Real-time Ultrasonic Imaging Research Articles

An efficient wavenumber algorithm towards real-time ultrasonic full-matrix imaging of multi-layered medium

Ultrasonic full-matrix imaging can sense small defects in non-destructive evaluation using full-matrix capture (FMC). However, the accompanying heavy computational burden limits FMC’s applications, especially for real-time scenarios. Currently, the full-matrix imaging for homogeneous medium has progressively advanced, but these algorithms become inaccurate and inefficient for the multi-layered medium. To overcome this problem, an efficient wavenumber algorithm for ultrasonic full-matrix imaging of multi-layered medium is proposed in this paper. The proposed method utilises wavefield extrapolation to migrate the transmitting and receiving transducers virtually to the interfaces between different layers. It then reconstructs the image of each layer with Stolt interpolation. The proposed method is developed based on a wave model, and thus is more rigorous than the ray-based theory in mathematics. Moreover, the calculation in the wavenumber domain dramatically reduces the computational cost. In comparison with well-established root-mean-square-based total focusing method and extended phase shift migration, the proposed method performed better in terms of imaging quality and efficiency in the simulations and experiments. Specifically, it achieves 6–10 Hz imaging frame rates for ultrasonic full-matrix imaging of multi-layered medium using a 64-element phased array, and may find various real-time imaging applications in practice.

Real-time imaging of immersed fuel-sub assemblies using multi-channel ultrasonic camera.

The novel circular-array based real-time ultrasonic imaging technique using an ultrasonic camera has been proposed in this paper for imaging of a fuel sub-assembly (FSA) of a fast breeder reactor. The developed ultrasonic camera-based system provides real-time images of the top-head region of the FSA in a high-temperature environment. For the circular-array based ultrasonic imaging, the entire circular-array has been divided into the various arcs, and the address-based analog multiplexing scheme has been proposed in such a way that all channels of the specific arc are selected concurrently (transducer excitation, data acquisition, and data processing and transferring). Various data processing algorithms are proposed and implemented for multi-channel ultrasonic data processing in real-time. For the experimentation, the complete 18-channel ultrasonic camera system has been designed, developed, and evaluated in the laboratory. The performance evaluation of the developed circular-array based ultrasonic camera has been shown by acquiring the real-time images of the water-immersed dummy FSA in elevated temperature. Furthermore, both qualitative visualization and quantitative measurements of growth and bowing of the FSA top-head are presented.

Ultrasonic camera: a matrix-based real-time ultrasonic imaging system for immersion applications

The novel matrix-based real-time ultrasonic imaging using an ultrasonic camera for immersion application has been proposed in this paper. The proposed ultrasonic camera provides real-time images of mechanical components and the image size is equal to the field of view of the developed matrix-based transducer assembly. For the matrix-based ultrasonic imaging, the addressing-based analog multiplexing scheme has been proposed in such a way that all channels of the specific row are selected simultaneously such as the transducer excitation, data acquisition, data processing and transferring operations are performed concurrently. Similarly, the same operations are performed for remaining all rows sequentially. The developed ultrasonic camera further supports dynamic on-line reconfiguration of the analog front-end hardware, real-time hardware/software-based data processing and data transfer operation. For the experimentation, the entire matrix-based (5 × 5) ultrasonic imaging system for immersion applications has been designed, developed and evaluated in the laboratory. Here we present the performance evaluation of the developed matrix-based ultrasonic camera system by acquiring the real-time images of the water-immersed mechanical objects.

Application of ultrasound in aggressive angiomyxoma: Eight case reports and review of literature

Aggressive angiomyxoma (AAM) is a rare tumour that often occurs in soft tissues of the female genital tract. Eight cases of AAM are reported in this article, and the clinical features and ultrasound and magnetic resonance imaging (MRI) results of the eight cases are reviewed and summarized. The main complaints of all the patients were palpable and painless masses in the vulva or scrotum. The lesions were mainly located in the vulva, pelvis, and perineal region, with a large scope of involvement. The sonographic features of AAM were characteristic. On sonography, all of the masses were of irregular shape and showed hypoechogenicity, with a heterogeneous inner echotexture. Intratumoural and peritumoural blood flows were detected by colour Doppler imaging. On real-time ultrasonic imaging, prominent deformation of the lesions was observed by compressing the masses with the probe. Some special imaging features were also revealed, including a laminated or swirled appearance of inner echogenicity, and a finger-like or tongue-like growth pattern. On MRI imaging, the lesions showed intermediate-intensity signals and intermediate to high-intensity signals on TI-weighted and T2-weighted sequences. A rapid and uneven enhancement pattern was demonstrated. After the comparison of sonographic features with MRI and pathological findings, we found the relevance of the ultrasonographic characteristics with MRI and histological features of AAM. Ultrasound can be a valuable imaging method for the preoperative diagnosis, evaluation of scope, and follow-up of AAM.

Lossless and lossy modeling of ultrasonic imaging system for immersion applications: Simulation and experimentation

The design, modeling, optimization, and development of the entire ultrasonic imaging system is a complex task which involves an understanding of acoustic physics of transducer, acoustic properties of propagating medium, transmission cables and analog front-end electronics for generating and receiving of ultrasonic signals. Such immersion systems are extensively utilized in non-destructive testing (NDT) application for flaw detection, dimensional measurements, material characterization and many more. This paper presents the one-dimensional simulation modeling of the entire ultrasonic imaging system. For validation purpose, a single channel real-time ultrasonic imaging system has been designed and developed for laboratory application which contains high voltage ultrasonic spike pulser, high voltage protection circuits, ultrasonic receiver amplifiers, co-axial cables and an ultrasonic transducer. Lossless and lossy (low-loss) simulations have been performed for ultrasonic transducer and propagation medium using the transmission line model. Effects of non-ideal, frequency-dependent and non-linear components in high voltage excitation circuit (pulser), the receiver circuit and the effects of cables are also considered for modeling and simulation. Validation results of the entire ultrasonic imaging system provide very close agreement with lossy simulated results.

Design and evaluation of medical ultrasonic adaptive beamforming algorithm implementation on heterogeneous embedded computing platform

Medical ultrasonic imaging has been utilized in a variety of clinical diagnoses for many years. Recently, because of the needs of portable and mobile medical ultrasonic diagnoses, the development of real-time medical ultrasonic imaging algorithms on embedded computing platforms is a rising research direction. Typically, delay-and-sum beamforming algorithm is implemented on embedded medical ultrasonic scanners. Such algorithm is the easiest to implement at real-time frame rate, but the image quality of this algorithm is not high enough for complicated diagnostic cases. As a result, minimum-variance adaptive beamforming algorithm for medical ultrasonic imaging is considered in this paper, which shows much higher image quality than that of delay-and-sum beamforming algorithm. However, minimum-variance adaptive beamforming algorithm is a complicated algorithm with O(n3) computational complexity. Consequently, it is not easy to implement such algorithm on embedded computing platform at real-time frame rate. On the other hand, GPU is a well-known parallel computing platform for image processing. Therefore, embedded GPU computing platform is considered as a potential real-time implementation platform of minimum-variance beamforming algorithm in this paper. By applying the described effective implementation strategies, the GPU implementation of minimum-variance beamforming algorithm performed more than 100 times faster than the ARM implementation on the same heterogeneous embedded platform. Furthermore, platform power consumptions, computation energy efficiency, and platform cost efficiency of the experimental heterogeneous embedded platforms were also evaluated, which demonstrated that the investigated heterogeneous embedded computing platforms were suitable for real-time portable or mobile high-quality medical ultrasonic imaging device constructions.

Hardware and software architectures for computationally efficient three‐dimensional ultrasonic data compression

Ultrasonic industrial and medical imaging applications involve acquisition of large amount of volumetric data in real time. Therefore, data storage becomes critical in many current day applications which utilise ultrasound technology. Compressing the acquired data allows possessing minimal storage and also helps to rapidly transmit information to remote locations for expert analysis. The objective of this study is to design computationally efficient architectures for implementing discrete wavelet transform-based ultrasonic three-dimensional (3D) data compression algorithm on a reconfigurable ultrasonic system-on-chip (SoC) hardware platform. In this study, hardware and software architectures of the 3D ultrasonic compression algorithm are realised using Xilinx Zynq all programmable SoC. This study demonstrates that, compressing 33 MB of experimental ultrasonic 3D data into 0.42 MB (98.7% compression) requires only 84 ms for hardware architecture, and 1 min for software architecture, making both designs highly suitable for real-time ultrasonic imaging applications. Furthermore, the 3D compression is implemented by using Open Computing Language (OpenCL) targeted on Nvidia GT 750M graphical processing unit. OpenCL implementation of ultrasonic 3D compression algorithm completes the execution in <1 sec. This approach provides improved computational performance as that of hardware architecture, and comparable flexibility as that of software implementation.

Filter Based Receive-Side Spatial Compounding for Veterinary Ultrasound B-Mode Imaging

Veterinary ultrasound has been used in a large number of animal husbandry-related circumstances while many corresponding applications also call for the use of ultrasound in human patients. However, veterinary ultrasound images are affected by speckle, an interference pattern that can reduce the quality and contrast of ultrasound images. In this paper, a filter-based receive-side spatial compounding technique for veterinary ultrasound B-Mode imaging is used to create a compounded veterinary B-Mode image based on multiple looks. In particular, filtering in the lateral direction has been proved to be able to preserve the axial information in the sub-bands and to create decorrelation between sub-bands at the expense of some lateral resolution. A new method was proposed to obtain B-Mode IQ data by special veterinary ultrasonic probe. This approach is tested on 275 in-vivo swine. The effect is accomplished in real-time veterinary ultrasonic imaging with a measurable improvement of SNRe. Meanwhile, the speckle and electronic noise in the compounded image have been greatly reduced and smoothed in the visual result.

2D ultrasonic elastography with lateral displacement estimation using statistics.

Ultrasound elastography is the method of obtaining relative stiffness information of biological tissue, which plays an important role in early diagnosis. Generally, a gradient-based strain imaging algorithm assumes that motion only occurs in an axial direction. However, because tissue has different relative stiffness, the scatter presents lateral motion under high freehand compression. Therefore, errors occur in estimating the cross-correlation phase in the calculation window. A 2D elastography algorithm with lateral displacement estimation using statistics was proposed to reduce errors. The new method was investigated through simulation, and the experiment confirmed that errors introduced by lateral tissue movement have been greatly reduced with no sacrifice of real-time ultrasonic imaging quality.

견관절 등척성 수축을 동반한 복부 드로우-인 기법이 젊은 성인의 복근 두께에 미치는 효과

This study was conducted in order to examine whether abdominal draw-in maneuver (ADIM) with isometric shoulder flexion, extension, adduction, and abduction selectively contracted deep abdominal muscles. This study's subjects were 13 males 17 females. In order to evaluate the comparison of effects of ADIM and ADIM with isometric shoulder flexion, extension, adduction and abduction, measurements were made on transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) using a real-time ultrasonic diagnostic imaging system. Each position was repetitively measured three times with a real-time ultrasonic diagnostic imaging system and their mean values were used for analysis. The ADIM with isometric shoulder flexion, extension, adduction and abduction significantly increased the thickness of TrA relative to the ADIM only (p<.05). The ADIM with isometric shoulder abduction significantly increased the thickness of IO compared to the ADIM only (p<.05). The ADIM with isometric shoulder extension and abduction significantly decreased the thickness of EO compared to the ADIM only and the ADIM with isometric shoulder extension significantly decreased the thickness of EO relative to the ADIM with isometric shoulder adduction (p<.05). ADIM with isometric shoulder abduction is an effective method to selectively strengthen deep abdominal muscles and therefore may be employed as an intervention for trunk stabilization.

FPGA-Based Configurable Frequency-Diverse Ultrasonic Target-Detection System

In this paper, we present field-programmable gate-array (FPGA)-based configurable architectures that are able to perform frequency-diverse target detection for real-time ultrasonic imaging. Three design methodologies are explored including the execution of the detection algorithm on an embedded microprocessor, the creation of a dedicated hardware solution, and the use of hardware/software codesign principles. In addition to the design flow, this paper presents the impact of parameter changes on the detection-algorithm performance and FPGA implementation results. Experimental studies show that the proposed configurable systems are able to meet real-time operation requirements, and the algorithm performs robustly.

Dynamically Reconfigurable Architecture Design for Ultrasonic Imaging

Ultrasonic imaging algorithms, including detection and compression, are computationally complex and difficult to implement in hardware for real-time applications. In this paper, we present an ultrasonic reconfigurable subband decomposition processor (RSDP) that can employ wavelet filters for frequency diverse signal processing. This architecture enables parallel implementation of a lifting-based discrete wavelet transform. The configurability of the architecture applies to the selection of wavelet kernels and scales for subband decomposition, thresholding operation for compression, and the postprocessing detection algorithm. The underlying hardware design makes use of the fact that both compression and detection applications share the same algorithm fundamentals. A unified architecture has been designed that implements signal decomposition and reconstruction with forward and inverse discrete wavelet transforms. After the forward transform step, a windowing operation is applied to discriminate frequency bands for target detection. Using the same architecture, a thresholding operation is applied to wavelet coefficients for data compression. The flexibility and the modular design make this reconfigurable architecture an effective and practical solution for real-time ultrasonic imaging applications. The resulting architecture is adaptable, fast, and suitable for a system-on-a-chip implementation that requires minimal logic resources.

Hardware-efficient realization of a real-time ultrasonic target detection system using IIR filters

In this study, we address the increased computational demands of a frequency-diverse ultrasonic target detection system by developing a zero-phase IIR (ZP-IIR) filter. Several ZP-IIR filter types including Chebyshev-I, Chebyshev- II, and Butterworth were analyzed for their detection performance. The 4th-order filters with 8-bit quantized coefficients are shown to improve the flaw-to-clutter ratio by approximately 10 dB. Furthermore, the reduced adder graph algorithm is used for a hardware realization of ZP-IIR filters that does not require any dedicated multipliers. A small number of coefficients inherent to IIR filters and their multiplierless implementation provide efficient architecture suitable for compact, real-time ultrasonic imaging devices.

Performance Evaluation of Displacement Estimators for Real-Time Ultrasonic Strain and Blood Flow Imaging With Improved Spatial Resolution

Ultrasonic strain and blood flow imaging has great potential to improve early tumor detection. Both methods have the same task of estimating echo signal displacements. To be able to resolve tissue stiffness and vascularity of tumors while they are still small, spatial resolution must be improved. Moreover, ultrasonic real-time imaging is vital in clinical practice. In this paper, we evaluate the estimation performances of one novel and several established displacement estimators with real-time capability and compare these with results from cross-correlation-based standard estimators when echo signals that are typically available with a commercial ultrasound scanner set to yield the highest spatial resolution are used. Estimation errors are investigated as a function of sampling rate, signal-to-noise ratio, displacement and strain magnitudes, and frequency-dependent tissue attenuation. Results are from simulations using the FIELD II program to generate ultrasonic echo signals and tissue-mimicking phantom experiments using a Voluson 730 medical ultrasound scanner (GE medical systems Kretztechnik, Austria) that is equipped with a digital research interface that enables the export of beam-formed radio frequency echo data.

A High-Frame Rate High-Frequency Ultrasonic System for Cardiac Imaging in Mice

We report the development of a high-frequency (30-50 MHz), real-time ultrasonic imaging system for cardiac imaging in mice. This system is capable of producing images at 130 frames per second (fps) with a spatial resolution of less than 50 microm. A novel mechanical sector probe was developed that utilizes a magnetic drive mechanism and custom-built servo controller for high speed and accuracy. Additionally, a very light-weight (< 0.28 g), single-element transducer was constructed and used to reduce the mass load on the motor. The imaging electronics were triggered according to the angular position of the transducer in order to compensate for the varying speed of the sector motor. This strategy ensured the production of equally spaced scan lines with minimal jitter. Wire phantom testing showed that the system axial and lateral resolutions were 48 microm and 72 microm, respectively. In vivo experiments showed that high-frequency ultrasonic imaging at 130 fps is capable of showing a detailed depiction of a beating mouse heart.

Properties of an entropy-based signal receiver with an application to ultrasonic molecular imaging

Qualitative and quantitative properties of the finite part, H(f), of the Shannon entropy of a continuous waveform f(t) in the continuum limit are derived in order to illuminate its use for waveform characterization. Simple upper and lower bounds on H(f), based on features of f(t), are defined. Quantitative criteria for a priori estimation of the average-case variation of H(f) and log E(f), where E(f) is the signal energy of f(t) are also derived. These provide relative sensitivity estimates that could be used to prospectively choose optimal imaging strategies in real-time ultrasonic imaging machines, where system bandwidth is often pushed to its limits. To demonstrate the utility of these sensitivity relations for this application, a study designed to assess the feasibility of identification of angiogenic neovasculature targeted with perfluorocarbon nanoparticles that specifically bind to alpha(v)beta3-integrin expression in tumors was performed. The outcome of this study agrees with the prospective sensitivity estimates that were used for the two receivers. Moreover, these data demonstrate the ability of entropy-based signal receivers when used in conjunction with targeted nanoparticles to elucidate the presence of alpha(v)beta3 integrins in primordial neovasculature, particularly in acoustically unfavorable environments.

Real-time ultrasonic imaging of several order harmonics using double-layered piezoelectric transducer

A novel real-time ultrasonic imaging system for extracting several orders of harmonic ultrasonic pulse waves has been constructed using a double-layered piezoelectric transducer (DLPT). Enhanced odd and even harmonics can be detected in real-time by switching the DLPT to receive the ultrasonic pulse waves. To demonstrate the performance of the system, a steel ball target has been imaged as an application of the new system.

In vitro chronic hepatic disease characterization with a multiparametric ultrasonic approach

Although, high resolution, real-time ultrasonic (US) imaging is routinely available, image interpretation is based on grey-level and texture and quantitative evaluation is limited. Other potentially useful diagnostic information from US echoes may include modifications in tissue acoustic parameters (speed, attenuation and backscattering) resulting from disease development. Changes in acoustical parameters can be detected using time-of-flight and spectral analysis techniques. The objective of this study is to explore the potential of three parameters together (attenuation coefficient, US speed and integrated backscatter coefficient—IBC) to discriminate healthy and fibrosis subgroups in liver tissue. Echoes from 21 fresh in vitro samples of human liver and from a plane reflector were obtained using a 20-MHz central frequency transducer (6–30 MHz bandpass). The scan plane was parallel to the reflector placed beneath the liver. A 30 × 20 matrix of A-scans was obtained, with a 200-μm step. The samples were classified according to the Metavir scale in five different degrees of fibrosis. US speed, attenuation and IBC were estimated from standard methods described in the literature. Statistical tests were applied to the results of each parameter individually and indicated that it was not possible to identify all the fibrosis groups. Then a discriminant analysis was performed for the three parameters together resulting in a reasonable separation of fibrotic groups. Although the number of tissue samples is limited, this study opens the possibility of enhancing the discriminant capability of ultrasonic parameters of liver tissue disease when they are combined together.

Extracorporeal high-intensity focused ultrasound treatment for breast cancer

OBJECTIVE To evaluate the clinical safety and efficacy of using high-intensity focused ultrasound (HIFU) therapy, for breast cancer, and to select the appropriate methods in evaluating the therapeutic effects. METHODS A total of 24 patients with breast cancer underwent HIFU treatment 1-2 weeks before receiving modified radical mastectomy. During and after HIFU therapy, changes in blood pressure, breath, pulse and peripheral blood oxygen saturation were monitored. At the same time, the damage of the skin and tissue produced by HIFU at the target region was evaluated as well. Surgically excised samples were used for pathological examinations to evaluate the HIFU-induced destruction of the targeted tissue. Three patients received ~Tc-ECT and 1 MRI examinations before and after HIFU. RESULTS HIFU treatment had no apparent influence on either the tissue nearby the target or on vital signs of the patients. Pathological, ~"Tc-ECT and MRI examinations demonstrated that targeted tissue showed complete coagulative necrosis. CONCLUSION Under the guidance of real-time ultrasonic imaging, HIFU can effectively and safely destroy the breast cancer mass and 9emTc-ECT and MRI examination can be utilized to evaluate the therapeutic effects. H IFU may become one of the options for breast cancer therapy in the future.

Apparatus and system for real-time synthetic focus ultrasonic imaging

An apparatus for use in an ultrasonic imaging system adapted for generating synthetic focus images in real-time. The apparatus employs an integrated circuit architecture which is scalable and can be employed to construct real-time synthetic focus ultrasonic imaging systems having a large number of transducer array elements. The apparatus utilizes one field programmable gate array per image channel for data storage and sub-image generation. Each field programmable gate array includes on-chip block memories to store digitized ultrasonic signal return echo data and at least one block memory used to store data associated with each ultrasonic transmitter-receiver array pair. Logic inside the field programmable gate array calculates memory addresses during image generation to generate a time-of-flight surface and to form sub-images.