1,721,025 research outputs found
Spatial-coherence-based beamforming for image quality enhancement in high frame-rate ultrasound imaging
No full textSimulating Ultrasound Fields for 2D Phased-Array Probes Design Optimization
No full textNowadays, ultrasound diagnostic imaging is one of the non-invasive techniques mostly used in the clinical practice. Recent advances in this field have brought to the development of small and portable systems. New bidimensional probes consisting of 2D phased arrays, allow to obtain real-time 3D representations of moving organs and blood vessels anatomy. Being the complexity of such 4D ultrasound imaging systems significantly increased, new challenges concerning electronics integration arise for designers. In this paper a software simulator is described, which has been developed in order to model ultrasound wave generation, pressure field distribution and echoes reception, with the aim to become a useful tool for optimizing the probe design. The paper mainly focuses on linear ultrasound field modeling; preliminary results on non-linear interactions with contrast agents are also here introduced
Texture analysis of ultrasound images obtained with different beamforming techniques and dynamic ranges – a robustness study
Full text linkTexture analysis of medical images gives quantitative information about the tissue characterization for possible pathology discrimination. Ultrasound B-mode images are generated through a process called beamforming. Then, to obtain the final 8-bit image, the dynamic range value must be set. It is currently unknown how different beamforming techniques or dynamic range values may alter the final image texture. We provide here a robustness analysis of first and higher order texture features using six beamforming methods and seven dynamic range values, on experimental phantom and in vivo musculoskeletal images acquired using two different ultrasound research scanners. To investigate the repeatability of the texture parameters, we applied the multivariate analysis of variance (MANOVA) and estimated the intraclass
correlation coefficient (ICC) on the texture features calculated on the B-mode images created with different beamforming methods and dynamic range values. We demonstrated the high repeatability of texture features when varying the dynamic range and showed texture features can differentiate between beamforming methods through a MANOVA analysis, hinting at the potential future clinical application of specific beamformers
The delay multiply and sum beamforming algorithm in ultrasound B-mode medical imaging
Full text linkMost of ultrasound medical imaging systems currently on the market implement standard Delay and Sum (DAS) beamforming to form B-mode images. However, image resolution and contrast achievable with DAS are limited by the aperture size and by the operating frequency. For this reason, different beamformers have been presented in the literature that are mainly based on adaptive algorithms, which allow achieving higher performance at the cost of an increased computational complexity. In this paper, we propose the use of an alternative nonlinear beamforming algorithm for medical ultrasound imaging, which is called Delay Multiply and Sum (DMAS) and that was originally conceived for a RADAR microwave system for breast cancer detection. We modify the DMAS beamformer and test its performance on both simulated and experimentally collected linear-scan data, by comparing the Point Spread Functions, beampatterns, synthetic phantom and in vivo carotid artery images obtained with standard DAS and with the proposed algorithm. Results show that the DMAS beamformer outperforms DAS in both simulated and experimental trials and that the main improvement brought about by this new method is a significantly higher contrast resolution (i.e., narrower main lobe and lower side lobes), which turns out into an increased dynamic range and better quality of B-mode images
A Comparison of Coherence-Based Beamforming Techniques in High Frame-Rate Ultrasound Imaging with Multi-Line Transmission.
No full textOne of the current challenges in ultrasound imaging is achieving higher frame rates, particularly in cardiac applications, where tracking the heart motion and other rapid events can provide potential valuable diagnostic information. The main drawback of ultrasound high frame rate strategies is that usually they partly sacrifice image quality in order to speed-up the acquisition time. In particular, multi-line transmission (MLT), which consists in transmitting multiple ultrasound beams simultaneously in different directions, has been proven able to improve frame rates in echocardiography, unfortunately generating artifacts due to inter-beam crosstalk interferences. This work investigates the possibility to effectively suppress crosstalk artifacts in MLT, while improving image quality by applying beamforming techniques based on backscattered signals spatial coherence. Several coherence-based algorithms (i.e. Short-Lag Filtered Delay Multiply and Sum beamforming, Coherence and Generalized Coherence Factor, Phase and Sign Coherence, non-linear beamforming with p-root compression) are implemented and compared, and their performance trends are evaluated when varying their design parameters. Indeed, experimental results of phantom and in vivo cardiac acquisitions demonstrate that this class of algorithms can provide significant benefits as compared to Delay and Sum, well suppressing artifacts (up to 48.5 dB lower crosstalk) and increasing image resolution (by up to 46.3%) and contrast (by up to 30 dB in terms of contrast ratio, and 12.6% for generalized contrast-to-noise ratio) at the same time.sponsorship: This work was supported in part by the University of Pavia through the Blue Sky Research Project MULTIWAVE. The work of A. Ramalli was supported by the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant under Grant 786027 (ACOUSTIC Project). (University of Pavia through the Blue Sky Research Project MULTIWAVE, European Union|786027, Marie Curie Actions (MSCA)|786027)status: Publishe
A wearable intelligent system for the health of expectant mom's and their childs
No full textIl monitoraggio dello stato di salute del feto anteparto mediante l’analisi della frequenza cardiaca fetale e delle contrazioni uterine (CTG) è, insieme all’ecografia, l’esame standard a cui tutte le donne si sottopongono almeno una volta durante la gravidanza. Tuttavia, la maggior parte dei presidi clinici in cui è effettuato il monitoraggio fetale non hanno a disposizione gli strumenti necessari per un’accurata analisi quantitativa dei segnali CTG, e devono affidarsi alla sola competenza del medico che esamina visivamente il tracciato. Pertanto, in termini di valutazione sull’intera popolazione delle gravidanze, l’affidabilità del monitoraggio anteparto è bassa.
Il problema può essere risolto grazie al progetto di un nuovo sistema per il monitoraggio remoto che consenta alle pazienti di effettuare l’esame in qualunque momento ed in qualunque luogo, ricevendo risposte tempestive ed affidabili sulla condizione del feto. Utilizzando le più recenti tecnologie nei settori dei “textile wearable devices” e dell’ICT, realizzeremo un sistema indossabile, in grado di inviare i segnali ad un centro diagnostico remoto, che combinerà la semplicità e la comodità d’uso con un’elevata affidabilità diagnostica.
Per raggiungere l’obiettivo è nato un progetto che coinvolge ricercatori del Politecnico di Milano, dell’università di Pavia e dell’Università di Napoli, al fine di:
• sviluppare e realizzare un sistema indossabile, costituito da una fascia addominale sensorizzata, per la rilevazione, la pre-elaborazione locale e la trasmissione via telefonia wireless dell’attività del cuore fetale e materno, delle contrazioni uterine e della stima dei movimenti fetali;
• definire e implementare algoritmi per l’analisi di segnali e adattamento a dati di sensori indossabili. La ricerca partirà dalla situazione esistente e potrà portare allo sviluppo di nuovi algoritmi di analisi e per la separazione dei contributi materni e fetali con estrazione di parametri e costruzione di classificatori;
• sviluppo di un database di conoscenze e implementazione di un Web Service per l’analisi remota dei dati;
• esecuzione di test clinici su un campione di soggetti volontari nel terzo trimestre di gravidanza in diverse condizioni (riposo, cammino, attività lavorativa, ecc..). Confronto con registrazioni CTG tradizionali già acquisite con il sistema Tocomat
Two-Channel Real-Time EMG control of a Dexterous Hand Prosthesis
No full textIn this paper a case study is introduced, which assesses the suitability of a newly conceived two-channel myoelectric controller for a multi-fingered hand prosthesis. A PCA-based approach, previously presented by the authors, has been employed to control in real-time an underactuated 16-degrees of freedom robotic hand. A volunteer able-bodied subject was enrolled in this case study to test the system, controlling the prosthesis by means of his forearm EMG signals collected by active surface electrodes and properly processed. Trials have shown that the subject was able to successfully operate the prosthetic hand while performing the three prehensile forms mostly used in daily living activities (i.e. power, precision and lateral grips) and stably grasping several different objects. The experiments demonstrate the possibility to develop a bio-inspired myoelectric hand prosthesis endowed with an intuitive and human-like control system. The validation of the PCA-based EMG controller will be carried on in the near future also with hand amputees
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