@article{minh_muller_raum_2022, title={Estimation of Thickness and Speed of Sound for Transverse Cortical Bone Imaging Using Phase Aberration Correction Methods: An In Silico and Ex Vivo Validation Study}, volume={12}, ISSN={["2076-3417"]}, DOI={10.3390/app12105283}, abstractNote={Delay-and-sum (DAS) beamforming of backscattered echoes is used for conventional ultrasound imaging. Although DAS beamforming is well suited for imaging in soft tissues, refraction, scattering, and absorption, porous mineralized tissues cause phase aberrations of reflected echoes and subsequent image degradation. The recently developed refraction corrected multi-focus technique uses subsequent focusing of waves at variable depths, the tracking of travel times of waves reflected from outer and inner cortical bone interfaces, the estimation of the shift needed to focus from one interface to another to determine cortical thickness (Ct.Th), and the speed of sound propagating in a radial bone direction (Ct.ν11). The method was validated previously in silico and ex vivo on plate shaped samples. The aim of this study was to correct phase aberration caused by bone geometry (i.e., curvature and tilt with respect to the transducer array) and intracortical pores for the multi-focus approach. The phase aberration correction methods are based on time delay estimation via bone geometry differences to flat bone plates and via the autocorrelation and cross correlation of the reflected ultrasound waves from the endosteal bone interface. We evaluate the multi-focus approach by incorporating the phase aberration correction methods by numerical simulation and one experiment on a human tibia bone, and analyze the precision and accuracy of measuring Ct.Th and Ct.ν11. Site-matched reference values of the cortical thickness of the human tibia bone were obtained from high-resolution peripheral computed tomography. The phase aberration correction methods resulted in a more precise (coefficient of variation of 5.7%) and accurate (root mean square error of 6.3%) estimation of Ct.Th, and a more precise (9.8%) and accurate (3.4%) Ct.ν11 estimation, than without any phase aberration correction. The developed multi-focus method including phase aberration corrections provides local estimations of both cortical thickness and sound velocity and is proposed as a biomarker of cortical bone quality with high clinical potential for the prevention of osteoporotic fractures.}, number={10}, journal={APPLIED SCIENCES-BASEL}, author={Minh, Huong Nguyen and Muller, Marie and Raum, Kay}, year={2022}, month={May} }
 @article{demi_wolfram_klersy_de silvestri_ferretti_muller_miller_feletti_welnicki_buda_et al._2022, title={New International Guidelines and Consensus on the Use of Lung Ultrasound}, ISSN={["1550-9613"]}, DOI={10.1002/jum.16088}, abstractNote={Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.}, journal={JOURNAL OF ULTRASOUND IN MEDICINE}, author={Demi, Libertario and Wolfram, Frank and Klersy, Catherine and De Silvestri, Annalisa and Ferretti, Virginia Valeria and Muller, Marie and Miller, Douglas and Feletti, Francesco and Welnicki, Marcin and Buda, Natalia and et al.}, year={2022}, month={Aug} }
 @article{chen_peng_wu_huang_kim_traylor_muller_chhatbar_nam_feng_et al._2022, title={Numerical and experimental evaluation of low-intensity transcranial focused ultrasound wave propagation using human skulls for brain neuromodulation}, volume={11}, ISSN={["2473-4209"]}, DOI={10.1002/mp.16090}, abstractNote={Low-intensity transcranial focused ultrasound (tFUS) has gained considerable attention as a promising noninvasive neuromodulatory technique for human brains. However, the complex morphology of the skull hinders scholars from precisely predicting the acoustic energy transmitted and the region of the brain impacted during the sonication. This is due to the fact that different ultrasound frequencies and skull morphology variations greatly affect wave propagation through the skull.Although the acoustic properties of human skull have been studied for tFUS applications, such as tumor ablation using a multielement phased array, there is no consensus about how to choose a single-element focused ultrasound (FUS) transducer with a suitable frequency for neuromodulation. There are interests in exploring the magnitude and dimension of tFUS beam through human parietal bone for modulating specific brain lobes. Herein, we aim to investigate the wave propagation of tFUS on human skulls to understand and address the concerns above.Both experimental measurements and numerical modeling were conducted to investigate the transmission efficiency and beam pattern of tFUS on five human skulls (C3 and C4 regions) using single-element FUS transducers with six different frequencies (150-1500 kHz). The degassed skull was placed in a water tank, and a calibrated hydrophone was utilized to measure acoustic pressure past it. The cranial computed tomography scan data of each skull were obtained to derive a high-resolution acoustic model (grid point spacing: 0.25 mm) in simulations. Meanwhile, we modified the power-law exponent of acoustic attenuation coefficient to validate numerical modeling and enabled it to be served as a prediction tool, based on the experimental measurements.The transmission efficiency and -6 dB beamwidth were evaluated and compared for various frequencies. An exponential decrease in transmission efficiency and a logarithmic decrease of -6 dB beamwidth with an increase in ultrasound frequency were observed. It is found that a >750 kHz ultrasound leads to a relatively lower tFUS transmission efficiency (<5%), whereas a <350 kHz ultrasound contributes to a relatively broader beamwidth (>5 mm). Based on these observations, we further analyzed the dependence of tFUS wave propagation on FUS transducer aperture size.We successfully studied tFUS wave propagation through human skulls at different frequencies experimentally and numerically. The findings have important implications to predict tFUS wave propagation for ultrasound neuromodulation in clinical applications, and guide researchers to develop advanced ultrasound transducers as neural interfaces.}, journal={MEDICAL PHYSICS}, author={Chen, Mengyue and Peng, Chang and Wu, Huaiyu and Huang, Chih-Chung and Kim, Taewon and Traylor, Zachary and Muller, Marie and Chhatbar, Pratik Y. and Nam, Chang S. and Feng, Wuwei and et al.}, year={2022}, month={Nov} }
 @article{white_alexanderian_yousefian_karbalaeisadegh_bekele-maxwell_kasali_banks_talmant_grimal_muller_2022, title={Using ultrasonic attenuation in cortical bone to infer distributions on pore size}, volume={109}, ISSN={["1872-8480"]}, DOI={10.1016/j.apm.2022.05.024}, abstractNote={• Pore size distribution in cortical bone is inferred using ultrasound interrogation. • Variational regularization stabilizes nonparametric inverse problems. • Ultrasound attenuation is modeled as dependent upon a distributed parameter. In this work we infer the underlying distribution on pore radius in human cortical bone samples using ultrasonic attenuation data. We first discuss how to formulate polydisperse attenuation models using a probabilistic approach and the Waterman Truell model for scattering attenuation. We then compare the Independent Scattering Approximation and the higher-order Waterman Truell models’ forward predictions for total attenuation in polydisperse samples. Following this, we formulate an inverse problem under the Prohorov Metric Framework coupled with variational regularization to stabilize this inverse problem. We then use experimental attenuation data taken from human cadaver samples and solve inverse problems resulting in nonparametric estimates of the probability density function on pore radius. We compare these estimates to the “true” microstructure of the bone samples determined via microCT imaging. We find that our methodology allows us to reliably estimate the underlying microstructure of the bone from attenuation data.}, journal={APPLIED MATHEMATICAL MODELLING}, author={White, R. D. and Alexanderian, A. and Yousefian, O. and Karbalaeisadegh, Y. and Bekele-Maxwell, K. and Kasali, A. and Banks, H. T. and Talmant, M. and Grimal, Q. and Muller, M.}, year={2022}, month={Sep}, pages={819–832} }
 @article{chen_peng_kim_chhatbar_muller_feng_jiang_2021, title={Biosafety of Low-Intensity Pulsed Transcranial Focused Ultrasound Brain Stimulation - A Human Skull Study}, volume={11593}, ISSN={["1996-756X"]}, DOI={10.1117/12.2582487}, abstractNote={Among a variety of existing modalities for noninvasive brain stimulation (NIBS), low-intensity pulsed transcranial focused ultrasound (tFUS) is a promising technique to precisely stimulate deep brain structures due to its high spatial specificity and superior penetration depth. While tFUS is gaining momentum as an emerging NIBS technique, an advisable biosafety-associated combination of sonication parameters including duty cycle and power input remains to be explored. In this study, biosafety of low-intensity pulsed tFUS using various sonication parameters was evaluated by measuring acoustic intensities and temperature variations across a piece of real human skull. The results showed that ISPTA above 480 mW/cm^2 is likely to induce an excessive temperature rise for a sonication duration of 160 seconds. Also, the skull base effect and ultrasound transducer self-heating effect should be noted during the sonication. Based on the findings in this study, an initial biosafety guide was discussed for the future investigation of ultrasound-mediated NIBS.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS XV}, author={Chen, Mengyue and Peng, Chang and Kim, Taewon and Chhatbar, Pratik Y. and Muller, Marie and Feng, Wuwei and Jiang, Xiaoning}, year={2021} }
 @article{roshankhah_blackwell_ali_masuodi_egan_muller_2021, title={Detecting pulmonary nodules by using ultrasound multiple scattering}, volume={150}, ISSN={["1520-8524"]}, DOI={10.1121/10.0006666}, abstractNote={Although X-Ray Computed Tomography (CT) is widely used for detecting pulmonary nodules inside the parenchyma, it cannot be used during video-assisted surgical procedures. Real-time, non-ionizing, ultrasound-based techniques are an attractive alternative for nodule localization to ensure safe resection margins during surgery. Conventional ultrasound B-mode imaging of the lung is challenging due to multiple scattering. However, the multiple scattering contribution can be exploited to detect regions inside the lung containing no scatterers. Pulmonary nodules are homogeneous regions in contrast to the highly scattering parenchyma containing millions of air-filled alveoli. We developed a method relying on mapping the multiple scattering contribution inside the highly scattering lung to detect and localize pulmonary nodules. Impulse response matrices were acquired in ex-vivo pig and dog lungs using a linear array transducer to semi-locally investigate the backscattered field. Extracting the multiple-scattering contribution using singular-value decomposition and combining it with a depression detection algorithm allowed us to detect and localize regions with less multiple scattering, associated with the nodules. The feasibility of this method was demonstrated in five ex-vivo lungs containing a total of 20 artificial nodules. Ninety-five percent of the nodules were detected. Nodule depth and diameter significantly correlated with their ex-vivo CT-estimated counterparts (R = 0.960, 0.563, respectively).}, number={6}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Roshankhah, Roshan and Blackwell, John and Ali, Mir H. and Masuodi, Behrooz and Egan, Thomas and Muller, Marie}, year={2021}, month={Dec}, pages={4095–4102} }
 @article{lye_roshankhah_karbalaeisadegh_montgomery_egan_muller_mamou_2021, title={In vivo assessment of pulmonary fibrosis and edema in rodents using the backscatter coefficient and envelope statisticsa)}, volume={150}, ISSN={["1520-8524"]}, DOI={10.1121/10.0005481}, abstractNote={Quantitative ultrasound methods based on the backscatter coefficient (BSC) and envelope statistics have been used to quantify disease in a wide variety of tissues, such as prostate, lymph nodes, breast, and thyroid. However, to date, these methods have not been investigated in the lung. In this study, lung properties were quantified by BSC and envelope statistical parameters in normal, fibrotic, and edematous rat lungs in vivo. The average and standard deviation of each parameter were calculated for each lung as well as the evolution of each parameter with acoustic propagation time within the lung. The transport mean free path and backscattered frequency shift, two parameters that have been successfully used to assess pulmonary fibrosis and edema in prior work, were evaluated in combination with the BSC and envelope statistical parameters. Multiple BSC and envelope statistical parameters were found to provide contrast between control and diseased lungs. BSC and envelope statistical parameters were also significantly correlated with fibrosis severity using the modified Ashcroft fibrosis score as the histological gold standard. These results demonstrate the potential for BSC and envelope statistical parameters to improve the diagnosis of pulmonary fibrosis and edema as well as monitor pulmonary fibrosis.}, number={1}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Lye, Theresa H. and Roshankhah, Roshan and Karbalaeisadegh, Yasamin and Montgomery, Stephanie A. and Egan, Thomas M. and Muller, Marie and Mamou, Jonathan}, year={2021}, month={Jul}, pages={183–192} }
 @article{demi_muller_2021, title={Introduction to the special issue on lung ultrasound}, volume={150}, ISSN={["1520-8524"]}, DOI={10.1121/10.0007274}, abstractNote={The potential of lung ultrasound (LUS) has become manifest in the light of the recent COVID-19 pandemic. The need for a point-of care, quantitative, and widely available assessment of lung condition is critical. However, conventional ultrasound imaging was never designed for lung assessment. This limits LUS to the subjective and qualitative interpretation of artifacts and imaging patterns visible on ultrasound images. A number of research groups have begun to tackle this limitation, and this special issue reports on their most recent findings. Through in silico, in vitro, and in vivo studies (preclinical animal studies and pilot clinical studies on human subjects), the research presented aims at understanding and modelling the physical phenomena involved in ultrasound propagation, and at leveraging these phenomena to extract semi-quantitative and quantitative information relevant to estimate changes in lung structure. These studies are the first steps in unlocking the full potential of lung ultrasound as a relevant tool for lung assessment.}, number={6}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Demi, Libertario and Muller, Marie}, year={2021}, month={Dec}, pages={4151–4154} }
 @article{roshankhah_karbalaeisadegh_greer_mento_soldati_smargiassi_inchingolo_torri_perrone_aylward_et al._2021, title={Investigating training-test data splitting strategies for automated segmentation and scoring of COVID-19 lung ultrasound images}, volume={150}, ISSN={["1520-8524"]}, DOI={10.1121/10.0007272}, abstractNote={Ultrasound in point-of-care lung assessment is becoming increasingly relevant. This is further reinforced in the context of the COVID-19 pandemic, where rapid decisions on the lung state must be made for staging and monitoring purposes. The lung structural changes due to severe COVID-19 modify the way ultrasound propagates in the parenchyma. This is reflected by changes in the appearance of the lung ultrasound images. In abnormal lungs, vertical artifacts known as B-lines appear and can evolve into white lung patterns in the more severe cases. Currently, these artifacts are assessed by trained physicians, and the diagnosis is qualitative and operator dependent. In this article, an automatic segmentation method using a convolutional neural network is proposed to automatically stage the progression of the disease. 1863 B-mode images from 203 videos obtained from 14 asymptomatic individual,14 confirmed COVID-19 cases, and 4 suspected COVID-19 cases were used. Signs of lung damage, such as the presence and extent of B-lines and white lung areas, are manually segmented and scored from zero to three (most severe). These manually scored images are considered as ground truth. Different test-training strategies are evaluated in this study. The results shed light on the efficient approaches and common challenges associated with automatic segmentation methods.}, number={6}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Roshankhah, Roshan and Karbalaeisadegh, Yasamin and Greer, Hastings and Mento, Federico and Soldati, Gino and Smargiassi, Andrea and Inchingolo, Riccardo and Torri, Elena and Perrone, Tiziano and Aylward, Stephen and et al.}, year={2021}, month={Dec}, pages={4118–4127} }
 @article{rosado-mendez_smargiassi_inchingolo_soldati_muller_demi_2021, title={Lung Ultrasound for Treatment of Patients With COVID-19 Please Report Your Settings and Mechanical Index}, volume={40}, ISSN={["1550-9613"]}, DOI={10.1002/jum.15389}, number={1}, journal={JOURNAL OF ULTRASOUND IN MEDICINE}, author={Rosado-Mendez, Ivan M. and Smargiassi, Andrea and Inchingolo, Riccardo and Soldati, Gino and Muller, Marie and Demi, Libertario}, year={2021}, month={Jan}, pages={187–189} }
 @article{du_yousefian_horn_muller_2020, title={Evaluation of Structural Anisotropy in a Porous Titanium Medium Mimicking Trabecular Bone Structure Using Mode-Converted Ultrasonic Scattering}, volume={67}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2019.2963162}, abstractNote={The mode-converted (longitudinal to transverse, L-T) ultrasonic scattering method was utilized to characterize the structural anisotropy of a phantom mimicking the structural properties of trabecular bone. The sample was fabricated using metal additive manufacturing from high-resolution computed tomography (CT) images of a sample of trabecular horse bone with strong anisotropy. Two focused transducers were used to perform the L-T ultrasonic measurements. A normal incidence transducer was used to transmit longitudinal ultrasonic waves into the sample, while the scattered transverse signals were received by an oblique incidence transducer. At multiple locations on the sample, four L-T measurements were performed by collecting ultrasonic scattering from four directions. The amplitude of the root mean square (rms) of the collected ultrasonic scattering signals was calculated for each L-T measurement. The ratios of rms amplitudes for L-T measurements in different directions were calculated to characterize the anisotropy of sample. The results show that the amplitude of L-T converted scattering is highly dependent on the direction of microstructural anisotropy. A strong anisotropy of the microstructure was observed, which coincides with simulation results previously published on the same structure as well as with the anisotropy estimated from the CT images. These results suggest the potential of mode-converted ultrasonic scattering methods to assess the anisotropy of materials with porous, complex structures, including trabecular bone.}, number={5}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Du, Hualong and Yousefian, Omid and Horn, Timothy and Muller, Marie}, year={2020}, month={May}, pages={1017–1024} }
 @article{mohanty_karbalaeisadegh_blackwell_ali_masuodi_egan_muller_2020, title={In Vivo Assessment of Pulmonary Fibrosis and Pulmonary Edema in Rodents Using Ultrasound Multiple Scattering}, volume={67}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2020.3023611}, abstractNote={Idiopathic pulmonary fibrosis (IPF) affects 200 000 patients in the United States of America. IPF is responsible for changes in the micro-architecture of the lung parenchyma, such as thickening of the alveolar walls, which reduces compliance and elasticity. In this study, we verify the hypothesis that changes in the microarchitecture of the lung parenchyma can be characterized by exploiting multiple scattering of ultrasound waves by the alveolar structure. Ultrasound propagation in a highly scattering regime follows a diffusion process, which can be characterized using the diffusion constant. We hypothesize that in a fibrotic lung, the thickening of the alveolar wall reduces the amount of air (compared with a healthy lung), thereby minimizing the scattering events. Pulmonary fibrosis is created in Sprague-Dawley rats by instilling bleomycin into the airway. The rats are studied within 3 weeks after bleomycin administration. Using a 128-element linear array transducer operating at 7.8 MHz, in vivo experimental data are obtained from Sprague-Dawley rats and the transport mean free path (L*) and backscatter frequency shift (BFS) are evaluated. Significant differences (p <; 0.05) in the L* values between control and fibrotic rats and in the BFS values between fibrotic and edematous rats showcase the potential of these parameters for diagnosis and monitoring of IPF.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Mohanty, Kaustav and Karbalaeisadegh, Yasamin and Blackwell, John William and Ali, Mir Hasnain and Masuodi, Behrooz and Egan, Thomas and Muller, Marie}, year={2020}, month={Nov}, pages={2274–2280} }
 @article{mohanty_roshankhah_ulrich_muller_2020, title={Lesion Imaging and Target Detection in Multiple Scattering (LITMUS) Media}, volume={67}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2020.2990704}, abstractNote={We present an ultrasound algorithm [lesion imaging and target detection in multiple scattering (LITMUS)] suited to image lesions (hypoechoic) or targets (hyperechoic) in highly complex structures. In such media, standard ultrasound imaging techniques fail to detect lesions or targets due to aberrations and the loss of linearity between propagation distance and propagation time, caused by multiple scattering of ultrasound waves. The present algorithm (LITMUS) has the capability to predict the location as well as the size of such lesions/targets by using the multiple scattered ultrasound signals to its advantage. In this experimental and computational study, we use an ultrasound linear array. Lesions/targets are embedded at varying depths inside multiple scattering media with varying density of scatterers. In the simulations, plastic scatterers are used as the source of multiple scattering in a propagation medium (water). In the experiments, melamine sponges are used, with air alveoli as the scattering source. For multiple locations along the transducer, the incoherent backscattered intensity of the backscattered signals is extracted and the linear growth of the diffusive halo over time is tracked. Sudden changes in this growth indicate the presence of a region with reduced heterogeneity, indicative of the presence of a lesion/target. This methodology is combined with a depression detection algorithm to predict the size and location of the lesion/targets with high fidelity, despite the presence of strong heterogeneity and multiple scattering.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Mohanty, Kaustav and Roshankhah, Roshan and Ulrich, Micah and Muller, Marie}, year={2020}, month={Nov}, pages={2281–2290} }
 @misc{demi_egan_muller_2020, title={Lung Ultrasound Imaging, a Technical Review}, volume={10}, ISSN={["2076-3417"]}, DOI={10.3390/app10020462}, abstractNote={Lung ultrasound (LUS) is a growing and fascinating field of application for ultrasound imaging. Despite the difficulties in imaging an organ largely filled with air, the potential benefits originating from an effective ultrasound method focusing on monitoring and diagnosing lung diseases represent a tremendous stimulus for research in this direction. This paper presents a technical review where, after a brief historical overview, the current limitations of LUS imaging are discussed together with a description of the physical phenomena at stake. Next, the paper focuses on the latest technical developments of LUS.}, number={2}, journal={APPLIED SCIENCES-BASEL}, author={Demi, Libertario and Egan, Thomas and Muller, Marie}, year={2020}, month={Jan} }
 @article{nandi_mohanty_nellenbach_erb_muller_brown_2020, title={Ultrasound Enhanced Synthetic Platelet Therapy for Augmented Wound Repair}, volume={6}, ISSN={["2373-9878"]}, DOI={10.1021/acsbiomaterials.9b01976}, abstractNote={Native platelets perform a number of functions within the wound healing process, including interacting with fibrin fibers at the wound site to bring about retraction after clot formation. Clot retraction improves clot stability and enhances the function of the fibrin network as a provisional matrix to support cellular infiltration of the wound site, thus facilitating tissue repair and remodeling after hemostasis. In cases of traumatic injury or disease, platelets can become depleted and this process disrupted. To that end, our lab has developed synthetic platelet-like particles (PLPs) that recapitulate the clot retraction abilities of native platelets through a Brownian-wrench driven mechanism that drives fibrin network densification and clot retraction over time, however, this Brownian-motion driven process occurs on a longer time scale than native active actin/myosin-driven platelet-mediated clot retraction. We hypothesized that a combinatorial therapy comprised of ultrasound stimulation of PLP motion within fibrin clots would facilitate a faster induction of clot retraction on a more platelet-mimetic time scale and at a lower dosage than required for PLPs acting alone. We found that application of ultrasound in combination with a subtherapeutic dosage of PLPs resulted in increased clot density and stiffness, improved fibroblast migration in vitro and increased epidermal thickness and angiogenesis in vivo, indicating that this combination therapy has potential to facilitate multiphase pro-healing outcomes. Additionally, while these particular studies focus on the role of ultrasound in enhancing specific interactions between fibrin-binding synthetic PLPs embedded within fibrin networks, these studies have wide applicability in understanding the role of ultrasound stimulation in enhancing multi-scale colloidal interactions within fibrillar matrices.}, number={5}, journal={ACS BIOMATERIALS SCIENCE & ENGINEERING}, author={Nandi, Seema and Mohanty, Kaustav and Nellenbach, Kimberly and Erb, Mary and Muller, Marie and Brown, Ashley C.}, year={2020}, month={May}, pages={3026–3036} }
 @article{yu_demi_muller_zhou_2020, title={Ultrasound Imaging: A Silent Hero in COVID-19 and Lung Diagnostics}, volume={67}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2020.3031444}, abstractNote={In the wake of the novel coronavirus (COVID-19) pandemic, the world has been engaged in a protracted battle against a deadly infectious disease. As of October 2020, the COVID-19 virus has struck over 37 million people globally and has taken over 1 million lives. Since the onset of the COVID-19 outbreak, ultrasound imaging has played a major role in facilitating primary diagnosis and in managing the comorbidities of COVID-19 patients. As compared to other medical imaging tools, ultrasound is distinguished in its versatility, portability, and cost-effectiveness. Accordingly, ultrasound has been widely deployed as a point-of-care modality in emergency medicine and in critical care for diagnosing the respiratory health of COVID-19 patients. In addition to its use in COVID-19 diagnostics, ultrasound imaging has gained significant interest in recent years in other areas of lung diagnostics. Nowadays, lung ultrasound researchers are actively devising new algorithms, techniques, and hardware to enhance ultrasound's diagnostic value in lung clinics.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Yu, Alfred C. H. and Demi, Libertario and Muller, Marie and Zhou, Qifa}, year={2020}, month={Nov}, pages={2194–2196} }
 @article{karbalaeisadegh_yousefian_iori_raum_muller_2019, title={Acoustic diffusion constant of cortical bone: Numerical simulation study of the effect of pore size and pore density on multiple scattering}, volume={146}, ISSN={["1520-8524"]}, DOI={10.1121/1.5121010}, abstractNote={While osteoporosis assessment has long focused on the characterization of trabecular bone, the cortical bone micro-structure also provides relevant information on bone strength. This numerical study takes advantage of ultrasound multiple scattering in cortical bone to investigate the effect of pore size and pore density on the acoustic diffusion constant. Finite-difference time-domain simulations were conducted in cortical microstructures that were derived from acoustic microscopy images of human proximal femur cross sections and modified by controlling the density (Ct.Po.Dn) ∈ [ 5 − 25 ] p ore / m m 2 and size (Ct.Po.Dm) ∈ [ 30 − 100 ] μ m of the pores. Gaussian pulses were transmitted through the medium and the backscattered signals were recorded to obtain the backscattered intensity. The incoherent contribution of the backscattered intensity was extracted to give access to the diffusion constant D. At 8 MHz, significant differences in the diffusion constant were observed in media with different porous micro-architectures. The diffusion constant was monotonously influenced by either pore diameter or pore density. An increase in pore size and pore density resulted in a decrease in the diffusion constant (D = 285.9 C t . Po . D m − 1.49 , R 2 = 0.989 , p = 4.96 × 10 − 5 , RMSE = 0.06 ; D = 6.91 C t . Po . D n − 1.01 , R 2 = 0.94 , p = 2.8 × 10 − 3 , RMSE = 0.09), suggesting the potential of the proposed technique for the characterization of the cortical microarchitecture.}, number={2}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Karbalaeisadegh, Yasamin and Yousefian, Omid and Iori, Gianluca and Raum, Kay and Muller, Marie}, year={2019}, month={Aug}, pages={1015–1023} }
 @article{mohanty_yousefian_karbalaeisadegh_ulrich_grimal_muller_2019, title={Artificial neural network to estimate micro-architectural properties of cortical bone using ultrasonic attenuation: A 2-D numerical study}, volume={114}, ISBN={1879-0534}, DOI={10.1016/j.compbiomed.2019.103457}, abstractNote={The goal of this study is to estimate micro-architectural parameters of cortical porosity such as pore diameter (φ), pore density (ρ) and porosity (ν) of cortical bone from ultrasound frequency dependent attenuation using an artificial neural network (ANN). First, heterogeneous structures with controlled pore diameters and pore densities (mono-disperse) were generated, to mimic simplified structure of cortical bone. Then, more realistic structures were obtained from high resolution CT scans of human cortical bone. 2-D finite-difference time-domain simulations were conducted to calculate the frequency-dependent attenuation in the 1-8 MHz range. An ANN was then trained with the ultrasonic attenuation at different frequencies as the input feature vectors while the output was set as the micro-architectural parameters (pore diameter, pore density and porosity). The ANN is composed of three fully connected dense layers with 24, 12 and 6 neurons, connected to the output layer. The dataset was trained over 6000 epochs with a batch size of 16. The trained ANN exhibits the ability to predict the micro-architectural parameters with high accuracy and low losses. ANN approaches could potentially be used as a tool to help inform physics-based modelling of ultrasound propagation in complex media such as cortical bone. This will lead to the solution of inverse-problems to retrieve bone micro-architectural parameters from ultrasound measurements for the non-invasive diagnosis and monitoring osteoporosis.}, journal={COMPUTERS IN BIOLOGY AND MEDICINE}, author={Mohanty, Kaustav and Yousefian, Omid and Karbalaeisadegh, Yasamin and Ulrich, Micah and Grimal, Quentin and Muller, Marie}, year={2019}, month={Nov} }
 @article{rus_melchor_muller_khan_2019, title={Biomechanical Constitutive Model Identification}, volume={2019}, ISSN={["1563-5147"]}, DOI={10.1155/2019/3607015}, journal={MATHEMATICAL PROBLEMS IN ENGINEERING}, author={Rus, Guillermo and Melchor, Juan and Muller, Marie and Khan, Akhtar A.}, year={2019}, month={Jul} }
 @article{yousefian_karbalaeisadegh_muller_2019, title={Modeling ultrasound attenuation in porous structures with mono-disperse random pore distributions using the independent scattering approximation: a 2D simulation study}, volume={64}, ISSN={["1361-6560"]}, DOI={10.1088/1361-6560/ab2a32}, abstractNote={The validity of the independent scattering approximation (ISA) to predict the frequency dependent attenuation in 2D models of simplified structures of cortical bone is studied. Attenuation of plane waves at central frequencies ranging from 1 to 8 MHz propagating in structures with mono-disperse random pore distributions with pore diameter and pore density in the range of those of cortical bone are evaluated by finite difference time domain numerical simulations. An approach to assess the multiple scattering of waves in random media is discussed to determine the pore diameter ranges at which the ISA is applicable. A modified version of the ISA is proposed to more accurately predict the attenuation in porosity ranges where it would traditionally fail. The results show that the modified ISA can model the frequency-dependent attenuation of ultrasonic wave with pore diameter and density ranges comparable to those of cortical bone.}, number={15}, journal={PHYSICS IN MEDICINE AND BIOLOGY}, author={Yousefian, Omid and Karbalaeisadegh, Yasamin and Muller, Marie}, year={2019}, month={Aug} }
 @article{mohanty_yousefian_karbalaeisadegh_ulrich_muller_2019, title={Predicting Structural Properties of Cortical Bone by Combining Ultrasonic Attenuation and an Artificial Neural Network (ANN): 2-D FDTD Study}, volume={11662}, ISBN={["978-3-030-27201-2"]}, ISSN={["1611-3349"]}, DOI={10.1007/978-3-030-27202-9_37}, abstractNote={The goal of this paper is to predict the micro-architectural parameters of cortical bone such as pore diameter (ϕ) and porosity (ν) from ultrasound attenuation measurements using an artificial neural network (ANN). Slices from a 3-D CT scan of human femur are obtained. The micro-architectural parameters of porosity such as average pore size and porosity are calculated using image processing. When ultrasound waves propagate in porous structures, attenuation is observed due to scattering. Two-dimensional finite-difference time-domain simulations are carried out to obtain frequency dependent attenuation in those 2D structures. An artificial neural network (ANN) is then trained with the input feature vector as the frequency dependent attenuation and output as pore diameter (ϕ) and porosity (ν). The ANN is composed of one input layer, 3 hidden layers and one output layer, all of which are fully connected. 340 attenuation data sets were acquired and trained over 2000 epochs with a batch size of 32. Data was split into train, validation and test. It was observed that the ANN predicted the micro-architectural parameters of the cortical bone with high accuracies and low losses with a minimum R2 (goodness of fit) value of 0.95. ANN approaches could potentially help inform the solution of inverse-problems to retrieve bone porosity from ultrasound measurements. Ultimately, those inverse-problems could be used for the non-invasive diagnosis and monitoring of osteoporosis.}, journal={IMAGE ANALYSIS AND RECOGNITION, ICIAR 2019, PT I}, author={Mohanty, Kaustav and Yousefian, Omid and Karbalaeisadegh, Yasamin and Ulrich, Micah and Muller, Marie}, year={2019}, pages={407–417} }
 @article{mohanty_papadopoulou_newsome_shelton_dayton_muller_2019, title={Ultrasound multiple scattering with microbubbles can differentiate between tumor and healthy tissue in vivo}, volume={64}, ISSN={["1361-6560"]}, DOI={10.1088/1361-6560/ab1a44}, abstractNote={Most solid tumors are characterized by highly dense, isotropic vessel networks. Characterization of such features has shown promise for early cancer diagnosis. Ultrasound diffusion has been used to characterize the micro-architecture of complex media, such as bone and the lungs. In this work, we examine a non-invasive diffusion-based ultrasound technique to assess neo-vascularization. Because the diffusion constant reflects the density of scatterers in heterogeneous media, we hypothesize that by injecting microbubbles into the vasculature, ultrasound diffusivity can reflect vascular density (VD), thus differentiating the microvascular patterns between tumors and healthy tissue. The diffusion constant and its anisotropy are shown to be significantly different between fibrosarcoma tumors (n = 16) and control tissue (n = 18) in a rat animal model in vivo. The diffusion constant values for control and tumor were found to be 1.38 ± 0.51 mm2 µs-1 and 0.65 ± 0.27 mm2 µs-1, respectively. These results are corroborated with VD from acoustic angiography (AA) data, confirming increased vessel density in tumors compared to controls. The diffusion constant offers a promising way to quantitatively assess vascular networks when combined with contrast agents, which may allow early tumor detection and characterization.}, number={11}, journal={PHYSICS IN MEDICINE AND BIOLOGY}, author={Mohanty, Kaustav and Papadopoulou, Virginie and Newsome, Isabel G. and Shelton, Sarah and Dayton, Paul A. and Muller, Marie}, year={2019}, month={Jun} }
 @article{mohanty_blackwell_masuodi_ali_egan_muller_2018, title={1-Dimensional quantitative micro-architecture mapping of multiple scattering media using backscattering of ultrasound in the near-field: Application to nodule imaging in the lungs}, volume={113}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.5038005}, DOI={10.1063/1.5038005}, abstractNote={In this letter, we present a near-field method for mapping the micro-architecture of complex media based on the measurement of the diffusion constant D using multiple backscattering of ultrasound waves. Simulation results are reported and validated with experiments. For both simulations and experiments, a linear array of ultrasound transducers is used. The coherent and incoherent intensities are separated using a matrix manipulation of the inter-element response matrix. We demonstrate that no beamforming is necessary to extract the diffusion constant. Acquiring sub-inter-element response matrices by using subsets of elements and calculating the growth of the diffusive halo for each sub-matrix provides an estimate of a semi-local diffusion constant, enabling a 1-D mapping of the scatterer density or volume fraction in a strongly heterogeneous medium. This methodology is then applied to quantitatively characterize the lung parenchyma and detect the presence of solitary pulmonary nodules. The semi-local diffusion constant is mapped along the transducer axis to search for high D values, which correspond to the nodule/lesion location.}, number={3}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Mohanty, Kaustav and Blackwell, John and Masuodi, S. Behrooz and Ali, Mir Hasnain and Egan, Thomas and Muller, Marie}, year={2018}, month={Jul}, pages={033704} }
 @article{joshi_nandi_chester_brown_muller_2018, title={Study of Poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM) Microgel Particle Induced Deformations of Tissue-Mimicking Phantom by Ultrasound Stimulation}, volume={34}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.7b02801}, abstractNote={Poly(N-isopropylacrylamide) (pNIPAm) microgels (microgels) are colloidal particles that have been used extensively for biomedical applications. Typically, these particles are synthesized in the presence of an exogenous cross-linker, such as N,N′-methylenebis(acrylamide) (BIS); however, recent studies have demonstrated that pNIPAm microgels can be synthesized in the absence of an exogenous cross-linker, resulting in the formation of ultralow cross-linked (ULC) particles, which are highly deformable. Microgel deformability has been linked in certain cases to enhanced bioactivity when ULC microgels are used for the creation of biomimetic particles. We hypothesized that ultrasound stimulation of microgels would enhance particle deformation and that the degree of enhancement would negatively correlate with the degree of particle cross-linking. Here, we demonstrate in tissue-mimicking phantoms that using ultrasound insonification causes deformations of ULC microgel particles. Furthermore, the amount of deformation depends on the ultrasound excitation frequency and amplitude and on the concentration of ULC microgel particles. We observed that the amplitude of deformation increases with increasing ULC microgel particle concentration up to 2.5 mg/100 mL, but concentrations higher than 2.5 mg/100 mL result in reduced amount of deformation. In addition, we observed that the amplitude of deformation was significantly higher at 1 MHz insonification frequency. We also report that increasing the degree of microgel cross-linking reduces the magnitude of the deformation and increases the optimal concentration required to achieve the largest amount of deformation. Stimulated ULC microgel particle deformation has numerous potential biomedical applications, including enhancement of localized drug delivery and biomimetic activity. These results demonstrate the potential of ultrasound stimulation for such applications.}, number={4}, journal={LANGMUIR}, author={Joshi, Aditya and Nandi, Seema and Chester, Daniel and Brown, Ashley C. and Muller, Marie}, year={2018}, month={Jan}, pages={1457–1465} }
 @article{yousefian_white_karbalaeisadegh_banks_muller_2018, title={The effect of pore size and density on ultrasonic attenuation in porous structures with mono-disperse random pore distribution: A two-dimensional in-silico study}, volume={144}, ISSN={["1520-8524"]}, DOI={10.1121/1.5049782}, abstractNote={This work proposes a power law model to describe the attenuation of ultrasonic waves in non-absorbing heterogeneous media with randomly distributed scatterers, mimicking a simplified structure of cortical bone. This paper models the propagation in heterogeneous structures with controlled porosity using a two-dimensional finite-difference time domain numerical simulation in order to measure the frequency dependent attenuation. The paper then fits a phenomenological model to the simulated frequency dependent attenuation by optimizing parameters under an ordinary least squares framework. Local sensitivity analysis is then performed on the resulting parameter estimates in order to determine to which estimates the model is most sensitive. This paper finds that the sensitivity of the model to various parameter estimates depends on the micro-architectural parameters, pore diameter (ϕ) and pore density (ρ). In order to get a sense for how confidently model parameters are able to be estimated, 95% confidence intervals for these estimates are calculated. In doing so, the ability to estimate model-sensitive parameters with a high degree of confidence is established. In the future, being able to accurately estimate model parameters from which micro-architectural ones could be inferred will allow pore density and diameter to be estimated via an inverse problem given real or simulated ultrasonic data to be determined.}, number={2}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Yousefian, Omid and White, R. D. and Karbalaeisadegh, Yasamin and Banks, H. T. and Muller, Marie}, year={2018}, month={Aug}, pages={709–719} }
 @article{mohanty_blackwell_egan_muller_2017, title={CHARACTERIZATION OF THE LUNG PARENCHYMA USING ULTRASOUND MULTIPLE SCATTERING}, volume={43}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2017.01.011}, abstractNote={The purpose of the study described here was to showcase the application of ultrasound to quantitative characterization of the micro-architecture of the lung parenchyma to predict the extent of pulmonary edema. The lung parenchyma is a highly complex and diffusive medium for which ultrasound techniques have remained qualitative. The approach presented here is based on ultrasound multiple scattering and exploits the complexity of ultrasound propagation in the lung structure. The experimental setup consisted of a linear transducer array with an 8-MHz central frequency placed in contact with the lung surface. The diffusion constant D and transport mean free path L* of the lung parenchyma were estimated by separating the incoherent and coherent intensities in the near field and measuring the growth of the incoherent diffusive halo over time. Significant differences were observed between the L* values obtained in healthy and edematous rat lungs in vivo. In the control rat lung, L* was found to be 332 μm (±48.8 μm), whereas in the edematous lung, it was 1040 μm (±90 μm). The reproducibility of the measurements of L* and D was tested in vivo and in phantoms made of melamine sponge with varying air volume fractions. Two-dimensional finite difference time domain numerical simulations were carried out on rabbit lung histology images with varying degrees of lung collapse. Significant correlations were observed between air volume fraction and L* in simulation (r = -0.9542, p < 0.0117) and sponge phantom (r = -0.9932, p < 0.0068) experiments. Ex vivo measurements of a rat lung in which edema was simulated by adding phosphate-buffered saline revealed a linear relationship between the fluid volume fraction and L*. These results illustrate the potential of methods based on ultrasound multiple scattering for the quantitative characterization of the lung parenchyma.}, number={5}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Mohanty, Kaustav and Blackwell, John and Egan, Thomas and Muller, Marie}, year={2017}, month={May}, pages={993–1003} }
 @article{meziere_juskova_woittequand_muller_bossy_boistel_malaquin_derode_2016, title={Experimental observation of ultrasound fast and slow waves through three-dimensional printed trabecular bone phantoms}, volume={139}, ISSN={["1520-8524"]}, DOI={10.1121/1.4939297}, abstractNote={In this paper, ultrasound measurements of 1:1 scale three-dimensional (3D) printed trabecular bone phantoms are reported. The micro-structure of a trabecular horse bone sample was obtained via synchrotron x-ray microtomography, converted to a 3D binary data set, and successfully 3D-printed at scale 1:1. Ultrasound through-transmission experiments were also performed through a highly anisotropic version of this structure, obtained by elongating the digitized structure prior to 3D printing. As in real anisotropic trabecular bone, both the fast and slow waves were observed. This illustrates the potential of stereolithography and the relevance of such bone phantoms for the study of ultrasound propagation in bone.}, number={2}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Meziere, F. and Juskova, P. and Woittequand, J. and Muller, M. and Bossy, E. and Boistel, Renaud and Malaquin, L. and Derode, A.}, year={2016}, month={Feb}, pages={EL13–EL18} }
 @article{peralta_mourier_richard_chavette-palmer_muller_tanter_rus_2015, title={117 IN VIVO EVALUATION OF THE CERVICAL STIFFNESS EVOLUTION DURING INDUCED LABOR IN EWES USING ELASTOGRAPHY}, volume={27}, ISSN={1031-3613}, url={http://dx.doi.org/10.1071/RDV27N1AB117}, DOI={10.1071/RDV27N1AB117}, abstractNote={Despite numerous advances and intensive research in perinatal medicine, spontaneous preterm birth (PTB) is the leading global cause of neonatal mortality and morbidity. On the other hand, labour has to be induced in ~23% of pregnancies worldwide. Both issues may be related to the distensibility of the cervical tissue. Quantitative and objective monitoring of the cervix ripening may provide a complementary method to identify cases at risk of PTB and assess the likelihood of successful induction of labour. Currently, however, no reliable clinical tools for such a quantitative and objective evaluation exist. Elastography aims at imaging tissue stiffness. All elastography techniques rely on the same basics: an external force is applied to the tissue and the resulting movements are then followed. Supersonic shear imaging (SSI) is a dynamic method that uses the propagation of mechanical waves to excite the tissue. Its speed is tracked then by ultrafast imaging, allowing characterisation of stiffness [Bercoff et al. 2004 IEEE Trans. Ultrason. Ferroelect. Freq. Contr. 51, 396–409]. Understanding the mechanisms that take place in normal pregnancy will allow a better comprehension of the cervical remodelling and lead to better methods of diagnosis of PTB and successful induction of labour. In this work, we propose a preliminary assessment of the evolution of stiffness during the cervical maturation process in the sheep. The main goal was to study the feasibility of elastography using SSI to quantify cervical stiffness during the maturation process and to assess the potential of this technique for diagnosis of preterm labour and for labour induction success. Cervical stiffness was quantified, by 2 different operators, in 9 pregnant ewes in vivo by using SSI. The cervical ripening was induced by a dexamethasone injection in 5 animals, and 4 animals constituted the control group. The stiffness of the second ring of the cervix was quantified over a circular region of interest of 5 mm of diameter during vaginal ultrasound examination. Images were acquired every 4 h during 24 h to monitor the cervical maturation induced by the dexamethasone injection. Cervical stiffness was found to decrease significantly throughout the cervical ripening (from 9.5 ± 0.9 kPa to 5.0 ± 0.8 kPa; P = 2.7e–5). The intraobserver and interobserver repeatability of measurements were assessed using Bland-Altman analysis with 95% CI. The principal findings of the study were that elastography measurements using SSI technique were highly reproducible in all cases. Second, stiffness of the uterine cervix decreases throughout the maturation process induced by the dexamethasone injection. Finally, it was possible to quantify the decrease of stiffness through the cervical maturation process. Elastography may be a valuable method to quantify objectively and noninvasively the cervical stiffness in vivo, and ultimately could be a useful tool for the diagnosis of PTB and the assessment of labour induction success.}, number={1}, journal={Reproduction, Fertility and Development}, publisher={CSIRO Publishing}, author={Peralta, L. and Mourier, E. and Richard, C. and Chavette-Palmer, P. and Muller, M. and Tanter, M. and Rus, G.}, year={2015}, pages={150} }
 @article{muller_ait-belkacem_hessabi_gennisson_grange_goffinet_lecarpentier_cabrol_tanter_tsatsaris_2015, title={ASSESSMENT OF THE CERVIX IN PREGNANT WOMEN USING SHEAR WAVE ELASTOGRAPHY: A FEASIBILITY STUDY}, volume={41}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2015.06.020}, abstractNote={The quantitative assessment of the cervix is crucial for the estimation of pre-term delivery risk and the prediction of the success of labor induction. We conducted a cross-sectional study using shear wave elastography based on the supersonic shear imaging technique. The shear wave speed (SWS) of the lower anterior part of the cervix was quantified over an 8-mm region of interest in 157 pregnant women. Cervical SWS is slightly but significantly reduced in patients diagnosed with pre-term labor and in patients who actually delivered pre-term.}, number={11}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Muller, Marie and Ait-Belkacem, Dora and Hessabi, Mahdieh and Gennisson, Jean-Luc and Grange, Gilles and Goffinet, Francois and Lecarpentier, Edouard and Cabrol, Dominique and Tanter, Mickael and Tsatsaris, Vassilis}, year={2015}, month={Nov}, pages={2789–2797} }
 @inproceedings{meziere_bossy_derode_juskova_woittequand_malaquin_muller_2015, title={Bone phantoms for the observation of the fast and slow waves}, DOI={10.1109/esucb.2015.7169914}, abstractNote={Working with bone mimicking phantoms is necessary for the development of ultrasonic methods for bone characterization. The phantoms currently available for trabecular bone do not mimic some of the bone ultrasonic properties accurately. We report the fabrication of anisotropic phantoms, constituted of square rods, using a modified stereolithographic printer. Ultrasound pulse propagation was performed in the phantoms and the fast and slow waves could be observed for a propagation along the main orientation of the rods. This work demonstrates the feasibility of printing anisotropic structures with a typical size comparable to the size of bone trabeculae. Further work will be directed towards high resolution printing of full trabecular micro-structures.}, booktitle={2015 6th European Symposium on Ultrasonic Characterization of Bone (ESUCB)}, author={Meziere, F. and Bossy, E. and Derode, A. and Juskova, P. and Woittequand, J. and Malaquin, L. and Muller, M.}, year={2015} }
 @article{cassereau_mézière_muller_bossy_derode_2015, title={Computation of the Diffracted Field by an Elliptic Rigid or Elastic Scatterer: An Overview of the Numerical Limitations}, volume={70}, ISSN={1875-3892}, url={http://dx.doi.org/10.1016/J.PHPRO.2015.08.133}, DOI={10.1016/J.PHPRO.2015.08.133}, abstractNote={Abstract In this paper, we are interested in the 2D computation of the pressure scattered by an elliptic scatterer using a semi-analytical method based on a decomposition of the solutions on a basis of cylindrical waves. This approach is perfectly adapted to circular scatterers, and has been extended to scatterers of arbitrary shape [F. Chati et al. (2004)]. We will see that this extended formulation yields some very difficult numerical issues, particularly in our context of a flat and small elliptic scatterer. The use of arbitrary precision mathematics appears as a possible workaround, even if the cost in terms of the computation time may be prohibitive.}, journal={Physics Procedia}, publisher={Elsevier BV}, author={Cassereau, Didier and Mézière, Fabien and Muller, Marie and Bossy, Emmanuel and Derode, Arnaud}, year={2015}, pages={208–212} }
 @article{peralta_mourier_richard_charpigny_larcher_ait-belkacem_balla_brasselet_tanter_muller_et al._2015, title={In Vivo Evaluation of Cervical Stiffness Evolution during Induced Ripening Using Shear Wave Elastography, Histology and 2 Photon Excitation Microscopy: Insight from an Animal Model}, volume={10}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0133377}, abstractNote={Prematurity affects 11% of the births and is the main cause of infant mortality. On the opposite case, the failure of induction of parturition in the case of delayed spontaneous birth is associated with fetal suffering. Both conditions are associated with precocious and/or delayed cervical ripening. Quantitative and objective information about the temporal evolution of the cervical ripening may provide a complementary method to identify cases at risk of preterm delivery and to assess the likelihood of successful induction of labour. In this study, the cervical stiffness was measured in vivo in pregnant sheep by using Shear Wave Elastography (SWE). This technique assesses the stiffness of tissue through the measurement of shear waves speed (SWS). In the present study, 9 pregnant ewes were used. Cervical ripening was induced at 127 days of pregnancy (term: 145 days) by dexamethasone injection in 5 animals, while 4 animals were used as control. Elastographic images of the cervix were obtained by two independent operators every 4 hours during 24 hours after injection to monitor the cervical maturation induced by the dexamethasone. Based on the measurements of SWS during vaginal ultrasound examination, the stiffness in the second ring of the cervix was quantified over a circular region of interest of 5 mm diameter. SWS was found to decrease significantly in the first 4-8 hours after dexamethasone compared to controls, which was associated with cervical ripening induced by dexamethasone (from 1.779 m/s ± 0.548 m/s, p < 0.0005, to 1.291 m/s ± 0.516 m/s, p < 0.000). Consequently a drop in the cervical elasticity was quantified too (from 9.5 kPa ± 0.9 kPa, p < 0.0005, to 5.0 kPa ± 0.8 kPa, p < 0.000). Moreover, SWE measurements were highly reproducible between both operators at all times. Cervical ripening induced by dexamethasone was confirmed by the significant increase in maternal plasma Prostaglandin E2 (PGE2), as evidenced by the assay of its metabolite PGEM. Histological analyses and two-photon excitation microscopy, combining both Second Harmonic Generation (SHG) and Two-photon Fluorescence microscopy (2PF) contrasts, were used to investigate, at the microscopic scale, the structure of cervical tissue. Results show that both collagen and 2PF-active fibrillar structures could be closely related to the mechanical properties of cervical tissue that are perceptible in elastography. In conclusion, SWE may be a valuable method to objectively quantify the cervical stiffness and as a complementary diagnostic tool for preterm birth and for labour induction success.}, number={8}, journal={PLOS ONE}, author={Peralta, Laura and Mourier, Eve and Richard, Christophe and Charpigny, Gilles and Larcher, Thibaut and Ait-Belkacem, Dora and Balla, Naveen K. and Brasselet, Sophie and Tanter, Mickael and Muller, Marie and et al.}, year={2015}, month={Aug} }
 @article{gennisson_muller_gabor_frydman_musset_tanter_ami_2015, title={Quantification of elasticity changes in the myometrium during labor using Supersonic Shear Imaging: A feasibility study}, volume={56}, ISSN={0041-624X}, url={http://dx.doi.org/10.1016/J.ULTRAS.2014.07.013}, DOI={10.1016/J.ULTRAS.2014.07.013}, abstractNote={Very little is known about the myometrium's physiology in terms of its elasticity but shear wave elastography could be an efficient tool to better understand it. This could considerably help the prevention of difficult births, the consequences of which are tremendous for neonate morbidity and pathologies. The purpose of this paper is to show the feasibility of the in vivo monitoring of myometrial stiffness changes in contraction and relaxation during pregnancy. In this study, Supersonic Shear Wave Imaging, a real-time and quantitative imaging technique that has been proven efficient for the investigation of tissue elasticity, was used to quantify the uterus shear-wave speed and stiffness in 6 patients, through the abdomen, using an 8-MHz linear ultrasound probe. Changes in shear wave speed were tracked in real time during the uterine contraction and were well correlated with the uterine pressure, which is currently considered to be a gold standard. These results open a new way to better understand the myometrium contraction during labour.}, journal={Ultrasonics}, publisher={Elsevier BV}, author={Gennisson, Jean-Luc and Muller, Marie and Gabor, Petra and Frydman, René and Musset, Dominique and Tanter, Mickaël and Ami, Olivier}, year={2015}, month={Feb}, pages={183–188} }
 @article{mézière_muller_bossy_derode_2014, title={Measurements of ultrasound velocity and attenuation in numerical anisotropic porous media compared to Biot’s and multiple scattering models}, volume={54}, ISSN={0041-624X}, url={http://dx.doi.org/10.1016/J.ULTRAS.2013.09.013}, DOI={10.1016/J.ULTRAS.2013.09.013}, abstractNote={This article quantitatively investigates ultrasound propagation in numerical anisotropic porous media with finite-difference simulations in 3D. The propagation media consist of clusters of ellipsoidal scatterers randomly distributed in water, mimicking the anisotropic structure of cancellous bone. Velocities and attenuation coefficients of the ensemble-averaged transmitted wave (also known as the coherent wave) are measured in various configurations. As in real cancellous bone, one or two longitudinal modes emerge, depending on the micro-structure. The results are confronted with two standard theoretical approaches: Biot's theory, usually invoked in porous media, and the Independent Scattering Approximation (ISA), a classical first-order approach of multiple scattering theory. On the one hand, when only one longitudinal wave is observed, it is found that at porosities higher than 90% the ISA successfully predicts the attenuation coefficient (unlike Biot's theory), as well as the existence of negative dispersion. On the other hand, the ISA is not well suited to study two-wave propagation, unlike Biot's model, at least as far as wave speeds are concerned. No free fitting parameters were used for the application of Biot's theory. Finally we investigate the phase-shift between waves in the fluid and the solid structure, and compare them to Biot's predictions of in-phase and out-of-phase motions.}, number={5}, journal={Ultrasonics}, publisher={Elsevier BV}, author={Mézière, Fabien and Muller, Marie and Bossy, Emmanuel and Derode, Arnaud}, year={2014}, month={Jul}, pages={1146–1154} }
 @article{maresca_emmer_van neer_vos_versluis_muller_de jong_van der steen_2010, title={Acoustic Sizing of an Ultrasound Contrast Agent}, volume={36}, ISSN={0301-5629}, url={http://dx.doi.org/10.1016/j.ultrasmedbio.2010.06.014}, DOI={10.1016/j.ultrasmedbio.2010.06.014}, abstractNote={Because the properties of ultrasound contrast agent populations after administration to patients are largely unknown, methods able to study them noninvasively are required. In this study, we acoustically performed a size distribution measurement of the ultrasound contrast agent Definity®. Single lipid-shelled microbubbles were insonified at 25 MHz, which is considerably higher than their resonance frequency, so that their acoustic responses depended on their geometrical cross sections only. We calculated the size of each microbubble from their measured backscattered pressures. The acoustic size measurements were compared with optical reference size measurements to test their accuracy. Our acoustic sizing method was applied to 88 individual Definity® bubbles to derive a size distribution of this agent. The size distribution obtained acoustically showed a mean diameter (2.5 μm) and a standard deviation (0.9 μm) in agreement within 8% with the optical reference measurement. At 25 MHz, this method can be applied to bubble sizes larger than 1.2 μm in diameter. It was observed that similar sized bubbles can give different responses (up to a factor 1.5), probably because of shell differences. These limitations should be taken into account when implementing the method in vivo. This acoustic sizing method has potential for estimating the size distribution of an ultrasound contrast agent noninvasively. (E-mail: [email protected] )}, number={10}, journal={Ultrasound in Medicine & Biology}, publisher={Elsevier BV}, author={Maresca, David and Emmer, Marcia and van Neer, Paul L.M.J. and Vos, Hendrik J. and Versluis, Michel and Muller, Marie and de Jong, Nico and van der Steen, Antonius F.W.}, year={2010}, month={Oct}, pages={1713–1721} }
 @article{muller_gennisson_deffieux_tanter_fink_2009, title={Quantitative Viscoelasticity Mapping of Human Liver Using Supersonic Shear Imaging: Preliminary In Vivo Feasability Study}, volume={35}, ISSN={0301-5629}, url={http://dx.doi.org/10.1016/j.ultrasmedbio.2008.08.018}, DOI={10.1016/j.ultrasmedbio.2008.08.018}, abstractNote={This paper demonstrates the feasibility of in vivo quantitative mapping of liver viscoelasticity using the concept of supersonic shear wave imaging. This technique is based on the combination of a radiation force induced in tissues by focused ultrasonic beams and a very high frame rate ultrasound imaging sequence capable of catching in real time the transient propagation of resulting shear waves. The local shear wave velocity is recovered using a dedicated time-of-flight estimation technique and enables the 2-D quantitative mapping of shear elasticity. This imaging modality is performed using a conventional ultrasound probe during a standard intercostal ultrasonographic examination. Three supersonic shear imaging (SSI) sequences are applied successively in the left, middle and right parts of the 2-D ultrasonographic image. Resulting shear elasticity images in the three regions are concatenated to provide the final image covering the entire region-of-interest. The ability of the SSI technique to provide a quantitative and local estimation of liver shear modulus with a millimetric resolution is proven in vivo on 15 healthy volunteers. Liver moduli extracted from in vivo data from healthy volunteers are consistent with those reported in the literature (Young's modulus ranging from 4 to 7.5 kPa). Moreover, liver stiffness estimation using the SSI mode is shown to be fast (less than one second), repeatable (5.7% standard deviation) and reproducible (6.7% standard deviation). This technique, used as a complementary tool for B-mode ultrasound, could complement morphologic information both for fibrosis staging and hepatic lesions imaging.}, number={2}, journal={Ultrasound in Medicine & Biology}, publisher={Elsevier BV}, author={Muller, Marie and Gennisson, Jean-Luc and Deffieux, Thomas and Tanter, Mickaël and Fink, Mathias}, year={2009}, month={Feb}, pages={219–229} }
 @article{muller_mitton_talmant_johnson_laugier_2008, title={Nonlinear ultrasound can detect accumulated damage in human bone}, volume={41}, ISSN={0021-9290}, url={http://dx.doi.org/10.1016/j.jbiomech.2007.12.004}, DOI={10.1016/j.jbiomech.2007.12.004}, abstractNote={Bone micro-damage is commonly accepted as a relevant parameter for fracture risk assessment, but there is no available technique for its non-invasive characterization. The objective of this work is to study the potential of nonlinear ultrasound for damage detection in human bone. Ultrasound is particularly desirable due to its non-invasive and non-ionizing characteristics. We show results illustrating the correlation of progressive fatigue of human bone samples to their nonlinear dynamical response. In our experiments, damage was induced in 30 samples of diaphyseal human femur using fatigue cycling. At intervals in the cycling, the nonlinear response of the samples was assessed applying Nonlinear Resonant Ultrasound Spectroscopy (NRUS). The nonlinear parameter alpha, which in other materials correlates with the quantity of damage, dramatically increased with the number of mechanical testing cycles. We find a large spread in alpha in the pristine samples and infer that the spread is due to damage differences in the sample population. As damage accumulates during cycling, we find that alpha is much more sensitive to damage than other quantities measured, including the slope and hysteresis of the load/displacement curve, and the dynamic wavespeed. To our knowledge, this study represents the first application of the concept of nonlinear dynamic elasticity to human bone. The results are promising, suggesting the value of further work on this topic. Ultimately, the approach may have merit for in vivo bone damage characterization.}, number={5}, journal={Journal of Biomechanics}, publisher={Elsevier BV}, author={Muller, M. and Mitton, D. and Talmant, M. and Johnson, P. and Laugier, P.}, year={2008}, pages={1062–1068} }
 @article{muller_mitton_moilanen_bousson_talmant_laugier_2008, title={Prediction of bone mechanical properties using QUS and pQCT: Study of the human distal radius}, volume={30}, ISSN={1350-4533}, url={http://dx.doi.org/10.1016/j.medengphy.2007.08.006}, DOI={10.1016/j.medengphy.2007.08.006}, abstractNote={The objective was to compare the prediction of bone mechanical properties provided by axial transmission to that provided by peripheral quantitative computed tomography (pQCT) at the distal radius. The distal radius is the location for Colles' fractures, a common osteoporosis related trauma situation. Measurements of the radial speed of sound were performed using three axial transmission devices: a commercial device (Sunlight Omnisense, 1.25 MHz), a bi-directional axial transmission prototype (1 MHz), both measuring the velocity of the first arriving signal (FAS), and a low frequency (200 kHz) device, measuring the velocity of a slower wave. Co-localized pQCT measurements of bone mineral density and cortical thickness were performed. Ultrasound and pQCT parameters were compared to mechanical parameters such as failure load and Young's modulus, obtained using quasistatic compressive mechanical testing and finite elements modelling (FEM). Correlations of the ultrasound and pQCT parameters to mechanical parameters were comparable. The best predictor of failure load was the pQCT measured cortical thickness. The best predictor of Young's modulus was the bi-directional SOS. The low frequency device significantly correlated to cortical thickness and failure load. The results suggest that different axial transmission approaches give access to different bone mechanical parameters. The association of different axial transmission techniques should be able to provide a good prediction of bone mechanical parameters, and should therefore be helpful for fracture risk prediction.}, number={6}, journal={Medical Engineering & Physics}, publisher={Elsevier BV}, author={Muller, M. and Mitton, D. and Moilanen, P. and Bousson, V. and Talmant, M. and Laugier, P.}, year={2008}, month={Jul}, pages={761–767} }
 @article{tanter_bercoff_athanasiou_deffieux_gennisson_montaldo_muller_tardivon_fink_2008, title={Quantitative Assessment of Breast Lesion Viscoelasticity: Initial Clinical Results Using Supersonic Shear Imaging}, volume={34}, ISSN={0301-5629}, url={http://dx.doi.org/10.1016/j.ultrasmedbio.2008.02.002}, DOI={10.1016/j.ultrasmedbio.2008.02.002}, abstractNote={This paper presents an initial clinical evaluation of in vivo elastography for breast lesion imaging using the concept of supersonic shear imaging. This technique is based on the combination of a radiation force induced in tissue by an ultrasonic beam and an ultrafast imaging sequence capable of catching in real time the propagation of the resulting shear waves. The local shear wave velocity is recovered using a time-offlight technique and enables the 2-D mapping of shear elasticity. This imaging modality is implemented on a conventional linear probe driven by a dedicated ultrafast echographic device. Consequently, it can be performed during a standard echographic examination. The clinical investigation was performed on 15 patients, which corresponded to 15 lesions (4 cases BI-RADS 3, 7 cases BI-RADS 4 and 4 cases BI-RADS 5). The ability of the supersonic shear imaging technique to provide a quantitative and local estimation of the shear modulus of abnormalities with a millimetric resolution is illustrated on several malignant (invasive ductal and lobular carcinoma) and benign cases (fibrocystic changes and viscous cysts). In the investigated cases, malignant lesions were found to be significantly different from benign solid lesions with respect to their elasticity values. Cystic lesions have shown no shear wave propagate at all in the lesion (because shear waves do not propage in liquid). These preliminary clinical results directly demonstrate the clinical feasibility of this new elastography technique in providing quantitative assessment of relative stiffness of breast tissues. This technique of evaluating tissue elasticity gives valuable information that is complementary to the B-mode morphologic information. More extensive studies are necessary to validate the assumption that this new mode potentially helps the physician in both false-positive and false-negative rejection.}, number={9}, journal={Ultrasound in Medicine & Biology}, publisher={Elsevier BV}, author={Tanter, Mickael and Bercoff, Jeremy and Athanasiou, Alexandra and Deffieux, Thomas and Gennisson, Jean-Luc and Montaldo, Gabriel and Muller, Marie and Tardivon, Anne and Fink, Mathias}, year={2008}, month={Sep}, pages={1373–1386} }
 @article{muller_tencate_darling_sutin_guyer_talmant_laugier_johnson_2006, title={Bone micro-damage assessment using non-linear resonant ultrasound spectroscopy (NRUS) techniques: A feasibility study}, volume={44}, ISSN={0041-624X}, url={http://dx.doi.org/10.1016/j.ultras.2006.06.043}, DOI={10.1016/j.ultras.2006.06.043}, abstractNote={Non-linear resonant ultrasound spectroscopy (NRUS) is a technique exploiting the significant non-linear behavior of damaged materials, related to the presence of damage. This study shows for the first time the feasibility of this technique for damage assessment in bone. Two samples of bovine cortical bone were subjected to a progressive damage experiment. Damage accumulation was progressively induced in the samples by mechanical testing. For independent assessment of damage, X-ray CT imaging was performed at each damage step, but only helped in the detection of the prominent cracks. Synchrotron micro-CT imaging and histology using epifluorescence microscopy were performed in one of the two samples at the last damage step and allowed detection of micro-cracks for this step. As the quantity of damage accumulation increased, NRUS revealed a corresponding increase in the non-linear response. The measured change in non-linear response is much more sensitive than the change in elastic modulus . The results suggest that NRUS could be a potential tool for micro-damage assessment in bone. Further work has to be carried out for a better understanding of the physical nature of damaged bone, and for the ultimate goal of in vivo implementation of the technique where bone access will be a challenging problem.}, journal={Ultrasonics}, publisher={Elsevier BV}, author={Muller, M. and Tencate, J.A. and Darling, T.W. and Sutin, A. and Guyer, R.A. and Talmant, M. and Laugier, P. and Johnson, P.A.}, year={2006}, month={Dec}, pages={e245–e249} }
 @article{muller_moilanen_bosisio_mitton_talmant_2006, title={Comparison of ultrasonic axial transmission and pQCT parameters to bone mechanical properties in vitro}, volume={39}, ISSN={0021-9290}, url={http://dx.doi.org/10.1016/S0021-9290(06)84849-9}, DOI={10.1016/S0021-9290(06)84849-9}, journal={Journal of Biomechanics}, publisher={Elsevier BV}, author={Muller, M. and Moilanen, P. and Bosisio, M. and Mitton, D. and Talmant, M.}, year={2006}, month={Jan}, pages={S452} }
 @article{muller_d'hanens_mitton_talmant_johnson_laugier_2006, title={Fatigue damage in cortical bone detected using nonlinear ultrasound}, volume={39}, ISSN={0021-9290}, url={http://dx.doi.org/10.1016/S0021-9290(06)82896-4}, DOI={10.1016/S0021-9290(06)82896-4}, journal={Journal of Biomechanics}, publisher={Elsevier BV}, author={Muller, M. and D'Hanens, A. and Mitton, D. and Talmant, M. and Johnson, P. and Laugier, P.}, year={2006}, month={Jan}, pages={S8} }
 @article{muller_moilanen_bossy_nicholson_kilappa_timonen_talmant_cheng_laugier_2005, title={Comparison of three ultrasonic axial transmission methods for bone assessment}, volume={31}, ISSN={0301-5629}, url={http://dx.doi.org/10.1016/j.ultrasmedbio.2005.02.001}, DOI={10.1016/j.ultrasmedbio.2005.02.001}, abstractNote={This study compared three approaches to bone assessment using ultrasonic axial transmission. In 41 fresh human radii, velocity of the first arriving signal was measured with a commercial device (Sunlight Omnisense) operating at 1.25 MHz, a prototype based on 1-MHz bidirectional axial transmission and a low-frequency (200 kHz) prototype, also measuring the velocity of a slower wave. Cortical and trabecular bone mineral density, cortical thickness and cross-sectional area were determined by peripheral quantitative computed tomography. Significant but modest correlation between velocities reflects differences in the nature of the propagating waves and methodological differences. Of the higher frequency devices, bidirectional measurements provided stronger correlations with bone properties than did conventional measurements. High-frequency devices were less sensitive to cortical thickness than was the low-frequency device, because higher frequency waves interrogate thinner cortical layers. The results suggest that different axial transmission approaches reflect different bone properties. Therefore, a multifrequency technique might be useful in probing different bone properties.}, number={5}, journal={Ultrasound in Medicine & Biology}, publisher={Elsevier BV}, author={Muller, M. and Moilanen, P. and Bossy, E. and Nicholson, P. and Kilappa, V. and Timonen, J. and Talmant, M. and Cheng, S. and Laugier, P.}, year={2005}, month={May}, pages={633–642} }