in this field, represent a barrier preventing the generalised adoption of these techniques, slowing the pace of research, and hindering reproducibility. Consequently, we have developed Stride, an open-source Python library for the solution of large-scale ultrasound tomography problems. METHODS: On one hand, Stride provides high-level interfaces and tools for expressing the types of optimisation problems encountered in medical ultrasound tomography. On the other, these high-level abstractions seamlessly integrate with high-performance wave-equation solvers and with scalable parallelisation routines. The wave-equation solvers are generated automatically using Devito, a domain-specific language, and the parallelisation routines are provided through the custom actor-based library Mosaic. RESULTS: We demonstrate the modelling accuracy achieved by our wave-equation solvers through a comparison (1) with analytical solutions for a homogeneous medium, and (2) with state-of-the-art modelling software applied to a high-contrast, complex skull section. Additionally, we show through a series of examples how Stride can handle realistic numerical and experimental tomographic problems, in 2D and 3D, and how it can scale robustly from a local multi-processing environment to a multi-node high-performance cluster. CONCLUSIONS: Stride enables researchers to rapidly and intuitively develop new imaging algorithms and to explore novel physics without sacrificing performance and scalability. This will lead to faster scientific progress in this field and will significantly ease clinical translation.
Zhou X, Wang Y, Li Y, et al., 2022, Acoustic Beam Mapping for Guiding HIFU Therapy In Vivo Using Sub-Therapeutic Sound Pulse and Passive Beamforming, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 69, Pages: 1663-1673, ISSN: 0018-9294
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- Citations: 1
Bates O, Guasch L, Strong G, et al., 2022, A probabilistic approach to tomography and adjoint state methods, with an application to full waveform inversion in medical ultrasound, INVERSE PROBLEMS, Vol: 38, ISSN: 0266-5611
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- Citations: 2
Weinberg P, Riemer K, Rowland E, et al., 2022, Contrast agent free assessment of blood flow and wall shear stress in the rabbit aorta using ultrasound image velocimetry, Ultrasound in Medicine and Biology, Vol: 48, Pages: 437-449, ISSN: 0301-5629
Blood flow velocity and wall shear stress (WSS) influence and are influencedby vascular disease. Their measurement is consequently useful in the laboratory and clinic. Contrast enhanced ultrasound image velocimetry (UIV) canestimate them accurately but the need to inject contrast agents limits utility. Singular value decomposition and high frame rate imaging may rendercontrast agents dispensable. Here we determined whether contrast agent freeUIV can measure flow and WSS. In simulation, accurate measurements wereachieved with a signal-to-noise ratio of 13.5 dB or higher. Signal intensity inthe rabbit aorta increased monotonically with mechanical index and was lowest during stagnant flow and uneven across the vessel. In vivo measurementswith contrast free and contrast enhanced UIV differed by 4.4 % and 1.9 % forvelocity magnitude and angle and by 9.47 % for WSS. Bland–Altman analysis of waveforms showed good agreement between contrast free and contrast enhanced UIV. In five rabbits the root-mean-square error was as low as 0.022m/s (0.81 %) and 0.11 Pa (1.7 %). This study demonstrates that with anoptimised protocol, UIV can assess flow and WSS without contrast agents.Unlike contrast enhanced UIV, it could be routinely employed.
Cueto C, Guasch L, Cudeiro J, et al., 2022, Spatial response identification enables robust experimental ultrasound computed tomography, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 69, Pages: 27-37, ISSN: 0885-3010
Ultrasound computed tomography techniques have the potential to provide clinicians with 3-D, quantitative and high-resolution information of both soft and hard tissues such as the breast or the adult human brain. Their practical application requires accurate modeling of the acquisition setup: the spatial location, orientation, and impulse response (IR) of each ultrasound transducer. However, the existing calibration methods fail to accurately characterize these transducers unless their size can be considered negligible when compared with the dominant wavelength, which reduces signal-to-noise ratios below usable levels in the presence of high-contrast tissues such as the skull. In this article, we introduce a methodology that can simultaneously estimate the location, orientation, and IR of the ultrasound transducers in a single calibration. We do this by extending spatial response identification (SRI), an algorithm that we have recently proposed to estimate transducer IRs. Our proposed methodology replaces the transducers in the acquisition device with a surrogate model whose effective response matches the experimental data by fitting a numerical model of wave propagation. This results in a flexible and robust calibration procedure that can accurately predict the behavior of the ultrasound acquisition device without ever having to know where the real transducers are or their individual IR. Experimental results using a ring acquisition system show that SRI produces calibrations of significantly higher quality than standard methodologies across all transducers, both in transmission and in reception. Experimental full-waveform inversion (FWI) reconstructions of a tissue-mimicking phantom demonstrate that SRI generates more accurate reconstructions than those produced with standard calibration techniques.
Zaydullin R, Bharath AA, Grisan E, et al., 2022, Motion Correction Using Deep Learning Neural Networks - Effects of Data Representation, 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
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
Reavette RM, Sherwin SJ, Tang M-X, et al., 2021, Wave intensity analysis combined with machine learning can detect impaired stroke volume in simulations of heart failure, Frontiers in Bioengineering and Biotechnology, Vol: 9, Pages: 1-13, ISSN: 2296-4185
Heart failure is treatable, but in the United Kingdom, the 1-, 5- and 10-year mortality rates are 24.1, 54.5 and 75.5%, respectively. The poor prognosis reflects, in part, the lack of specific, simple and affordable diagnostic techniques; the disease is often advanced by the time a diagnosis is made. Previous studies have demonstrated that certain metrics derived from pressure-velocity-based wave intensity analysis are significantly altered in the presence of impaired heart performance when averaged over groups, but to date, no study has examined the diagnostic potential of wave intensity on an individual basis, and, additionally, the pressure waveform can only be obtained accurately using invasive methods, which has inhibited clinical adoption. Here, we investigate whether a new form of wave intensity based on noninvasive measurements of arterial diameter and velocity can detect impaired heart performance in an individual. To do so, we have generated a virtual population of two-thousand elderly subjects, modelling half as healthy controls and half with an impaired stroke volume. All metrics derived from the diameter-velocity-based wave intensity waveforms in the carotid, brachial and radial arteries showed significant crossover between groups-no one metric in any artery could reliably indicate whether a subject's stroke volume was normal or impaired. However, after applying machine learning to the metrics, we found that a support vector classifier could simultaneously achieve up to 99% recall and 95% precision. We conclude that noninvasive wave intensity analysis has significant potential to improve heart failure screening and diagnosis.
Braga M, Leow CH, Gil JH, et al., 2021, Investigating CXCR4 expression of tumor cells and the vascular compartment: A multimodal approach, PLoS One, Vol: 16, Pages: 1-21, ISSN: 1932-6203
The C-X-C chemokine receptor 4 (CXCR4) is G protein-coupled receptor that upon binding to its cognate ligand, can lead to tumor progression. Several CXCR4-targeted therapies are currently under investigation, and with it comes the need for imaging agents capable of accurate depiction of CXCR4 for therapeutic stratification and monitoring. PET agents enjoy the most success, but more cost-effective and radiation-free approaches such as ultrasound (US) imaging could represent an attractive alternative. In this work, we developed a targeted microbubble (MB) for imaging of vascular CXCR4 expression in cancer. A CXCR4-targeted MB was developed through incorporation of the T140 peptide into the MB shell. Binding properties of the T140-MB and control, non-targeted MB (NT-MB) were evaluated in MDA-MB-231 cells where CXCR4 expression was knocked-down (via shRNA) through optical imaging, and in the lymphoma tumor models U2932 and SuDHL8 (high and low CXCR4 expression, respectively) by US imaging. PET imaging of [18F]MCFB, a tumor-penetrating CXCR4-targeted small molecule, was used to provide whole-tumor CXCR4 readouts. CXCR4 expression and microvessel density were performed by immunohistochemistry analysis and western blot. T140-MB were formed with similar properties to NT-MB and accumulated sensitively and specifically in cells according to their CXCR4 expression. In NOD SCID mice, T140-MB persisted longer in tumors than NT-MB, indicative of target interaction, but showed no difference between U2932 and SuDHL8. In contrast, PET imaging with [18F]MCFB showed a marked difference in tumor uptake at 40–60 min post-injection between the two tumor models (p<0.05). Ex vivo analysis revealed that the large differences in CXCR4 expression between the two models are not reflected in the vascular compartment, where the MB are restricted; in fact, microvessel density and CXCR4 expression in the vasculature was comparable between U2932 and SuDHL8 tumors. In conclusion, we success
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
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
Teh JH, Braga M, Allott L, et al., 2021, A kit-based aluminium-[F-18]fluoride approach to radiolabelled microbubbles, Chemical Communications, Vol: 57, Pages: 11677-11680, ISSN: 1359-7345
The production of 18F-labelled microbubbles (MBs) via the aluminium-[18F]fluoride ([18F]AlF) radiolabelling method and facile inverse-electron-demand Diels–Alder (IEDDA) ‘click’ chemistry is reported. An [18F]AlF-NODA-labelled tetrazine was synthesised in excellent radiochemical yield (>95% RCY) and efficiently conjugated to a trans-cyclooctene (TCO) functionalised phospholipid (40–50% RCY), which was incorporated into MBs (40–50% RCY). To demonstrate the potential of producing 18F-labelled MBs for clinical studies, we also describe a kit-based approach which is amenable for use in a hospital radiopharmacy setting.
Morris M, Toulemonde M, Sinnett V, et al., 2021, Super-resolution ultrasound and MRI imaging for monitoring breast tumour response to radiotherapy, Publisher: ELSEVIER IRELAND LTD, Pages: S660-S661, ISSN: 0167-8140
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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Peralta L, Hajnal J, Tang M-X, et al., 2021, Effects of Aberration on Super-Resolution Ultrasound Imaging using Microbubbles, 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
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
Cueto C, Cudeiro J, Agudo OC, et al., 2021, Spatial Response Identification for Flexible and Accurate Ultrasound Transducer Calibration and its Application to Brain Imaging, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 68, Pages: 143-153, ISSN: 0885-3010
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- Citations: 5
Davies HJ, Morse SV, Copping MJ, et al., 2021, Imaging with therapeutic acoustic wavelets–short pulses enable acoustic localization when time of arrival is combined with delay and sum, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol: 68, Pages: 178-190, ISSN: 0885-3010
—Passive acoustic mapping (PAM) is an algorithm that reconstructs the location of acoustic sourcesusing an array of receivers. This technique can monitor therapeutic ultrasound procedures to confirm the spatial distribution and amount of microbubble activity induced. CurrentPAM algorithms have an excellentlateral resolution but havea poor axial resolution, making it difficult to distinguishacoustic sources within the ultrasound beams. With recentstudies demonstrating that short-length and low-pressurepulses—acoustic wavelets—have the therapeutic function,we hypothesizedthat the axial resolution could be improvedwith a quasi-pulse-echo approach and that the resolutionimprovement would depend on the wavelet’s pulse length.This article describes an algorithm that resolves acousticsources axially using time of flight and laterally using delayand-sum beamforming, which we named axial temporalposition PAM (ATP-PAM). The algorithm accommodates arapid short pulse (RaSP) sequence that can safely deliverdrugs across the blood–brain barrier. We developed ouralgorithm with simulations (k-wave) and in vitro experiments for one-, two-, and five-cycle pulses, comparingour resolution against that of two current PAM algorithms.We then tested ATP-PAM in vivo and evaluated whether thereconstructed acoustic sources mapped to drug delivery
Reavette RM, Sherwin SJ, Tang M, et al., 2020, Comparison of arterial wave intensity analysis by pressure-velocity and diameter-velocity methods in a virtual population of adult subjects., Proceedings of the Institution of Mechanical Engineers Part H: Journal of Engineering in Medicine, Vol: 234, Pages: 1260-1276, ISSN: 0954-4119
Pressure-velocity-based analysis of arterial wave intensity gives clinically relevant information about the performance of the heart and vessels, but its utility is limited because accurate pressure measurements can only be obtained invasively. Diameter-velocity-based wave intensity can be obtained noninvasively using ultrasound; however, due to the nonlinear relationship between blood pressure and arterial diameter, the two wave intensities might give disparate clinical indications. To test the magnitude of the disagreement, we have generated an age-stratified virtual population to investigate how the two dominant nonlinearities 'viscoelasticity and strain-stiffening' cause the two formulations to differ. We found strong agreement between the pressure-velocity and diameter-velocity methods, particularly for the systolic wave energy, the ratio between systolic and diastolic wave heights, and older subjects. The results are promising regarding the introduction of noninvasive wave intensities in the clinic.
Vos HJ, Voorneveld JD, Jebbink EG, et al., 2020, CONTRAST-ENHANCED HIGH-FRAME-RATE ULTRASOUND IMAGING OF FLOW PATTERNS IN CARDIAC CHAMBERS AND DEEP VESSELS, ULTRASOUND IN MEDICINE AND BIOLOGY, Vol: 46, Pages: 2875-2890, ISSN: 0301-5629
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- Citations: 8
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