An innovative processing to deposit poly(vinylidene fluoride–trifluoroethylene) [P(VDF-TrFE)] film on silicon wafers by an inkjet printing method was used to fabricate high-frequency (HF) annular array (AA) prototype. This prototype has a total aperture of 7.3 mm and eight active elements. A polymer-based lens with low acoustic attenuation was added to the flat deposition on the wafer, setting the geometric focus to 13.8 mm. With a thickness of around $11~\mu \text{m}$ , the electromechanical performance of P(VDF-TrFE) films was evaluated with an effective thickness coupling factor of 22%. Electronics allowing all elements to simultaneously emit as a single element transducer was developed. In reception, a dynamic focusing, based on eight independent amplifying channels, was preferred. The center frequency of the prototype was 21.3 MHz, the insertion loss (IL) was 48.5 dB, and the −6-dB fractional bandwidth was 143%. The trade-off sensitivity/bandwidth has rather favored the large bandwidth. Dynamic focusing on reception was applied and allowed to improvements in the lateral full width at half maximum (FWHM) as shown on images obtained with a wire phantom at several depths. The next step, for a fully operational multielement transducer, will be to achieve a significant increase of the acoustic attenuation in the silicon wafer.

We investigated the innovative processing of poly(vinylidene fluoride-trifluoroethylene) P(VDFx-TrFE1-x) (x = 83 mol. %) by inkjet printing to deliver uniform and thickness-controlled layers on silicon substrates. Here, we provide detailed processing steps and optimize film deposition conditions. The thickness coupling factor for a P(VDF-TrFE) film around 11 μm thick was 22%, demonstrating good electromechanical performance after poling. These multilayer structures were specifically for high-frequency, single-element ultrasonic transducer applications. The measurements of electro-acoustic responses were in water. The maximal frequency was centered at 33.2 MHz and had a fine axial resolution at 22 μm, corresponding to a fractional bandwidth at −6 dB of 100%. In the context of technological evolutions aimed at miniaturized devices and integrated electronics, these results allow for the consideration of complex structures such as multi-element transducers for high-frequency imaging applications.

Stroke is the second leading cause of death worldwide. Existing therapies present limitations, and other therapeutic alternatives are sought, such as sonothrombolysis with microbubbles (STL). The aim of this study was to evaluate the change induced by STL with or without recombinant tissue-type plasminogen activator (rtPA) on the acoustic and elastic properties of the blood clot by measuring its sound speed (SoS) and shear wave speed (SWS) with high frequency ultrasound and ultrafast imaging, respectively. An in-vitro setup was used and human blood clots were submitted to a combination of microbubbles and rtPA. The results demonstrate that STL induces a raise of SoS in the blood clot, specifically when combined with rtPA (p < 0.05). Moreover, the combination of rtPA and STL induces a hardening of the clot in comparison to rtPA alone (p < 0.05). This is the first assessment of acoustoelastic properties of blood clots during STL. The combination of rtPA and STL induce SoS and hardening of the clot, which is known to impair the penetration of thrombolytic drugs and their efficacy.

This numerical study compares the acoustic performance of three focalization principles (using a concave piezoelectric element, a lens, or a Fresnel Zone Plate) for a high-frequency (50 MHz) PVDF-based single-element transducer. A pseudo-spectral time-domain method was used to simulate the ultrasound wave propagation in water and to deduce acoustic properties in the focal zone. The focal distance was investigated between 10-20 mm with a step of 1 mm. The external diameter was identical for all configurations and fixed at 6 mm. The results showed a similar behavior between the concave shape and acoustic lens in terms of spatial resolution. However, the comparison showed a significant loss in sensitivity (-22 dB) for the FZP technique mainly due to the large bandwidth at -6 dB (27 MHz) of the electric excitation signal. But, with low bandwidth excitation signal, the simulation showed better performance in the focal zone with FZP transducer and a sensitivity difference with the two others configurations in the range 4.5-8.5 dB.

Transient elastography (TE) is a technique used to quantify Young's Modulus (E) by estimating shear wave velocity in homogenous tissues. This technique has been successfully integrated in the Fibroscan ® device to assess fibrosis stages in liver but has never been validated in the monitoring of skin fibrosis diseases. A specific device based on high-frequency transient elastography (HF-TE) is used to evaluate its performance in case of chronic venous disorder (CVD) diagnosis. E, dermis thickness (DT) and a new parameter, P E - DT , based on a logistic regression model using both E and DT are measured in the dermis of 48 healthy and 48 CVD patients. The discriminant capacity of E, DT and Pe-dt parameters is evaluated with a receiver operating characteristic (ROC) analysis.

Background Microbubbles (MBs) combined with ultrasound sonothrombolysis (STL) appears to be an alternative therapeutic strategy for acute ischemic stroke (IS), but clinical results remain controversial. Objective The aim of this systematic review is to identify the parameters tested; to assess evidence on the safety and efficacy on preclinical data on STL; and to assess the validity and publication bias. Methods Pubmed® and Web of ScienceTM databases were systematically searched from January 1995 to April 2017 in French and English. We included studies evaluating STL on animal stroke model. This systematic review was conducted in accordance with the PRISMA guidelines. Data were extracted following a pre-defined schedule by two of the authors. The CAMARADES criteria were used for quality assessment. A narrative synthesis was conducted. Results Sixteen studies met the inclusion criteria. The result showed that ultrasound parameters and types of MBs were heterogeneous among studies. Numerous positive outcomes on efficacy were found, but only four studies demonstrated superiority of STL versus recombinant tissue-type plasminogen activator on clinical criteria. Data available on safety are limited. Limitations Quality assessment of the studies reviewed revealed a number of biases. Conclusion Further in vivo studies are needed to demonstrate a better efficacy and safety of STL compared to currently approved therapeutic options. Systematic review registration http://syrf.org.uk/protocols/

Background Surgical margins of melanoma vary from 5 mm to 1 or 2 cm depending on histology thickness (Breslow). This approach usually requires two surgical steps: excisional biopsy and further reexcision according to histology thickness. A previous systematic review showed that measuring melanoma thickness with high-resolution ultrasound imaging equipment correlates well with histological measurement of melanoma thickness. Therefore, we routinely determined tumour sonographic thickness in order to perform surgery as a single step. Objectives To determine the proportion of patients who receive onestep surgery with adequate margins based on sonographic measurement of melanoma thickness and identify the reasons for differences between these two measurements. Materials & Methods A retrospective series of patients with melanoma, in which thickness was measured by ultrasound (20 MHz) from April 2007 to December 2015 prior to surgery. Results Ninety-nine melanomas were treated, of which 78 were removed in a single step with surgical margins based on sonometric thickness measurements; 71 of these (91%, 95% CI: 82-96) did not require reexcision, five had excessive margins, and two had insufficient margins. The correlation between the histometric and sonometric measurements was good; r=0.88. Significant absolute difference between sonometric and histometric measurementswas associated with thickness, ulceration, and size of tumours, based on bivariate analysis. Thickness remained the only significant factor based on multivariate analysis. Conclusions Measuring the thickness of melanoma with high-resolution ultrasound imaging equipment makes it possible to remove the melanoma in a single step with adequate margins in at least 82% of the cases in routine care.

In the field of high-frequency ultrasound imaging (>= 20 MHz), tools for characterizing the performance of imaging systems are lacking. Indeed, commercial phantoms are often inadequate for this frequency range. The development of home-made phantoms on the laboratory scale is often required but is hindered by the difficulty in making very small structures that must be distributed with high accuracy in 3-D space. We propose investigating the use of 3-D photopolymer printing to create resolution and calibration phantoms designed for high-frequency ultrasound imaging. The quality and importance of these phantoms are discussed from the point of view of ultrasound parameters and imaging. First, the compressional wave group velocity, acoustic impedance, and attenuation of six photopolymerized materials were measured using temporal and spectral methods in a substitution experimental setup. Measurements were performed on printed samples using a broadband-focused single-element transducer covering a large frequency range (15-55 MHz). Two 3-D phantoms incorporating different shapes and dimensions were designed and printed. Finally, 3-D acoustic images were obtained using either a mechanically driven single-element transducer or a high-frequency commercial imaging system. Three-dimensional printing enabled us to generate phantoms suitable for high-frequency imaging with complex geometry inclusions and with a surrounding material having acoustic properties close to those of human skin. The calculated SNR between the inclusion and surrounding media is approximately 50 dB. In conclusion, 3-D printing is a useful tool for directly, easily, and rapidly manufacturing ultrasound phantoms for ultrasound imaging system assessments and computational calibration or validation.

Interest in elasticity estimation for thin layers is increasing because of the various potential applications, including dermatology and cosmetology. In this context, we propose a dedicated elastographic system using 1-D high-frequency transient elastography (HF-TE) to estimate the 1-D Young's modulus through the dermis and hypodermis, which are the two human skin layers of interest in this study. An experimental validation of the HF-TE method was first carried out on two homogeneous tissue-mimicking hard and soft phantoms. The Young's modulus values obtained in these phantoms were compared with those obtained by two complementary shear wave propagation techniques: shear wave-induced resonance elastography (SWIRE) and supersonic shear imaging (SSI). A third two-layer thin phantom, with mechanical properties similar to those of skin, was used to validate the ability of HF-TE to distinguish layers and measure elasticity. Finally, preliminary in vivo experiments conducted on forearm and cheek skin revealed the promising performance of HF-TE in measuring elasticity in the dermis and hypodermis.

Background: Neurofibromas (NFs) are benign tumours arising from a nerve sheath, which are present in nearly all patients with neurofibromatosis type 1 (NF1). High-frequency ultrasound (HFU) systems, using frequencies over 20 MHz,were developed to improve visualization of skin tumours by means of increased resolution. Objectives: To describe NFs by using HFU in patients with NF1. Materials & Methods: Anonymized HFU (25-MHz) images of NFs were randomized. Initially, two dermatologist investigators, with experience in HFU imaging of the skin, together described the ultrasound images and established eight criteria for NFs. The same task was then repeated by two other dermatologists, also with experience in HFU imaging of the skin, independently, to establish inter-observer agreement. Results: A total of 108 NFs in 29 patients were included. Superficial and subcutaneous NFs were hypoechoic with a round to spindle shape. Plexiform NFs were ill-defined, consisting of multiple hypoechoic linear zones. Good to excellent inter-observer agreement was found for six of the eight criteria (k>0.6). Conclusion: This is the first series describing HFU skin imaging of NFs in patients with NF1. Lateral extension that may correspond to involvement of an adjacent nerve seems to be specific to NFs.

Thrombosis is a major cause of several diseases, i.e. myocardial infarction, cerebral stroke and pulmonary embolism. Thrombolytic therapies are required to induce fast and efficient recanalization of occluded vessels. To evaluate the in vitro efficacy of these thrombolytic strategies, measuring clot dissolution is essential. This study aimed to evaluate and validate high resolution ultrasound as a tool to assess the exact volume of clots in 3D and in real time during in vitro thrombolytic drug testing. This new method was validated by measuring the effects of concentration range of recombinant tissue type plasminogen activator on a blood clot during complete occlusion or 70% stenosis of a vessel. This study shows that high resolution ultrasound imaging allows for a real-time assessment of the 3D volume of a blood clot with negligible inter- and intra-operator variabilities. The conclusions drawn from this study demonstrate the promising potential of high resolution ultrasound imaging for the in vitro assessment of new thrombolytic drugs.

Introduction La marge d’exerese d’un melanome (0,5, 1 ou 2 cm) depend de son epaisseur maximale mesuree sur lame d’histologie (indice de Breslow). L’exerese du melanome necessite 2 temps operatoires : une exerese sans marge puis une reprise avec les marges adaptees au Breslow. La mesure de l’epaisseur des melanomes en echographie haute resolution (EHR) est bien correlee a l’histologie (revue systematique de la litterature 1980–2007, et quelques series publiees depuis). Nous determinons en EHR l’epaisseur tumorale en soins courants depuis 2007 pour operer les patients en un seul temps. L’objectif principal de cette etude etait de calculer le ratio de patients operes en un seul temps avec les marges adequates selon la mesure preoperatoire de l’epaisseur en EHR. Les objectifs secondaires etaient de calculer la correlation entre les mesures echographiques et histologiques, la valeur predictive du Breslow echographique et de rechercher les causes de discordance entre les mesures echographiques et histologiques. Materiel et methodes Etude prospective incluant les patients ayant eu un melanome cutane dont l’epaisseur a ete mesuree par une echographie cutanee haute resolution (20 MHz) d’avril 2007 a decembre 2015. Resultats L’epaisseur de 99 melanomes a ete mesuree en echographie et en histologie. Treize melanomes ont ete operes sans marges puis repris dans un 2 e temps pour des raisons liees au malade (souhait que le melanome soit enleve de suite). Quatre ont ete operes sur la base de l’epaisseur mesuree sur la biopsie partielle (superieure a l’epaisseur echographique). Quatre-vingt-deux melanomes ont ete operes d’emblee avec des marges d’exerese basees sur la mesure echographique de l’epaisseur du melanome (Fig. 1) et 80 (97,5 %) n’ont pas necessite de reprise. La correlation entre les mesures histologiques et echographiques etait egale a 0,85. Les facteurs de discordance etaient la presence d’une ulceration ( p  100mm 2 ( p p p  = 0,053). En analyse multivariee, l’epaisseur (OR 28, 95 % IC 3–270) et la biopsie prealable ( n  = 52) (OR 5,6, 95 % IC 1,4–22,5) restaient significativement associees a une plus grande discordance. Discussion Cette etude est la premiere a avoir mis en pratique la bonne correlation entre les mesures d’epaisseur en EHR et en histologie pour operer les melanomes en un seul temps. Le risque d’erreur par defaut etait faible (2/82). Le risque d’erreur par exces est un peu plus eleve (4/82), mais discute et accepte par les patients (e.g. enlever un in situ du tronc a 1 cm et pas 0,5 cm, pour eviter de le reprendre si Breslow a 0,3 mm). Les principaux avantages sont le gain de temps medical et de confort pour le patient. La principale limite est l’acces limite aux echographes HR. Conclusion Mesurer l’epaisseur maximale d’un melanome en echographie haute resolution permet de pratiquer son exerese en un temps avec des marges adequates en soins courants.

In ophtalmic ultrasonography, axial B-scans are seriously deteriorated owing to the presence of the crystalline lens. This strongly aberrating medium affects both spatial and contrast resolution and causes important distortions. To deal with this issue, an adapted beamforming (BF) has been developed and experimented with a 20MHz linear array working with a custom US research scanner. The adapted BF computes focusing delays that compensate for crystalline phase aberration, including refraction effects. This BF was tested in vitro by imaging a wire phantom through an eye phantom consisting of a synthetic gelatin lens, shaped according to the unaccommodated state of an adult human crystalline lens, anatomically set up in an appropriate liquid (turpentine) to approach the in vivo velocity ratio. Both image quality and fidelity from the adapted BF were assessed and compared with conventional delay-and-sum BF over the aberrating medium. Results showed 2-fold improvement of the lateral resolution, greater sensitivity and 90% reduction of the spatial error (from 758μm to 76μm) with adapted BF compared to conventional BF. Finally, promising first ex vivo axial B-scans of a human eye are presented.

The transforming growth factor-beta (TGF-β) signalling pathway serves as a critical regulator of cellular differentiation, apoptosis, migration and cell proliferation. TGF-β pathway affects transcription of multiple targets 1. One of these targets is the TGF-β inducible early gene-1 (TIEG1) or KLF10, a member of the Krüppel-like factor (KLF) family of zinc-finger proteins that was first identified in human foetal osteoblasts 2. TIEG1 transcript is rapidly and transiently induced after TGF-β treatment in osteoblasts and acts as a positive regulator of TGF-β signalling 3. TIEG1 activity is essential to exert the effect of TGF-β on cell growth and function 2 and has been show to have a critical role in human bone physiology 4. Several alterations during skin ageing involve TGF-β and other cytokines 5. TGF-β also has a broad effect on soft tissue healing through an impact on cell proliferation, cell migration and extracellular matrix deposition during the healing process 6, 7. However, the expression and function of TIEG1 in human skin remains unknown. Here, we investigated TIEG1 expression in human skin cells and whether its role as a TGF-β mediator is conserved. We also analysed TIEG1 expression after exogenous stress or after skin photoexposure. Experiments were performed on skin biopsies or on normal human fibroblasts (NHF) and normal human keratinocytes (NHK) isolated from human abdominal skin samples. All methods are described in details in Supplementary data. The expression of TIEG1 was first analysed in NHF and NHK at the mRNA and protein levels (Fig. 1). We found that both NHF and NHK expressed TIEG1 at a significant level similar to human osteoblasts (HOB), with a clear detection of TIEG1 mRNA (Fig. 1a), and TIEG1 protein using whole protein extracts (Fig. 1b). TIEG1 expression was then assessed by immunofluorescence on fixed cells, where TIEG1 was found mostly expressed in the nucleus (Fig. 1c). Human skin biopsies immunostaining demonstrated that TIEG1 was expressed in both dermal and epidermal skin compartments in vivo (Fig. 1d). To test whether TIEG1 was induced by TGF-β in human skin cells, NHF and NHK were treated with increasing amounts of TGF-β and levels of TIEG1 mRNA were analysed (Fig. 1e). We found a dose-dependent induction of TIEG1 expression with a peak around 0.4–2 ng/ml of TGF-β for both cell types. TGF-β -dependent TIEG1 induction was also confirmed at the protein level, with a peak expression within 24 h of treatment in NHK, while NHF showed a progressive induction up to 48 h of treatment (Fig. 1f). Next, we hypothesized that TIEG1 might be affected by extrinsic or intrinsic factors distressing the skin, such as photoexposure. To test this idea, TIEG1 mRNA level was analysed by immunostaining of biopsies from 13 young (25 ± 4 years old) and aged donors (64 ± 3 years old) either in sun-exposed or non-exposed areas. Masson's trichrome staining of thin sections from these biopsies confirmed their age status by visualization of a significant decrease in total collagen staining in the dermis (Fig. 2a, green signal). To test the impact of skin photoexposure, the intensity of TIEG1 immunostaining was compared in photoprotected and photoexposed biopsies of both age groups (Fig. 2b). We found a relative TIEG1 signal intensity of 2.6 in photoexposed areas of young donors, a value significantly lower than in photoprotected areas from the same donors that showed a TIEG1 relative signal intensity of 4.0 (Fig. 2c). This result supports the view of TIEG1 being sensitive to factors inducing a stress response in skin cells. Next, we tested the effect of exogenous stress on NHF primary cultures by exposing them to specific UVA and UVB irradiation doses or treatment with hydrogen peroxide (H2O2), one of the ROS deleterious for the cells (Fig. 2d,e). TIEG1 protein expression was assessed at different time points after treatment, and expression levels calculated relative to untreated cells (Fig. 2e). NHF were particularly sensitive to stress induction, with a marked and prolonged decrease of TIEG1 expression shortly after H2O2, UVA and to a lesser extent with UVB treatment (Fig. 2e). Additional experiments can be found in supplementary data. TIEG1 is a mediator of TGF-β pathway with an important function in bone tissue regulation 4. Here, we thoroughly described for the first time TIEG1 expression and regulation in human skin cells. We found that TIEG1 was well expressed in NHF and NHK at the mRNA and at the protein level both in primary cultures and in human skin biopsies. The function of TIEG1 as a TGF-β mediator was also revealed in human skin cells and therefore conserved from bone to skin tissues. TIEG1 expression was decreased after exogenous stress such as UV irradiation or H2O2 treatment on primary cell cultures of NHF and NHK, and we found a correlation between in vivo skin photoexposure and low TIEG1 expression. Because TIEG1 is a positive mediator of TGF-β signalling, our results indicate that photoexposure lowers responsiveness to TGF-β pathway by decreasing TIEG1 expression. Previous reports suggest that UV irradiation blocks cellular responses to TGF-β primarily by down-regulating its receptor expression 5, 8. Here, we describe another mechanism by which stress can affect this multifunctional cytokine that regulates cell growth and differentiation. Our work suggests that TIEG1 might play an essential role for human skin both in dermis and epidermis although functional studies need to be performed in order to support this hypothesis. Scientific support: Mrs de Quéral, Dr. Cauchard, Dr. Leblanc, Mr. Schaeffer, Mrs. Juan, Dr. Rochefort, Dr. Benhamou, Dr. Beauchef, Dr. Pichon, Dr. Georgesco, Dr. Tauveron, Dr. Pittet, Mrs. Descoubes, Mr. D'Andigné and Mr. Perrier. Financial support: Conseil Général Yvelines, Loiret, Indre-et-Loire, l'AgglO, Tour(s)plus, Ministère de l'Economie, Industrie et de l'Emploi and Cosmetic Valley. LS, LC, RK, PM, OJ, CH, FO, HT, EL and SS conceived and designed the study. LS, LC, VL and MM performed the experiments. LS, LC, VL, MM, OJ, CH, PM, FO, EL, HT, RK and SS performed the analysis and revised the manuscript. LC, RK, LS, CH and SS wrote the manuscript. None. Data S1. Materials and methods. Data S2. Results and discussion. Figure S1. Controls for TIEG1 protein detection. Figure S2. TIEG1 is induced by TGF-β in human skin cells. Figure S3. TIEG1 expression is not correlated to aging. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, as ultrasounds (US) propagate about 10% faster than in the surrounding intra-ocular medium. Consequently, it impairs significantly both spatial and contrast resolution of axial B-scans, and in addition causes important distortion, especially on the ocular fundus. In this context, we developed in a previous work [1] an adapted beamforming (BF) free from crystalline lens aberration and implemented it on a custom research scanner, the ECODERM, that works with a 20 MHz linear array. The adapted BF lies on a two point ray tracing approach to compute focusing delays that take into account crystalline lens aberrations including refraction at the interface. Previous in vitro experiments consisting in imaging a wire phantom through a synthetic gelatin lens immersed in a liquid reproducing the in vivo velocity ratio between crystalline lens and surrounding humors have demonstrated the efficiency of this adapted BF when the lens is assumed to be homogeneous. As US velocity inside the lens is known to be non uniform, we have extended our adapted BF to take into account the lens heterogeneity. Interest of this consideration is investigated and demonstrated through an ex vivo experiment on an isolated macaque lens in a similar setup to in vitro experiment.

In the field of high frequency ultrasound imaging (i.e. ≥ 20 MHz) there are few tools for characterizing imaging systems performances. Indeed, for this frequency range, commercial phantoms are often inadequate. We propose to investigate the use of 3D photo-polymer printing in order to make, resolution and tissue mimicking phantoms by using an original process which consist to use the normally removed support material as a surrounding medium. First, density, acoustic impedance, velocity, dispersion of wave phase velocity and attenuation of the two photo-polymer materials were measured by a reflection experimental set-up using a focused single-element transducer in frequency range of 15 MHz to 30 MHz. Then, a 3D phantom model was designed and printed. Finally, 2D and 3D acoustic images are shown by using a mechanically driven single element transducer. In conclusion, 3D printing allowed us to make phantoms adapted for high frequency including homogeneities of arbitrary geometries and surrounding medium with acoustics properties close to the human tissues like skin.

Stroke is the second leading cause of death worldwide (Feigin VL et al. Lancet. 2014; 383: 245 – 255). Since 1995, the only effective treatment for stroke patients has been recombinant tissue plasminogen activator (Group N rt-PSS. N Engl J Med. 1995; 333: 1581 – 1587). rt-PA is characterized by hemorrhagic side-effects which have been shown to affect 6.4 % of patients treated with rt-PA (p < 0.001) as compared with 0.6 % of patients in the placebo control group (Group N rt-PSS. N Engl J Med. 1995; 333: 1581 – 1587). Sonothrombolysis, consisting of ultrasound (US) insonation of the clot in combination with gaseous microbubbles, appears to be a potential therapeutic strategy to improve the favorable outcome of this disease while keeping a good safety profile. However, mechanisms of sonothrombolysis remain unclear today. Recently, Petit et al. (Petit B et al. Ultrasound Med ▶ Fig. 1 Image of a clot without insonification or microbubbles after one hour in a plasma flow circuit (10 cm/s, tube of 1.6mm inner diameter). The clot is full of red blood cells. Scale of 20 μm. ▶ Fig. 2 Image of a clot without insonification or microbubbles after one hour in a plasma flow circuit (10 cm/s, tube of 1.6mm inner diameter). The clot is full of red blood cells. Scale of 40 μm. Pictorial Essay

Transient elastography (TE) is a parametric technique used to quantify Young's modulus (E) by estimating the shear wave (SW) velocity (Vs) in an homogeneous medium. TE has been successfully integrated in the Fibroscan® device to assess fibrosis stages in the liver. Considering the last as homogeneous and elastic, fibrosis is correlated to averaged E at 50 Hz low vibration. In this poster, we present a preliminary study using a new development in TE dedicated to 1D high resolution (HR) estimation of E in thin, heterogeneous and viscoelastic medium such as the skin. The HR TE targets to offer a new elastographic tool to characterize viscoelatic parameters of the human dermis in dermatology and cosmetology.

In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, causing a significant decrease in resolution and distortion effects on axial B-scans. This paper proposes a computationally efficient method to correct the phase aberration arising from the crystalline lens, including refraction effects using a bending ray tracing approach based on Fermat's principle. This method is used as a basis to perform eye-adapted beamforming (BF), with appropriate focusing delays for a 128-element 20-MHz linear array in both emission and reception. Implementation was achieved on an in-house developed experimental ultrasound scanning device, the ECODERM. The proposed BF was tested in vitro by imaging a wire phantom through an eye phantom consisting of a synthetic gelatin lens anatomically set up in an appropriate liquid (turpentine) to approach the in vivo velocity ratio. Both extremes of accommodation shapes of the human crystalline lens were investigated. The performance of the developed BF was evaluated in relation to that in homogeneous medium and compared to a conventional delay-and-sum (DAS) BF and a second adapted BF which was simplified to ignore the lens refraction. Global expectations provided by our method with the transducer array are reviewed by an analysis quantifying both image quality and spatial fidelity, as well as the detrimental effects of a crystalline lens in conventional reconstruction. Compared to conventional array imaging, the results indicated a two-fold improvement in the lateral resolution, greater sensitivity and a considerable reduction of spatial distortions that were sufficient to envisage reliable biometry directly in B-mode, especially phakometry.