This is the first article in a series of two dealing with a matrix approach for aberration quantification and correction in ultrasound imaging. Advanced synthetic beamforming relies on a double focusing operation at transmission and reception on each point of the medium. Ultrasound matrix imaging (UMI) consists in decoupling the location of these transmitted and received focal spots. The response between those virtual transducers form the so-called focused reflection matrix that actually contains much more information than a confocal ultrasound image. In this paper, a time-frequency analysis of this matrix is performed, which highlights the single and multiple scattering contributions as well as the impact of aberrations in the monochromatic and broadband regimes. Interestingly, this analysis enables the measurement of the incoherent input-output point spread function at any pixel of this image. A fitting process enables the quantification of the single scattering, multiple scattering and noise components in the image. From the single scattering contribution, a focusing criterion is defined, and its evolution used to quantify the amount of aberration throughout the ultrasound image. In contrast to the state-of-the-art coherence factor, this new indicator is robust to multiple scattering and electronic noise, thereby providing a contrasted map of the focusing quality at a much better transverse resolution. After a validation of the proof-of-concept based on time-domain simulations, UMI is applied to the in-vivo study of a human calf. Beyond this specific example, UMI opens a new route for speed-of-sound and scattering quantification in ultrasound imaging.
Multiple reflections between transducer and imaged object can naturally occur in ultrasound imaging and other acoustic sensing applications such as sonar. The repeated interaction of the emitted wavefront with the imaged object is traditionally regarded an undesired reverberation artifact, often misinterpreted as fictitious acoustic boundaries. Here we introduce high order reflection pulse-echo (HOPE)-ultrasound, a novel method that leverages high order reflections to improve on several aspects of conventional ultrasound imaging. HOPE is experimentally demonstrated to resolve sub-micrometer fe…
In the context of wireless acoustic power transfer, high intensity focused ultrasound technology aims at the reduction of spreading losses by concentrating the acoustic energy at a specific location. Experiments are performed to determine the impact of nonlinear wave propagation on the spatially resonant conditions in a focused ultrasonic power transfer system. An in-depth analysis is performed to explain the experimental observations. The results show that the efficiency of the energy transfer is reduced as nonlinear effects become more prominent. Furthermore, the position of the maximum volt…
Contactless ultrasound power transfer (UPT) has emerged as one of the promising techniques for wireless power transfer. Physical processes supporting UPT include the vibrations at a transmitting/acoustic source element, acoustic wave propagation, piezoelectric transduction of elastic vibrations at a receiving element, and acoustic-structure interactions at the surfaces of the transmitting and receiving elements. A novel mechanism using a high-intensity focused ultrasound (HIFU) transmitter is proposed for enhanced power transfer in UPT systems. The HIFU source is used for actuating a finite-si…
Twinkling Artifact is a valuable tool in detecting dense objects such as kidney stones, calculi etc., especially when there is no acoustic shadowing and presence of hyperechogenic tissues obstructs visualization. This phenomenon is not completely understood. Different scientific groups have contradictory findings concerning its properties: some of them observed a decrease in Twinkling intensity at elevated pulse repetition frequencies (PRF), while others found Twinkling to be independent from PRF, etc. In this paper we hypothesize that this kind of contradictions can be partially resolved on a…
Imaging of ultrasound specularity at cortical bone interfaces to detect unbalanced remodeling: A preliminary study
Sorbonne Université（索邦大学）；INSERM（法国国家健康与医学研究院）；CNRS（法国国家科学研究中心）；Laboratoire d’Imagerie Biomédicale, LIB（生物成像实验室）；Delft University of Technology（代尔夫特理工大学）
Attenuation of ultrasound waves varies with tissue composition, hence its estimation offers great potential for tissue characterization and diagnosis and staging of pathology. We recently proposed a method that allows to spatially reconstruct the distribution of the overall ultrasound attenuation in tissue based on computed tomography, using reflections from a passive acoustic reflector. This requires a standard ultrasound transducer operating in pulse-echo mode and a calibration protocol using water measurements, thus it can be implemented on conventional ultrasound systems with minor adaptat…
Ultrasonic superresolution images can be generated by means of (super) focusing acoustic beams to subwavelength dimensions or using algorithm-based methods. Here, we demonstrate that ultrasonic pulses which are superfocused by a ball-shaped lens can be used to produce superresolution images. The imaging system is comprised of a circular flat transducer with an operation frequency of $1$ MHz, and a ball lens centered in the beam axis of symmetry. The corresponding wavelength in water is $λ_0 = 1.53$ mm. The system resolution is $0.6λ_0$ in the focal plane at one wavelength away from the lens. T…
Photoacoustic imaging (PAI) is an emerging functional and molecular imaging technology that has attracted much attention in the past decade. Recently, many researchers have used the Vantage Verasonics research system for simultaneous ultrasound (US) and photoacoustic (PA) imaging. This was the motivation to write on the details of US/PA imaging system implementation and characterization using Verasonics platform. We describe the subtle details of US/PA imaging system setup, study the performance parameters of the system, and explain sequencing of the US/PA signal generation and signal amplific…
Fourier transform (FT) spectroscopy is a versatile technique for studying the infrared (IR) optical response of solid-, liquid-, and gas-phase samples. In standard FT-IR spectrometers, a light beam passing through a Michelson interferometer is focused onto a sample with condenser optics. This design enables us to examine relatively small samples, but the large solid angle of the focused infrared beam makes it difficult to analyze angle-dependent characteristics. Here we design and construct a high-precision angle-resolved reflection setup compatible with a commercial FT-IR spectrometer. Our se…
