Ultrasonic Imaging System Research Articles

Design and Evaluation of a Weighted Periodic Sparse Array for Low-Complexity 1-D Phased Array Ultrasound Imaging Systems.

A sparse array offers a significant reduction in the complexity of ultrasonic imaging systems by decreasing the number of active elements and associated electrical circuits needed to form a focused beam. Consequently, for 1-D arrays, it has been adopted in the development of miniaturized systems such as portable, handheld, or smartphone-based systems. Previously, we developed an analytic method that can design a pair of 1-D periodic sparse arrays (PSAs) satisfying three specific constraints, which are the array size, desired grating lobe level, and sparseness factor (SF). In this study, we further developed our method by incorporating aperture weighting functions, which take the form of tapered rectangular functions to introduce null points on the beam pattern. These null points effectively suppress grating lobes generated by a matching pair of arrays. The design process commences with determining transmit and receive PSA patterns, followed by deriving corresponding aperture weighting functions. First, aperture functions of a base and weighting arrays are convolved, which is then upsampled to the targeted array size. Finally, the upsampled aperture is convolved to an aperture function of a subarray, resulting in weighted PSAs (wPSAs). Pulsed wave (PW) simulation confirmed improved grating lobe suppression with wPSAs compared to PSAs. Phantom imaging experiments using a 1-D phased array validated the enhanced contrast due to suppressed grating lobes but at the cost of small degradation in lateral resolution. The signal-to-noise ratio (SNR) also gradually declined with the greater SFs, but no significant difference in SNR was observed between wPSAs and PSAs. Finally, in vivo echocardiography imaging highlighted the clinical potential of wPSAs, particularly with high SFs. Overall, these results suggest that wPSAs can effectively enhance contrast compared to PSAs under the given SF or, alternatively, wPSA with greater SFs can achieve comparable image quality to PSAs with lower SFs. In conclusion, the wPSA approach holds promise for further reducing the complexity of ultrasound imaging systems.

A Study of Mechanical Scanning High-frequency Ultrasonic Color Flow Imaging

Abstract High-frequency Ultrasonic imaging can promote high-resolution images and detailed diagnostic information, which has great clinical application prospects. However, due to the difficulty and high cost of high-frequency multi-channel ultrasound systems and multi-array element transducers, it is not conducive to popularization. Mechanical scanning high-frequency ultrasound imaging system is an alternative and low-cost method. However, current mechanical scanning systems cannot perform ultrasound flow imaging, and hemodynamic information is clinically important. Therefore, an improved high-frequency, miniaturized mechanical scanning system for color flow imaging was designed and developed. The system uses a crank linkage structure to drive a miniature transducer with a center frequency of 12 MHz for reciprocating scanning imaging within a range of 15 mm. By optimizing the clutter filter and dynamic domain flow imaging process, two methods are realized: real-time rapid ultrasound imaging and highly sensitive ultrasound flow imaging. The two optimized methods used power Doppler and color flow Doppler for flow phantom imaging, and the final measured blood flow error was less than 5%, which indicates that the mechanical scanning high-frequency ultrasonic color flow imaging system has a good application prospect.

A Miniature PMUT Array for Medical Applications

Abstract Wearable continuous monitoring technology and internal and cerebrovascular imaging are the frontier hot area of current scientific research, which are of great significance to improving human life and health. Ultrasonic imaging can obtain information such as deep tissue structure by transmitting ultrasonic waves into the tissue and detecting echo signals, and ultrasonic imaging technology has the advantages of high imaging depth, high resolution, high safety, fast and convenient, etc. It is one of the important technologies in the medical field such as wearable continuous monitoring technology and internal cardiovascular and cerebrovascular imaging. But miniaturization and low power consumption are necessary conditions for the success of such medical applications. Therefore, the ultrasonic imaging technology using a miniature ultrasonic probe is one of the most promising imaging technologies for this type of medical application. Aiming at the common technical problems of traditional ultrasonic transducers such as large volume, narrow bandwidth, high power consumption, difficulty in preparing two-dimensional arrays, and difficulty in integrating with ICs. In this paper, the electromechanical-acoustic multi-field coupling mechanism and array structure design technology of MEMS high-performance PMUT ultrasonic transducer elements are first studied, and a CMOS-compatible miniature PMUT high-performance array ultrasonic device suitable for this type of medical application is developed. The simulation results of the transducer are given. The measurement of various physical parameters of the transducer sample and the results of its application in the ultrasonic imaging system show that the miniature PMUT linear array ultrasonic sensor we designed is a kind of high performance ultrasonic array sensors that can be widely used in wearable continuous monitoring technology and internal cardiovascular and cerebrovascular imaging.

The Development of Spinal Endoscopic Ultrasonic Imaging System with an Automated Tissue Recognition Algorithm.

Preclinical experimental study. To develop an intraoperative ultrasound-assisted imaging device, which could be placed at the surgical site through an endoscopic working channel and which could help surgeon recognition of different tissue types during endoscopic spinal surgery (ESS). ESS remains a challenging task for spinal surgeons. Great proficiency and experience are needed to perform procedures such as intervertebral discectomy and neural decompression within a narrow channel. The limited surgical view poses a risk of damaging important structures, such as nerve roots. We constructed a spinal endoscopic ultrasound system, using a 4-mm custom ultrasound probe, which can be easily inserted through the ESS working channel, allowing up to 10 mm depth detection. This system was applied to ovine lumbar spine samples to obtain ultrasound images. Subsequently, we proposed a two-stage classification algorithm, based on a pretrained DenseNet architecture for automated tissue recognition. The recognition algorithm was evaluated using accuracy and consistency. The probe can be easily used in the ESS working channel and produce clear and characteristic ultrasound images. We collected 367 images for training and testing of the recognition algorithm, including images of the spinal cord, nucleus pulposus, adipose tissue, bone, annulus fibrosus and nerve roots. The algorithm achieved over 90% accuracy in recognizing all types of tissues with a Kappa value of 0.875. The recognition times were under 0.1 s using the current configuration. Our system was able to be used in existing ESS working channels and clearly identified at-risk spinal structures in vitro. The pretrained algorithms could identify six intraspinal tissue types accurately and quickly. The concept and innovative application of intraoperative ultrasound in ESS may shorten the learning curve of ESS and improve surgical efficiency and safety.

A CONCEPTUAL MODELING OF ULTRASONIC TOMOGRAPHY SYSTEM TO DETECT EARLY CARIES LESIONS

Dental diagnostic imaging plays a significant role in the field of dentistry. In the oral environment, continuous demineralization and remineralization of tooth structure is common. Early diagnosis and monitoring of carious lesions are essential, and enamel abnormalities require quantitative imaging techniques. Among the imaging modalities available are radiography, X-ray computed tomography, and magnetic resonance imaging. However, to obtain imaging information on dental diagnostics, most of these systems rely on specific radiation and energy which might be harmful to health. To overcome the aforementioned problem, this research proposes a conceptual modeling of ultrasonic tomography system to detect enamel abnormalities using simulation from COMSOL software. Ultrasonic tomography can be obtained by the presence of acoustic waves transmitted from a source and the reflection of the waves at the investigated area. The transmission technique yielded 0.0041260 V for 7 MHz and 0.0003841 V for 25 MHz, but the reflection method yielded 0.000060 V for 7 MHz and 0.000211 V for 25 MHz. The transmission approach produces the greatest difference in voltage when compared to the reflection method. This suggests that, in comparison to the reflection technique, the transmission method is significantly better at detecting changes on the tooth surface.

Single-Bit Reception With Coded Excitation for Lightweight Advanced Ultrasonic Imaging Systems.

The demand for an efficient and reliable ultrasonic phased array imaging system is not unique to a single industry. Today's imaging systems can be enhanced in a number of areas including; improving scanning and processing times, reducing data storage requirements, simplifying hardware, and prolonging probe lifespan. In this work, it is shown that by combining the use of coded excitation with single-bit data capture, a number of these areas can be improved. Despite using single-bit receive data, resolution can be recovered through the coded excitation pulse compression process, and shown to produce high signal-to-noise ratio (SNR) images of phase coherence imaging (PCI) and total focusing method (TFM) of tip diffraction in a carbon steel sample. Comparison with conventional single-cycle transmission pulses has shown that little imaging performance degradation is seen despite a significant reduction in data resolution and size. This has also been shown to be effective at low excitation voltages with gain compensation due to the obsolescence of signal saturation concerns when considering single-bit receive data. The ability to compute high-resolution ultrasonic images from low-resolution input data at low transmission voltages has important implications for data compression, acquisition and imaging performance, operator safety, and hardware simplification for ultrasonic imaging systems across industrial and medical fields.

Development of Wireless Ultrasonic Device for Wireless Guided-Wave Ultrasonic Propagation Imaging System

Development of Wireless Ultrasonic Device for Wireless Guided-Wave Ultrasonic Propagation Imaging System

Demonstration of an ultrasonic imaging system for molten lead

2D and 3D ultrasonic imaging has so far not been demonstrated in pure molten lead in the open literature. In this study the development of such an ultrasonic device for imaging is outlined and results from testing at 380 °C in lead are presented. The main difficulties were found to be achieving then maintaining suitable wetting while ensuring suitable durability of the device, both due to the harsh nature of molten lead and the elevated temperatures. The successful detection and imaging (2D and 3D), of differently shaped targets, where the features were above the size of the transmitted ultrasound beam was demonstrated.

Variability in Cross-Sectional Muscle Atrophy: Insights From the Central Rectus Femoris.

This study aimed to evaluate the non-uniformity of cross-sectional areas in atrophic musclesusing the central aponeurosis (CA) as a marker for the central region of the rectus femoris (RF). We enrolled 51 consecutively admitted patients (102 limbs) with aortic valve stenosis who were scheduled for elective surgical or catheter-based aortic valve replacement and were expected to have low physical activity-induced muscle atrophy. We obtained short-axis images of the mid-thigh using an ultrasonic diagnostic imaging system (with a 5-cm-wide probe) and measured the deviation of the central region of the rectus femoris from the body surface. Muscle thickness was measured using conventional morphological measurements on the body surface ("On Surface") and landmarks within the ultrasonographic image ("In Images"). Displacements ≥ 1.5 cm were observed in 56 (54.9%) limbs, and displacements ≥ 2.5 cm were observed in 34 (33%) limbs. The displacements were predominantly in the medial direction and ranged from 4 cm to 1.5 cm. Among the cases in which the deviation was ≥2.5 cm, "On Surface" measurements resulted in images in which the vastus lateralis overlapped with the rectus femoris. The thickness of the rectus femoris was significantly lower with "On Surface" measurements than with "In Images" measurements (right, p < 0.001; left, p = 0.007), with a maximum difference of 10.5 mm. In conclusion, it was observed that the rectus femoris at the center was often displaced medially, and the muscle thickness was thinner at the edge than at the center, showing a non-uniform morphology.

Spatially resolved readout of a Fabry-Perot ultrasound sensor interrogated through a multimode optical fiber using wavefront shaping.

The spatially resolved interrogation of a Fabry-Perot ultrasound sensor using a laser beam focused through a multimode fiber is demonstrated. To scan the beam across the sensor as required to read it out, optical wavefront shaping was employed to compensate for the scrambling of light in the fiber. By providing a means to map ultrasound through inexpensive, lightweight fibers, this could lead to new ultrasonic and photoacoustic imaging systems, such as endoscopes and flexible handheld probes.

Simulations and experimentation of ultrasonic wave propagation and flaw characterisation for underwater concrete structures

ABSTRACT Ultrasonic non-destructive evaluation of concrete submerged in water is a complex phenomenon that has important implications for the durability and safety of marine structures such as bridges, piers and offshore platforms. The scattering of ultrasonic waves inside concrete materials with aggregate size comparable to the ultrasound wavelength often limits the interpretation of inspection results. To enhance the understanding of ultrasonic wave propagation inside the underwater concrete, numerical simulations using the finite element method (FEM) with the Transient Acoustics-Piezoelectric Interaction application mode of Multiphysics software package have been developed. This study focuses on developing a 2D numerical model to reproduce and illustrate the propagation of ultrasound in seven types of underwater concrete test blocks with various types of inclusions and voids embedded inside it. The B-Scan 2D images of the concrete test blocks were acquired using the simulated data and compared with experimental results acquired using an in-house developed four-channel ultrasonic imaging system. Both simulation and experimental results showed a good resemblance, indicating that B-Scan imaging can be applied to identify and characterise various types of defects and inclusions in underwater concrete structures, providing better assessment of the material than conventional ultrasonic pulse velocity (UPV) method.

Physical and dynamic characteristics of high-amplitude ultrasonic wave propagation in nonlinear and dissipative media

This study presents a comprehensive investigation into the soliton solutions for the Khokhlov–Zabolotskaya–Kuznetsov ([Formula: see text]) problem using the Bernoulli sub-equation function approach, generalized Kudryashov method, and Homotopy perturbation method. The [Formula: see text] equation, a nonlinear wave equation that governs the propagation of high-amplitude ultrasonic waves through nonlinear media, is studied in detail. Perturbation theory and asymptotic expansions are employed to derive approximate solutions for the [Formula: see text] problem. These methodologies offer valuable insights into the behavior of ultrasonic waves in different media, thereby facilitating the optimization of ultrasonic transducer design and enhancing the precision of ultrasonic imaging systems. The analytical and semi-analytical methods utilized for solving the [Formula: see text] equation are computationally efficient and serve as valuable resources for researchers and engineers working in the field of ultrasonics. The outcomes of this study carry significant implications for the understanding of ultrasonic wave behavior in nonlinear and dissipative media, ultimately contributing to the development of more accurate and efficient ultrasonic imaging techniques.

A Freehand 3D Ultrasound Reconstruction Method Based on Deep Learning

In the medical field, 3D ultrasound reconstruction can visualize the internal structure of patients, which is very important for doctors to carry out correct analyses and diagnoses. Furthermore, medical 3D ultrasound images have been widely used in clinical disease diagnosis because they can more intuitively display the characteristics and spatial location information of the target. The traditional way to obtain 3D ultrasonic images is to use a 3D ultrasonic probe directly. Although freehand 3D ultrasound reconstruction is still in the research stage, a lot of research has recently been conducted on the freehand ultrasound reconstruction method based on wireless ultrasonic probe. In this paper, a wireless linear array probe is used to build a freehand acousto-optic positioning 3D ultrasonic imaging system. B-scan is considered the brightness scan. It is used for producing a 2D cross-section of the eye and its orbit. This system is used to collect and construct multiple 2D B-scans datasets for experiments. According to the experimental results, a freehand 3D ultrasonic reconstruction method based on depth learning is proposed, which is called sequence prediction reconstruction based on acoustic optical localization (SPRAO). SPRAO is an ultrasound reconstruction system which cannot be put into medical clinical use now. Compared with 3D reconstruction using a 3D ultrasound probe, SPRAO not only has a controllable scanning area, but also has a low cost. SPRAO solves some of the problems in the existing algorithms. Firstly, a 60 frames per second (FPS) B-scan sequence can be synthesized using a 12 FPS wireless ultrasonic probe through 2–3 acquisitions. It not only effectively reduces the requirement for the output frame rate of the ultrasonic probe, but also increases the moving speed of the wireless probe. Secondly, SPRAO analyzes the B-scans through speckle decorrelation to calibrate the acousto-optic auxiliary positioning information, while other algorithms have no solution to the cumulative error of the external auxiliary positioning device. Finally, long short-term memory (LSTM) is used to predict the spatial position and attitude of B-scans, and the calculation of pose deviation and speckle decorrelation is integrated into a 3D convolutional neural network (3DCNN). Prepare for real-time 3D reconstruction under the premise of accurate spatial pose of B-scans. At the end of this paper, SPRAO is compared with linear motion, IMU, speckle decorrelation, CNN and other methods. From the experimental results, it can be observed that the spatial pose deviation of B-scans output using SPRAO is the best of these methods.

Ultrasonic subwavelength imaging with blind structured illumination

The resolution of ultrasonic imaging systems suffers from the diffraction limit. To solve this problem, we develop a blind structured illumination microscopy (blind-SIM) system that achieves far-field subwavelength resolution in underwater ultrasonic imaging systems. By illuminating the object with multiple structured illumination (SI) patterns generated by scattering media with subwavelength features, the spatial frequency mixing between the object and the SIs converts evanescent waves to propagate waves that can reach sensors in the far field. In this work, the acoustic SIs are generated by randomly distributed micro particles in water. The image of the object is then reconstructed from multiple measurements (each produced by a SI pattern) utilizing computational reconstruction algorithms where the precise knowledge of the SIs is not required. The developed ultrasonic blind-SIM system has the potential in improving the ultrasonic imaging resolution in medical diagnoses, underwater acoustic imaging, and communications. Our system largely reduces the imaging hardware complexity and improves the imaging speed compared with existing ultrasonic subwavelength technologies that mostly rely on the precise localization of time-varying contrast agents.

Recent Advances in Flexible Ultrasonic Transducers: From Materials Optimization to Imaging Applications.

Ultrasonic (US) transducers have been widely used in the field of ultrasonic and photoacoustic imaging system in recent years, to convert acoustic and electrical signals into each other. As the core part of imaging systems, US transducers have been extensively studied and achieved remarkable progress recently. Imaging systems employing conventional rigid US transducers impose certain constraints, such as not being able to conform to complex surfaces and comfortably come into contact with skin and the sample, and meet the applications of continuous monitoring and diagnosis. To overcome these drawbacks, significant effort has been made in transforming the rigid US transducers to become flexible and wearable. Flexible US transducers ensure self-alignment to complex surfaces and maximize the transferred US energy, resulting in high quality detection performance. The advancement in flexible US transducers has further extended the application range of imaging systems. This review is intended to summarize the most recent advances in flexible US transducers, including advanced functional materials optimization, representative US transducers designs and practical applications in imaging systems. Additionally, the potential challenges and future directions of the development of flexible US transducers are also discussed.

Ultrasonic Phased Array Process Tomography System for Multiphase Medium Imaging

Ultrasonic process tomography (UPT) has great application potential in multiphase flow online monitoring due to its non-invasive, radiation-free and visualization features. Existing UPTs with individual transducers suffer from the small number of projection data, which results in low imaging accuracy. This paper presents a novel modular and scalable UPT system, i.e. an ultrasonic phased array tomography (UPAT) system in a digital and modular design, which includes a master control board and up to eight 16-channel ultrasound transceiver boards that are capable of expanding to 128-channel ultrasound transceivers. The beamformers on each transceiver board can flexibly synthesize the sound beams with adjustable shape and direction, while parallelly collecting and processing 16-channel ultrasound signals. To deal with high amount data transmission, the serial rapid IO (SRIO) data exchange protocol with a maximum bandwidth of 4Gbps is applied between the master board and the transceiver boards. Static imaging experiments with a novel tomographic sensing strategy validates the system performance, where the size and location of complex inclusion distribution are reconstructed at a high spatial resolution. The results show that this UPAT system meets the requirements of multiphase flow online monitoring.

A High-Frequency Mechanical Scanning Ultrasound Imaging System

High-frequency ultrasound has developed rapidly in clinical fields such as cardiovascular, ophthalmology, and skin with its high imaging resolution. However, the development of multi-elements high-frequency ultrasonic transducers and multi-channel high-frequency ultrasound imaging systems is extremely challenging. Here, a high-frequency ultrasound imaging system based on mechanical scanning was proposed in this paper. It adopts the method of reciprocating feed mechanism, which can achieve reciprocating scanning in the 14 mm range at 168 mm/s with a small 60 MHz transducer. A single-channel high-frequency ultrasonic imaging system consisting of the transmitting module, analog front end, acquisition module, and FPGA control module was developed. To overcome the non-uniformity of mechanical scanning, the ultrasound images are compensated according to the motion trajectory. The wire target and ex vivo tissue experiments have shown that the system can obtain an imaging resolution of 51 μm, imaging depth of 8 mm, and imaging speed of 12 fps. This high-frequency mechanical scanning ultrasound imaging system has the characteristics of simple structure, high-frequency, real-time, and good imaging performance, which can meet the clinical needs of high-resolution ultrasound images.

FPGA: Field programmable gate array-based four-channel embedded system for ultrasonic imaging of under-water concrete structures.

Non-destructive testing is needed for the evaluation of quality and safety of concrete structures in the field of civil engineering. The imaging of concrete/reinforced cement concrete structures (RCC) is a challenging task due to the non-homogeneous properties of the concrete material. To address this challenge, a novel real-time, re-configurable, four-channel embedded system has been designed and developed to image the internal details of the concrete samples using the water immersion pulse-echo (PE) mode under automation, which needs access from one side of the structure. The system performs data acquisition (DAQ) of the amplified echo signals under the control of the computer via a universal serial bus interface. A graphical user interface (GUI) has been developed using C# in a Visual environment, for image acquisition and control of the DAQ parameters. The performance of the system has been evaluated by acquiring B-Scan images of three types of concrete test blocks having side drilled holes (SDHs) and simulated inclusions embedded in concrete blocks of M20 grade using a linear array of 92kHz water immersion transducers operating in under-water PE mode. The acquired B-Scan images revealed the internal details of the concrete test blocks with sizing of the SDHs and inclusions. Therefore, the developed four-channel ultrasonic imaging system can visualize the internal details of under-water concrete structures, such as bridges and sea links, with the help of corresponding 2-D cross-sectional images, acquired using the developed system.

Experimental investigation on mechanical behavior of 3D integrated woven spacer composites under quasi-static indentation and compression after indentation: Effect of indenter shapes

This paper presents an experimental study on the mechanical response of 3D integrated woven spacer carbon fiber composites under quasi-static indentation (QSI) and the failure behavior under compression after indentation (CAI). The test specimens are divided into weft direction ones (X-type) and warp direction ones (Y-type). The quasi-static indentation process is conducted using four types of indenters: the hemispherical indenter, the flat indenter, the conical indenter, and the pyramid indenter. A C-scan ultrasonic imaging system and a digital microscope are used to evaluate the damage visibility and penetration resistance of 3D integrated woven spacer composites during the QSI test. The digital image correlation (DIC) is used to perform the CAI analysis. The results indicate that the flat indenter has the largest indentation damage area (395 mm2 for X-type specimens, 398 mm2 for Y-type specimens), and the average indentation damage area caused by the four indenters is less than twice of the maximum cross-sectional area of each indenter. The maximum absorbed energy of two types of 3D integrated woven spacer composites is very similar in QSI tests under the same indenter. It is found that the residual strength of the X-type specimen decreases by 51.7% and that of the Y-type specimen decreases by 35.8% after the flat indenter penetrates the specimen.

Performance Evaluation of an Ultrasonic Imaging System Using Tissue-Mimicking Phantoms for Quality Assurance

Diagnostic ultrasound or sonography is an image that can provide valuable information for diagnosing and treating a variety of diseases and conditions. The aim of this research study is to examine the performance and accuracy of the ultrasonic imaging system for the guarantee of diagnosis quality assurance, and to adjust the penetration settings to minimize the time of repeat scans and maintenance duration during research experiments. Measurements in this experiment included the resolution (axial and lateral) and focal zones. Moreover, the evaluation was done by completing all the measurements at different depths on a multipurpose phantom model 539. The phantom was bought from the market and was not fabricated by the author. The measurements were achieved by applying two different transducers: curved and linear (flat). The ultrasound images were obtained and tested by using calipers (electronic), and the estimations and observations were read by using all the taken measurements and images. As a result, because the phantom depths were different, the penetration settings were different too, indicating that the depth impacted the penetrations of the created ultrasound image. Moreover, after the comparison of the recorded measurements and results, it was found that all measurements were within the accepted (standard) value and that the true value was specified by the production of the phantom.