Publications
262 results found
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
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
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
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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
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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- Citations: 3
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
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
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
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: 13
Choi J, Pouliopoulos A, Smith C, et al., 2020, Doppler passive acoustic mapping, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol: 67, Pages: 2692-2703, ISSN: 0885-3010
In therapeutic ultrasound using microbubbles, it is essential to drive the microbubbles into the correct type of activity and the correct location to produce the desired biological response. Although passive acoustic mapping (PAM) is capable of locating where microbubble activities are generated, it is well known that microbubbles move rapidly within the ultrasound beam. We propose a technique that can image microbubble movement by estimating their velocities within the focal volume. Microbubbles embedded within a wall-less channel of a tissue-mimicking material were sonicated using 1-MHz focused ultrasound. The acoustic emissions generated by the microbubbles were captured with a linear array (L7-4). PAM with robust Capon beamforming was used to localize the microbubble acoustic emissions. We spectrally analyzed the time trace of each position and isolated the higher harmonics. Microbubble velocity maps were constructed from the position-dependent Doppler shifts at different time points during sonication. Microbubbles moved primarily away from the transducer at velocities on the order of 1 m/s due to primary acoustic radiation forces, producing a time-dependent velocity distribution. We detected microbubble motion both away and towards the receiving array, revealing the influence of acoustic radiation forces and fluid motion due to the ultrasound exposure. High-speed optical images confirmed the acoustically-measured microbubble velocities. Doppler PAM enables passive estimation of microbubble motion and may be useful in therapeutic applications, such as drug delivery across the blood-brain barrier, sonoporation, sonothrombolysis and drug release.
Riemer K, Rowland EM, Leow CH, et al., 2020, Determining haemodynamic wall shear stress in the rabbit aorta in vivo using contrast-enhanced ultrasound image velocimetry, Annals of Biomedical Engineering, Vol: 48, Pages: 1728-1739, ISSN: 0090-6964
Abnormal blood flow and wall shear stress (WSS) can cause and be caused by cardiovascular disease. To date, however, no standard method has been established for mapping WSS in vivo. Here we demonstrate wide-field assessment of WSS in the rabbit abdominal aorta using contrast-enhanced ultrasound image velocimetry (UIV). Flow and WSS measurements were made independent of beam angle, curvature or branching. Measurements were validated in an in silico model of the rabbit thoracic aorta with moving walls and pulsatile flow. Mean errors over a cardiac cycle for velocity and WSS were 0.34 and 1.69%, respectively. In vivo time average WSS in a straight segment of the suprarenal aorta correlated highly with simulations (PC = 0.99) with a mean deviation of 0.29 Pa or 5.16%. To assess fundamental plausibility of the measurement, UIV WSS was compared to an analytic approximation derived from the Poiseuille equation; the discrepancy was 17%. Mapping of WSS was also demonstrated in regions of arterial branching. High time average WSS (TAWSSxz = 3.4 Pa) and oscillatory flow (OSIxz = 0.3) were observed near the origin of conduit arteries. In conclusion, we have demonstrated that contrast-enhanced UIV is capable of measuring spatiotemporal variation in flow velocity, arterial wall location and hence WSS in vivo with high accuracy over a large field of view.
Christensen-Jeffries K, Couture O, Dayton PA, et al., 2020, SUPER-RESOLUTION ULTRASOUND IMAGING, ULTRASOUND IN MEDICINE AND BIOLOGY, Vol: 46, Pages: 865-891, ISSN: 0301-5629
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- Citations: 184
Guasch L, Calderon Agudo O, Tang M-X, et al., 2020, Full-waveform inversion imaging of the human brain, npj Digital Medicine, Vol: 3, Pages: 1-12, ISSN: 2398-6352
Magnetic resonance imaging and X-ray computed tomography provide the two principal methods available for imaging the brain at high spatial resolution, but these methods are not easily portable and cannot be applied safely to all patients. Ultrasound imaging is portable and universally safe, but existing modalities cannot image usefully inside the adult human skull. We use in silico simulations to demonstrate that full-waveform inversion, a computational technique originally developed in geophysics, is able to generate accurate three-dimensional images of the brain with sub-millimetre resolution. This approach overcomes the familiar problems of conventional ultrasound neuroimaging by using the following: transcranial ultrasound that is not obscured by strong reflections from the skull, low frequencies that are readily transmitted with good signal-to-noise ratio, an accurate wave equation that properly accounts for the physics of wave propagation, and adaptive waveform inversion that is able to create an accurate model of the skull that then compensates properly for wavefront distortion. Laboratory ultrasound data, using ex vivo human skulls and in vivo transcranial signals, demonstrate that our computational experiments mimic the penetration and signal-to-noise ratios expected in clinical applications. This form of non-invasive neuroimaging has the potential for the rapid diagnosis of stroke and head trauma, and for the provision of routine monitoring of a wide range of neurological conditions.
Dewey M, Siebes M, Kachelrieß M, et al., 2020, Clinical quantitative cardiac imaging for the assessment of myocardial ischaemia, Nature Reviews Cardiology, Vol: 17, Pages: 427-450, ISSN: 1759-5002
Cardiac imaging has a pivotal role in the prevention, diagnosis and treatment of ischaemic heart disease. SPECT is most commonly used for clinical myocardial perfusion imaging, whereas PET is the clinical reference standard for the quantification of myocardial perfusion. MRI does not involve exposure to ionizing radiation, similar to echocardiography, which can be performed at the bedside. CT perfusion imaging is not frequently used but CT offers coronary angiography data, and invasive catheter-based methods can measure coronary flow and pressure. Technical improvements to the quantification of pathophysiological parameters of myocardial ischaemia can be achieved. Clinical consensus recommendations on the appropriateness of each technique were derived following a European quantitative cardiac imaging meeting and using a real-time Delphi process. SPECT using new detectors allows the quantification of myocardial blood flow and is now also suited to patients with a high BMI. PET is well suited to patients with multivessel disease to confirm or exclude balanced ischaemia. MRI allows the evaluation of patients with complex disease who would benefit from imaging of function and fibrosis in addition to perfusion. Echocardiography remains the preferred technique for assessing ischaemia in bedside situations, whereas CT has the greatest value for combined quantification of stenosis and characterization of atherosclerosis in relation to myocardial ischaemia. In patients with a high probability of needing invasive treatment, invasive coronary flow and pressure measurement is well suited to guide treatment decisions. In this Consensus Statement, we summarize the strengths and weaknesses as well as the future technological potential of each imaging modality.
Guasch L, Agudo OC, Tang MX, et al., 2020, Full-waveform inversion of transmitted ultrasound to image the human brain, Pages: 3517-3521, ISSN: 1052-3812
We demonstrate that acoustic full-waveform inversion (FWI), using transmitted ultrasound, is able to reconstruct accurate high-resolution images of the human brain in three dimensions in a way that would be entirely familiar to most geophysicists. Imaging the brain through the bones of the skull has close analogies to imaging sedimentary sequences beneath complex salt bodies. Here we use adaptive waveform inversion to build the skull, and use conventional FWI to recover the brain, a similar approach to that used for sub-salt imaging. This new form of non-invasive neuroimaging has the potential for rapid diagnosis of stroke and head trauma, and for the routine monitoring of a wide range of neurological conditions.
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
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
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
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, 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
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.
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