Lung mechanics are heterogeneous in virtually all respiratory diseases. Spatially mapping this heterogeneity without ionizing radiation and at bedside is not feasible with current techniques. Here, we use an Airborne Ultrasound Surface Motion Camera (AUSMC) to map the local transfer admittance of the respiratory system, in response to an oscillatory pressure source at the mouth. As a proof of concept, the local admittance maps are shown for two individuals: a COPD patient and an age-matched healthy subject. The system measures a far lower transfer admittance in the subject with COPD compared to the normal control. The consistency of this result is tested comparing interquartile ranges of the regional transfer admittance and impedance of 6 COPD patients vs 6 healthy subjects. Trial Registration Number: ClinicalTrials.gov NCT06661200. Registered on October 17th 2024.

Abstract Contactless assessment of cardiopulmonary function remains an unmet need, with current approaches relying either on subjective clinical examination or on resource-intensive imaging. We evaluated a novel multipoint airborne ultrasound surface motion camera (SMC) designed to map thoracic vibration patterns without contact and to extract clinically relevant information through data-driven analysis. In a prospective observational study, clinically characterised participants underwent short-duration acquisitions during natural breathing and externally induced oscillations. The resulting signals were transformed into spatially and frequency-resolved maps and analysed using machine learning models to discriminate healthy individuals from patients with respiratory or cardiac disease. The approach proved feasible in a clinical setting and achieved excellent discrimination between healthy individuals and respiratory patients (area under the receiver operating characteristic curve (AUC) 0.90 ± 0.07), including in patients with subtle abnormalities not detected by pulmonary function testing. Discrimination between healthy individuals and cardiac patients ranged from acceptable to excellent (AUC 0.76–0.90 depending on subgroup), with the highest performance observed in aortic stenosis. Model interpretability analyses revealed spatial and spectral patterns consistent with the known physiological organisation of lung mechanics and cardiac auscultation areas, supporting a structure–function relationship between recorded signals and underlying processes. These findings indicate that thoracic vibration transmission encodes spatially and spectrally organised information that can be captured without contact and exploited through explainable data-driven modelling. While the results require confirmation in larger populations, this approach may represent an operator-independent, low-burden extension of bedside assessment, with potential applications in early detection, triage, and monitoring of cardiopulmonary disease.

Physical examination of the thorax is key to the clinical diagnosis of respiratory diseases. Among other examination techniques, palpation evaluates the transmission of high-frequency vibrations produced by vocalizations (tactile fremitus), which helps the physicians to identify abnormalities within the respiratory system. We propose the use of an airborne ultrasound surface motion camera (AUSMC) to quantitatively map the vibrations induced by subject vocalization. This approach could make the examination of vocal fremitus quantifiable, reproducible, and archivable. Massive data collection of vocal fremitus could allow using artificial intelligence algorithms to isolate vibration patterns that could help disease identification. Until now, in contrast, the interpretation of vocal fremitus has been subject to the physician’s experience and remains subjective. In the present work, we demonstrate the capabilities of the AUSMC to measure vocal fremitus thoracic vibration maps on 77 healthy volunteers. We have observed a spatial dependence of vibration maps on vocalization frequency. We observed that the left lung generates fewer surface vibrations than the right one, which was expected according to their respective dimensions. We also discuss the implications of our findings.

The use of Autonomous Underwater Vehicles (AUVs) equipped with sonars has become increasingly important in oceanographic research, environmental monitoring, and industrial applications. Synthetic Aperture Sonars (SAS) have gained particular attention due to their ability to provide high-resolution three-dimensional (3D) images of the seafloor. However, the integration of SAS onto AUVs is still a significant technical challenge, as it requires the development of high reliability and robust systems. In this study, we present the technical details on the integration of an Interferometric Synthetic Aperture Sonar (SAMS-150) developed at Exail, on a new deep sea AUV "UlyX" developed by the French Research Institute for Exploitation of the Sea (Ifremer),as well as the results of a series of test missions conducted in real-world environments.

ObjectivesTo quantify the bias of shear wave speed (SWS) measurements between different commercial ultrasonic shear elasticity systems and a magnetic resonance elastography (MRE) system in elastic and viscoelastic phantoms.MethodsTwo elastic phantoms, representing healthy through fibrotic liver, were measured with 5 different ultrasound platforms, and 3 viscoelastic phantoms, representing healthy through fibrotic liver tissue, were measured with 12 different ultrasound platforms. Measurements were performed with different systems at different sites, at 3 focal depths, and with different appraisers. The SWS bias across the systems was quantified as a function of the system, site, focal depth, and appraiser. A single MRE research system was also used to characterize these phantoms using discrete frequencies from 60 to 500 Hz.ResultsThe SWS from different systems had mean difference 95% confidence intervals of ±0.145 m/s (±9.6%) across both elastic phantoms and ± 0.340 m/s (±15.3%) across the viscoelastic phantoms. The focal depth and appraiser were less significant sources of SWS variability than the system and site. Magnetic resonance elastography best matched the ultrasonic SWS in the viscoelastic phantoms using a 140 Hz source but had a − 0.27 ± 0.027‐m/s (−12.2% ± 1.2%) bias when using the clinically implemented 60‐Hz vibration source.ConclusionsShear wave speed reconstruction across different manufacturer systems is more consistent in elastic than viscoelastic phantoms, with a mean difference bias of < ±10% in all cases. Magnetic resonance elastographic measurements in the elastic and viscoelastic phantoms best match the ultrasound systems with a 140‐Hz excitation but have a significant negative bias operating at 60 Hz. This study establishes a foundation for meaningful comparison of SWS measurements made with different platforms.

We present a physically intuitive matrix approach for wave imaging and characterization in scattering media. The experimental proof of concept is performed with ultrasonic waves, but this approach can be applied to any field of wave physics for which multielement technology is available. The concept is that focused beam forming enables the synthesis, in transmit and receive, of an array of virtual transducers which map the entire medium to be imaged. The interelement responses of this virtual array form a focused reflection matrix from which spatial maps of various characteristics of the propagating wave can be retrieved. Here we demonstrate (i) a local focusing criterion that enables the image quality and the wave velocity to be evaluated everywhere inside the medium, including in random speckle, and (ii) a highly resolved spatial mapping of the prevalence of multiple scattering, which constitutes a new and unique contrast for ultrasonic imaging. The approach is demonstrated for a controllable phantom system and for in vivo imaging of the human abdomen. More generally, this matrix approach opens an original and powerful route for quantitative imaging in wave physics.

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Breast cancer detection in the early stages is of great importance since the prognosis, and the treatment depends more on this. Multiple techniques relying on the mechanical properties of soft tissues have been developed to help in early detection. In this study, we implemented a technique that measures the nonlinear shear modulus (NLSM) (μ NL ) in vivo and showed its utility to detect breast lesions from healthy tissue. The technique relies on the acoustoelasticity theory in quasi-incompressible media. In order to recover μNL, static elastography and supersonic shear imaging are combined to subsequently register strain maps and shear modulus maps while the medium is compressed. Then, μ NL can be recovered from the relationship between the stress, deduced from strain maps, and the shear modulus. For this study, a series of five nonlinear phantoms were built using biological tissue (pork liver) inclusions immersed in an agar-gelatin gel. Furthermore, 11 in vivo acquisitions were performed to characterize the NLSM of breast tissue. The phantom results showed a very good differentiation of the liver inclusions when measuring μ NL with a mean value of -114.1 kPa compared to -34.7 kPa for the gelatin. Meanwhile, values for the shear modulus for the liver and the gelatin were very similar, 3.7 and 3.4 kPa, respectively. In vivo NLSM mean value for the healthy breast tissue was of -95 kPa, while mean values of the benign and the malignant lesions were -619 and -806 kPa with a strong variability, respectively. This study shows the potential of the acoustoelasticity theory in quasi-incompressible medium to bring a new parameter for breast cancer diagnosis.

OBJECTIVES The aim of this study was to investigate the potential of shear wave imaging (SW), la novel ultrasound based technique, to noninvasively quantify passive diastolic myocardial stiffness in an ovine model of ischemic cardiomyopathy.BACKGROUND Evaluation of diastolic left ventricular function is critical for evaluation of heart failure and ischemia cardiomyopathy. Myocardial stiffness is known to be an important property for the evaluation of the diastolic myocardial function, but this parameter cannot be measured noninvasively by existing techniques.METHODS SWI was performed in vivo in open-chest procedures in 10 sheep. Ligation of a diagonal of the left anterior descending coronary artery was performed for 15 min (stunned group, n = 5) and 2 h (infarcted group, n = 5). Each procedure was followed by a 40-min reperfusion period. Diastolic myocardial stiffness was measured at rest, during ischemia, and after reperfusion by using noninvasive shear wave imaging. Simultaneously, end-diastolic left ventricular pressure and segmental strain were measured with a pressure catheter and sonomicrorneters during transient vena caval occlusions to obtain gold standard evaluation of myocardial stiffness using end diastolic strain stress relationship (EDSSR).RESULTS In both groups, the end-systolic circumferential strain was drastically reduced during ischemia (from 14.2 +/- 1.2% to 1.3 +/- 1.6% in the infarcted group and from 13.5 +/- 3.0% to 1.9 +/- 1.8% in the stunned group; p <0.01). SWI diastolic stiffness increased after 2 h of ischemia from 1.7 +/- 0.4 to 6.2 +/- 2.2 kPa (p < 0.05) and even more after reperfusion (12.1 +/- 4.2 kPa; p < 0.01). Diastolic myocardial stiffening was confirmed by the exponential constant coefficient of the EDSSR, which increased from 8.8 +/- 2.3 to 25.7 +/- 9.5 (p < 0.01). In contrast, SWI diastolic lstiffnesslwas unchanged in the stunned group (2.3 0.4 kPa vs 1.8 +/- 0.3 kPa, p = NS) which was confirmed also by the exponential constant of EDSSR (9.7 +/- 3.1 vs 10.2 +/- 2.3, p = NS).CONCLUSIONS Noninvasive SWI evaluation of diastolic myocardial stiffness can differentiate between stiff, noncompliant infarcted wall and softer wall containing stunned myocardium. (C) 2016 by the American College of Cardiology Foundation.

OBJECTIVES:Arterial stiffness is related to age and collagen properties of the arterial wall and can be indirectly evaluated by the pulse wave velocity (PWV). Ultrafast ultrasound imaging, a unique ultrahigh frame rate technique (>10, 000 images/s), recently emerged enabling direct measurement of carotid PWV and its variation over the cardiac cycle. Our goal was to characterize the carotid diastolic-systolic arterial stiffening using ultrafast ultrasound imaging in healthy individuals and in vascular Ehlers-Danlos syndrome (vEDS), in which collagen type III is defectuous. METHODS:Ultrafast ultrasound imaging was performed on common carotids of 102 healthy individuals and 37 consecutive patients with vEDS. Results are mean ± standard deviation. RESULTS:Carotid ultrafast ultrasound imaging PWV in healthy individuals was 5.6 ± 1.2 in early systole and 7.3 ± 2.0  m/s in end systole, and correlated with age (r = 0.48; P < 0.0001 and r = 0.68; P < 0.0001, respectively). Difference between early and end-systole PWV increased with age independently of blood pressure (r = 0.54; P < 0.0001). In patients with vEDS, ultrafast ultrasound imaging PWV was 6.0 ± 1.5 in early systole and 6.7 ± 1.5  m/s in end systole. Carotid stiffness change over the cardiac cycle was lower than in healthy people (0.021 vs. 0.057  m/s per mmHg; P = 0.0035). CONCLUSION:Ultrafast ultrasound imaging can evaluate carotid PWV and its variation over the cardiac cycle. This allowed to demonstrate the age-induced increase of the arterial diastolic-systolic stiffening in healthy people and a lower stiffening in vEDS, both characterized by arterial complications. We believe that this easy-to-use technique could offer the opportunity to go beyond the diastolic PWV to better characterize arterial stiffness change with age or other collagen alterations.

Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (<60% of Maximal Voluntary Contraction, MVC). This measurement can therefore be used to estimate changes in individual muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R2) (range: 0.86–0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R2 values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm2). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus.

Noninvasive ultrafast imaging of intrinsic waves such as electromechanical waves or remotely induced shear waves in elastography imaging techniques for human cardiac applications remains challenging. In this paper, we propose ultrafast imaging of the heart with adapted sector size by coherently compounding diverging waves emitted from a standard transthoracic cardiac phased-array probe. As in ultrafast imaging with plane wave coherent compounding, diverging waves can be summed coherently to obtain high-quality images of the entire heart at high frame rate in a full field of view. To image the propagation of shear waves with a large SNR, the field of view can be adapted by changing the angular aperture of the transmitted wave. Backscattered echoes from successive circular wave acquisitions are coherently summed at every location in the image to improve the image quality while maintaining very high frame rates. The transmitted diverging waves, angular apertures, and subaperture sizes were tested in simulation, and ultrafast coherent compounding was implemented in a commercial scanner. The improvement of the imaging quality was quantified in phantoms and in one human heart, in vivo. Imaging shear wave propagation at 2500 frames/s using 5 diverging waves provided a large increase of the SNR of the tissue velocity estimates while maintaining a high frame rate. Finally, ultrafast imaging with 1 to 5 diverging waves was used to image the human heart at a frame rate of 4500 to 900 frames/s over an entire cardiac cycle. Spatial coherent compounding provided a strong improvement of the imaging quality, even with a small number of transmitted diverging waves and a high frame rate, which allows imaging of the propagation of electromechanical and shear waves with good image quality.

Background: Vascular Ehlers-Danlos syndrome (vEDS) is a rare vascular disease resulting from autosomic dominant mutation in COL3A1 encoding for type III collagen (col.III). Impaired mechanical properties of the arterial wall caused by col.III misfolding (arterial wall thinning and increase wall stress) could expose patients to premature arterial rupture at young age. In this study, we tested whether arterial stiffness could also be impaired in those patients and therefore play a potential role in the vEDS arterial vulnerability. Arterial pulse wave velocity (PWV) is known to be very well correlated to arterial stiffness.We therefore used Sphygmocor to evaluate regional carotid-femoral PWV (cf PWV) and ultrasound Ultrafast imaging (UF) technique to evaluate the local carotid PWV. UF is a new non-invasive tool that can image tissues with high temporal resolution (up to 10,000 images/s) enabling assessment of the local carotid arterial stiffness variation during the cardiac cycle by measuring the local carotid PWV at early and end-systole. Methods: cf PWV by Sphygmocor and PWV of both carotid arteries by UF were performed on 30 patients with COL3A1 mutation and 102 healthy volunteers. 3 acquisitions of 1000 frames (1000 images/s frame rate) were performed on both common carotid arteries using a conventional linear ultrasonic probe (8MHz, 256 elements) connected to an ultrafast scanner (Aixplorer®). The arterial wall tissue velocities were computed off-line from which the two local carotid PWVs at early and end-systole were derived. cf PWV was acquired according to actual recommandations. Results are mean ± SD. Results: vEDS patients only differed from controls on age (35.5 vs. 45.0 y, p=0.03) and weight (55.8 vs. 69.8kg, p<0.0001) but not on sex ratio, systolic or diastolic blood pressures (BP), nor heart rate. The adjusted (age, sex, weight, BP) carotid PWV and cf PWV did not differ between patients and controls in early systole (6.1±1.7 vs. 5.2±1.9 m/s, p=0.07 for right carotid PWV; 5.4±1.4 vs. 4.8±1.2 m/s, p =0.94 for left carotid PWV; 7.6±1.7 vs 7.3±1.8 m/s, p=0.69 for cf PWV). However, the relative increase of carotid PWV between early and end-systole was significantly reduced in vEDS patients vs. controls (7.1% vs. 26.3% in right carotid (p=0.013) and 9.9% vs. 25.1% in left carotid (p=0.043)). Conclusion: In this study, we demonstrated a weaker systolic increase of PWV in vEDS patients which could reflect a less adaptative arterial wall stiffening during the cardiac cycle. This may explain the higher susceptibility to arterial rupture in vEDS patients

L’atteinte vasculaire périphérique est une maladie fréquente causée le plus souvent par l’athérosclérose et plus rarement par des anomalies du collagène ou d’autres composants de la paroi artérielle. Les troubles de la rigidité artérielle constituent un des phénomènes précurseurs de la maladie vasculaire périphérique et représentent dans le cas de l’athérosclérose, un marqueur de risque indépendant de survenue de maladies cardiovasculaires. Les premières techniques, développées pour l’évaluation de la rigidité artérielle, utilisent des mesures indirectes comme la vitesse de l’onde de pouls (VOP) ou l’analyse des variations de pression et de volume pour estimer la rigidité artérielle. Les techniques basées sur l’onde de pouls souffrent d’un manque de précision car elles supposent une rigidité artérielle, homogène le long du trajet de l’onde de pouls, et également constante au cours du cycle cardiaque. De plus, la mesure de la VOP peut être moins précise dans certaines situations pathologiques : syndrome métabolique, obésité, forte poitrine, mégadolico-artère. Les techniques basées sur l’analyse des variations de pression et de volume souffrent d’un manque de précision de la mesure de la pression sanguine qui ne peut se faire que de façon externe. De plus, ces techniques nécessitent un appareillage dédié, non remboursé, et compliqué à mettre en œuvre (surtout pour les techniques basées sur la variation de pression). Ces différentes raisons expliquent la faible utilisation de ces deux techniques en pratique clinique. L’imagerie ultrarapide ou « ultrafast echo » est une nouvelle modalité d’imagerie par ultrasons permettant une acquisition allant jusqu’à 10 000 images par seconde. Cette haute résolution temporelle permet de mesurer la VOP locale et la rigidité artérielle grâce à la palpation virtuelle effectuée par les ondes de cisaillement. La facilité d’application et la précision de ces deux techniques laissent présager des applications diagnostiques importantes en pathologie vasculaire. En effet, on peut réaliser en temps réel, à partir d’une sonde échographique vasculaire classique, une évaluation précise de la rigidité artérielle locale et de sa variation au cours du cycle cardiaque. Ce saut technologique permettra sans doute d’améliorer l’évaluation phénotypique des patients porteurs de maladies vasculaires, de mieux évaluer le risque cardiovasculaire des patients en prévention primaire ou secondaire, et de conduire de larges études épidémiologiques sur les risques cardiovasculaires.

An interlaboratory study of shear wave speed (SWS) estimation was performed. Commercial shear wave elastography systems from Fibroscan, Philips, Siemens and Supersonic Imagine, as well as several custom laboratory systems, were involved. Fifteen sites were included in the study. CIRS manufactured and donated 11 pairs of custom phantoms designed for the purposes of this investigation. Dynamic mechanical tests of equivalent phantom materials were also performed. The results of this study demonstrate that there is very good agreement among SWS estimation systems, but there are several sources of bias and variance that can be addressed to improve consistency of measurement results.

Peripheral vascular disease is a frequently occurring disease and is most often caused by atherosclerosis and more rarely by anomalies of the collagen or other components of the arterial wall. Arterial stiffness problems form one of the precursor phenomena of peripheral vascular disease, and in the case of atherosclerosis represents an independent risk marker for the occurrence of cardiovascular disease. The first techniques, developed to evaluate arterial stiffness, use indirect measurements such as pulse wave velocity or the analysis of variations in pressure and volume to estimate arterial wall stiffness. Techniques based on the pulse wave lack precision because they assume that arterial stiffness is uniform throughout the path of the pulse wave, and that it is constant throughout the cardiac cycle. Moreover, measuring the velocity of the pulse wave may be less precise in certain pathological situations: metabolic syndrome, obesity, large chest, mega-dolico artery. Techniques based on the analysis of variations in pressure and in volume do not accurately measure blood pressure, which can only be taken externally. In addition, these techniques require dedicated equipment, which is not reimbursed by the French health care system, and which is cumbersome to use (especially for techniques based on variation in pressure) in clinical practice. This explains why these two techniques are not used in clinical practice. Ultrafast echography is a new ultrasound imaging method that can record up to 10,000 images per second. This high temporal resolution makes it possible to measure the velocity of the local pulse wave and arterial wall stiffness thanks to the remote palpation carried out by shear wave. The ease of use and the accuracy of these two techniques suggest that these diagnostic applications will play a significant role in vascular pathology in the future. It is possible in real time, using a traditional vascular ultrasound probe, to make an accurate assessment of local arterial stiffness and of its variation during the cardiac cycle. This technological breakthrough will probably improve phenotype evaluation of patients suffering from vascular diseases, to more effectively evaluate the cardiovascular risk for patients, at primary and secondary prevention level, and to carry out broad epidemiological studies on cardiovascular risks.

Cardiac pathologies are often characterized by a significant change of myocardial stiffness, re-organization of muscle fiber structure, and the accompanying dysfunction, all of which remain challenging to be quantitatively assessed in vivo. The approach developed in this work is based on Shear Wave Imaging (SWI) a technique developed at the Langevin institute that provides real-time mapping of soft tissues viscoelastic properties. The technique relies on two successive steps: first, a shear wave is remotely induced in the myocardium using the acoustic radiation force of a focused beam, and second, the shear wave propagation is imaged using ultrafast imaging (10,000 frames per seconds). The shear modulus is derived from the shear wave speed. SWI is applied to the evaluation of myocardial stiffness on animal models of cardiomyopathy. The dynamics of change in shear modulus during the cardiac cycle is measured and the relationship between the viscoelastic properties and physiological parameters such as contractility or pathologies such as infarction is investigated. Finally, an imaging technique of the myocardial fiber orientation is developed by exploiting the anisotropy of shear wave propagation. This technique can map the complex distribution of muscle fibers in the myocardium and is compared to MR diffusion tensor imaging.

The concept of coherent compound for diverging waves is proposed to make Shear Wave Imaging at very high frame rate (up to 4000 images/sec) with a conventional cardiac phased array probe non invasively in a beating human heart. The first goal of this study was to demonstrate the improvement of the imaging performances based on spatial coherent compound with diverging wave. We show here that this technique allows tracking the shear waves with a good temporal resolution and a good signal to noise ratio which leads to a precise estimation of the local medium stiffness. The amelioration is quantified in gel and pig heart. Finally, the feasibility of this technique in vivo in a human heart is shown and shear wave velocity during diastole is estimated in the anterior wall of the left ventricle.