Three-dimensional Ultrasonic Imaging Research Articles

A 2D Ultrasonic Phased Array Optimization Framework Enabled by Reconfigurable Laser Induced Phased Arrays

Abstract Three-dimensional (3D) ultrasonic imaging enables the viewing of internal features in a more accurate way than cross-sectional imaging. 3D imaging requires two-dimensional (2D) ultrasonic phased arrays to resolve all three spatial dimensions through beamforming along azimuthal and elevation angles. 2D phased arrays pose a manufacturing and control challenge due to the requirement of large number of elements to satisfy the Nyquist sampling limit. This problem can be alleviated through the use of sparse ultrasonic array designs. The optimization process is critical, as this dictates the efficiency of suppression of grating lobes. The aim of this work is to establish a framework for design of optimized sparse 2D phased arrays. This is enabled by exploiting the reconfigurability of Laser Induced Phased Arrays (LIPAs). LIPAs are synthetic arrays produced by scanning one laser for ultrasound generation and another for ultrasound detection, independently of each other. The reconfigurability and decoupled ultrasonic generation and detection of this systems enables easy and fast implementation of any arbitrary array layout. The framework consists of an analytical model for parametric evaluation of designs. The model performs a parametric sweep on the generation and detection element positions for each array design in order to identify the optimal parameters, based on mean and maximum side-lobe level. In the presented framework, four array designs are utilized for the optimization process: matrix, random, Vernier and a novel array design the Rotated Array (RA).

High-resolution 3D ultrasonic imaging using high-frequency piezoelectric transmitter and ultra-multiple laser 2D scanning

In this paper, we extend a piezoelectric and laser ultrasonic system (PLUS) to a high-frequency version for high-sensitivity three-dimensional (3D) ultrasonic imaging by utilizing a unique characteristic of PLUS. PLUS combines a piezoelectric transmitter and a two-dimensional (2D) scan of a laser Doppler vibrometer (LDV). A high frequency can be used simply by adopting a high-frequency piezoelectric transmitter with a center frequency, such as 15 MHz, since the LDV has a broad bandwidth reception of 0–25 MHz. Furthermore, a 2D array receiver with a small interelement pitch can be achieved by precisely scanning a small laser irradiation spot. We experimentally demonstrate its 3D imaging capability for flat-bottom-hole and fatigue-crack specimens.

IMU-Assisted Manual 3D-Ultrasound Imaging Using Motion-Constrained Swept-Fan Scans.

Three-dimensional (3D) ultrasonic imaging can enable post-facto plane of interest selection. It can be performed with devices such as wobbler probes, matrix probes, and sensor-based probes. Ultrasound systems that support 3D-imaging are expensive with added hardware complexity compared to 2D-imaging systems. An inertial measurement unit (IMU) can potentially be used for 3D-imaging by using it to track the motion of a one-dimensional array probe and constraining its motion in one degree of freedom (1-DoF) rotation (swept-fan). This work demonstrates the feasibility of an affordable IMU-assisted manual 3D-ultrasound scanner (IAM3US). A consumer-grade IMU-assisted 3D scanner prototype is designed with two support structures for swept-fan. After proper IMU calibration, an appropriate KF-based algorithm estimates the probe orientation during the swept-fan. An improved scanline-based reconstruction method is used for volume reconstruction. The evaluation of the IAM3US system is done by imaging a tennis ball filled with water and the head region of a fetal phantom. From fetal phantom reconstructed volumes, suitable 2D planes are extracted for biparietal diameter (BPD) manual measurements. Later, in-vivo data is collected. The novel contributions of this paper are (1) the application of a recently proposed algorithm for orientation estimation of swept-fan for 3D imaging, chosen based on the noise characteristics of selected consumer grade IMU (2) assessment of the quality of the 1-DoF swept-fan scan with a deflection detector along with monitoring of maximum angular rate during the scan and (3) two probe holder designs to aid the operator in performing the 1-DoF rotational motion and (4) end-to-end 3D-imaging system-integration. Phantom studies and preliminary in-vivo obstetric scans performed on two patients illustrate the usability of the system for diagnosis purposes.

Multi-Element Synthetic Aperture Focusing Three-Dimensional Ultrasonic Imaging

In the field of industrial non-destructive testing, the three-dimensional imaging technology of ultrasonic testing can intuitively represent the three-dimensional spatial characteristics of defects, making it convenient for non-destructive testing personnel to make accurate judgments on the internal defect information of the tested workpiece. This article conducts a comprehensive study on multi element synthetic aperture focused ultrasound imaging. Based on the radiation theory of sound field, the sound pressure distribution of multi element aperture was derived, and the sound field and defect response of single element, multi element focused, and multi element unfocused were simulated. It was found that multi element unfocused sound field is more suitable for synthetic aperture focused ultrasound imaging. The results indicate that in far-field conditions, multi element synthetic aperture focused ultrasound imaging can achieve higher imaging quality and resolution than single element synthetic aperture focused imaging.

Experimental Study of Aperiodic Plane Wave Imaging for Ultrafast 3-D Ultrasound Imaging.

Although plane wave imaging (PWI) with multiple plane waves (PWs) steered at different angles enables ultrafast three-dimensional (3-D) ultrasonic imaging, there is still a challenging tradeoff between image quality and frame rate. To address this challenge, we recently proposed the aperiodic PWI (APWI) with mathematical analysis and simulation study. In this paper, we demonstrate the feasibility of APWI and evaluate the performance with phantom and in vivo experiments. APWI with a concentric ring angle pattern (APWI-C) and APWI with a sunflower pattern (APWI-S) are evaluated. For experimental verification of the methods, the experimental results are compared with simulation results in terms of the spatial resolution and the mainlobe-to-sidelobe ratio. In addition, the performance of APWI is compared with that of conventional PWI by using a commercial phantom. To examine the potential for clinical use of APWI, a gallstone phantom study and an in vivo carotid artery experiment are also conducted. In the phantom study, the APWI methods provide a contrast ratio approximately 2-3 dB higher than that of PWI. In a gallstone experiment, the proposed methods yield 3-D rendered stone images more similar to the real stones than PWI. In the in vivo carotid artery images, APWI reduces the clutter artifacts inside the artery. Phantom and in vivo studies show that the APWI enhances the contrast without compromising the spatial resolution and frame rate. This study experimentally demonstrates the feasibility and advantage of APWI for ultrafast 3-D ultrasonic imaging.

Three-Dimensional Ultrasonic Imaging and Acoustic Emission Monitoring of Hydraulic Fractures in Tight Sandstone

Hydraulic fracturing is an important means for the development of tight oil and gas reservoirs. Laboratory rock mechanics experiments can be used to better understand the mechanism of hydraulic fracture. Therefore, in this study we carried out hydraulic fracturing experiments on Triassic Yanchang Formation tight sandstone from the Ordos Basin, China. Sparse tomography was used to obtain ultrasonic velocity images of the sample during hydraulic fracturing. Then, combining the changes in rock mechanics parameters, acoustic emission activities, and their spatial position, we analyzed the hydraulic fracturing process of tight sandstone under high differential stress in detail. The experimental results illuminate the fracture evolution processes of hydraulic fracturing. The competition between stress-induced dilatancy and fluid flow was observed during water injection. Moreover, the results prove that the “seismic pump” mode occurs in the dry region, while the “dilation hardening” and “seismic pump” modes occur simultaneously in the partially saturated region; that is to say, the hydraulic conditions dominate the failure mode of the rock.

Detection Technology and Application of Three-Dimensional Ultrasonic Imaging of Concrete

Concrete is a very important structural material in engineering buildings and it is of great significance and practical value to visually describe the internal components and defects of concrete structures by means of imaging. In this paper, a three dimensional imaging detection technology for concrete has been introduced, which employs special techniques such as point contact, dry coupling, array and shear wave observation, and the result of the test block experiment and engineering practice shows that this method can accurately detect abnormal parts of steel bar and void in steel fiber reinforced concrete.

Frequency-domain imaging algorithm for ultrasonic testing by application of matrix phased arrays

Constantly increasing demand for high-performance materials and systems in aerospace industry requires advanced methods of nondestructive testing. One of the most promising methods is ultrasonic imaging by using matrix phased arrays. This technique allows to create three-dimensional ultrasonic imaging with high lateral resolution. Further progress in matrix phased array ultrasonic testing is determined by the development of fast imaging algorithms. In this article imaging algorithm based on frequency domain calculations is proposed. This approach is computationally efficient in comparison with time domain algorithms. Performance of the proposed algorithm was tested via computer simulations for planar specimen with flat bottom holes.

Medical Image Condensation Based on Wavelet Transform

This paper based on the peculiarity of wavelet transform that its transform only in vacuum region and frequency region, decompose image use the theory of wavelet, obtain a series sub-image of different resolution ratio. The value of higeresolution ratio sub-image is all verge on 0, the phenomenon is more obviously in high frequency, so that, the mainly proportion is low frequency to a image. Use wavelet decomposition get rid of the high frequency, only reservation low frequency, to realize the aim of condensation image. Through the simulation of contradistinctive image of cerebra framework remotion between three-dimensional ultrasonic imaging in course of OPS and MIR preceding OPS validated the feasibility by Matlab.

Apparatus For Two-Dimensional Transducers Used In Three-Dimensional Ultrasonic Imaging

A single chip transducer apparatus that includes on-chip electronic circuitry which, when connected properly to a two-dimensional matrix of ultrasonic transducer elements, provides enough information to an external imaging system to form three-dimensional images of the subject of interest. In a preferred embodiment, the circuitry provides an amplifier for each transducer element, and then conditions the output of the amplifier in several ways. In one embodiment of the invention, the elements' analog voltages are stored in a sample and hold circuit, and time multiplexed into a high speed line driver that sends many elements data down the interconnect to the system's high speed Analog to Digital converters. In another embodiment, the gain of the amplifiers can be controlled in time to provide aperture translation and time based expansion for translating and focusing image slices in the elevation direction.

Three-dimensional ultrasonic Nakagami imaging for tissue characterization

The two-dimensional (2D) Nakagami image complements the ultrasound B-scan image when attempting to visualize the scatterer properties of tissues. The resolution of the Nakagami image is lower than that of the B-scan image, since the former is produced by processing the raw envelope data using a 2D sliding window with side lengths typically corresponding to three times the pulse length of the incident ultrasound. This paper proposes using three-dimensional (3D) Nakagami imaging for improving the resolution of the obtained Nakagami image and providing more complete information of scatterers for a better tissue characterization. The 3D Nakagami image is based on a voxel array composed of the Nakagami parameters constructed using a 3D sliding cube to process the 3D backscattered raw data. Experiments on phantoms with different scatterer concentrations were carried out to determine the optimal size of the sliding cube for a stable estimation of the Nakagami parameter. Tissue measurements on rat livers without and with fibrosis formation were further used to explore the practical feasibility of 3D Nakagami imaging. The results indicated that the side length of the cube used to construct the 3D Nakagami image must be at least two times the pulse length, which improved the resolution for each Nakagami image frame in the 3D Nakagami image. The results further demonstrated that the 3D Nakagami image is better than the conventional 2D Nakagami image for complementing the B-scan in detecting spatial variations in the scatterer concentration and classifying normal and fibrotic livers. This study suggests that 3D Nakagami imaging has the potential to become a new 3D quantitative imaging approach.

Value of three-dimensional ultrasonic imaging of vascular volume in assessing acute rejection of transplanted kidneys

Objective To evaluate the value of three-dimensional (3D) ultrasonic imaging of vascular volume in assessing postoperative acute rejection(AR) of renal transplant patients. Methods Color Doppler flow imaging(CDFI) and 3D vascular volumetric parameters were collected and analyzed in 30 cases with stable renal function (control group) and 13 cases with AR of kidney transplantation (AR group). The diagnostic performances of each ultrasonic parameter were compared by receiver operating characteristic (ROC) curve. Results The parameters of resistance index(RI) and pulsatility index(PI) in AR group were significantly higher than those in control group( P 0. 05) was found compared the area under VFI curve to those areas under VI,FI and MG curves;Comparing the area under VFI curve to those under RI, V and PI,there were significant differences( P <0. 05). Taking VFI≤18. 78% as the critical value, the sensitivity and specificity for the diagnosis of AR of transplanted kidneys were 70. 0% and 93. 3% ,and the positive and negative predictive values were 60. 8% and 93. 4%, respectively. Conclusions The sensitivity and specifity of 3D vascular volumetric imaging parameter VFI in the diagnosis of transplanted kidneys with AR were higher than those of blood flow parameters RI and PL VFI with the optimal critical value of ≤18. 78% might be a useful index for the early diagnosis of transplanted kidneys with AR. Key words: Ultrasonography; Kidney transplantation; Graft rejection; Three-dimensional vascular volume imaging

Three-dimensional ultrasound imaging

This review is about the development of three-dimensional (3D) ultrasonic medical imaging, how it works, and where its future lies. It assumes knowledge of two-dimensional (2D) ultrasound, which is covered elsewhere in this issue. The three main ways in which 3D ultrasound may be acquired are described: the mechanically swept 3D probe, the 2D transducer array that can acquire intrinsically 3D data, and the freehand 3D ultrasound. This provides an appreciation of the constraints implicit in each of these approaches together with their strengths and weaknesses. Then some of the techniques that are used for processing the 3D data and the way this can lead to information of clinical value are discussed. A table is provided to show the range of clinical applications reported in the literature. Finally, the discussion relating to the technology and its clinical applications to explain why 3D ultrasound has been relatively slow to be adopted in routine clinics is drawn together and the issues that will govern its development in the future explored.

Three-dimensional ultrasonic imaging operation using FPGA

The feasibility of three-dimensional (3D) ultrasound imaging methods that involve computations depends on the performance of a computing system, which requires high-speed image reconstruction. Therefore, we examine the hardware (HW) implementation of the algorithm utilizing a field-programmable-gate-array (FPGA). Subsequently, we analyze the critical path delay of the HW and reduce the delay by modifying the architecture using FPGA resources to increase the maximum frequency.This paper presents a HW implementation approach for performing 3D ultrasound imaging.

Three-dimensional ultrasound biomicroscopy, environmental and conventional scanning electron microscopy investigations of the human zonula ciliaris for numerical modelling of accommodation

Biomechanical modelling of the accommodation process is a useful tool for studying the mechanism of accommodation and presbyopia and can aid in the development of accommodative lens-replacing materials. Existing biomechanical models, however, use a very simplified zonula structure. The aim of this study was to use three-dimensional ultrasonic imaging and scanning electron microscopy to provide a more detailed, three-dimensional description of the structure of the human zonula to improve the modelling of accommodation. Five human eyes were examined without invasive manipulation using a custom-made three-dimensional ultrasonic imaging technique that allows scanning of features with a spatial resolution of 30 microm. Environmental and conventional scanning electron microscopy (SEM) provided information to complement the ultrasonic images for use in development of a more anatomically correct finite-element model of the zonula structures. These data along with the material properties of the ocular tissue structures were used to construct an advanced geometric model for finite-element simulation of the accommodation process. Images were obtained through three-dimensional ultrabiomicroscopy (3D-UBM) of anatomical features heretofore not directly imagable in their native state. Ciliary processes and zonula structures were clearly separated by both the 3D-UBM and the SEM methods. It was found that fibres inserting on the anterior and posterior lens capsule emerge anteriorly at the ciliary body. Fibres emerging near the pars plana insert on the lens and the ciliary body. No X-shaped crossing fibres were found. Modelling of the accommodation process with both the simple and the more complex geometric models produced refractive power changes comparable with in vivo findings. The 3D-UBM allowed examination of zonula structures in their native state with minimized preparation artefacts. While these data were incorporated into a complex and more anatomically correct finite-element simulation of intraocular features including lens, zonular system and ciliary body it was found that a simplified zonular model is sufficient for the numerical simulation of the accommodation process.

Building three-dimensional images using a time-reversal chaotic cavity

The design of two-dimensional (2-D) arrays for three-dimensional (3-D) ultrasonic imaging is a major challenge in medical and nondestructive applications. Thousands of transducers are typically needed for focusing and steering in a 3-D volume. In this article, we propose a different concept allowing us to obtain electronic 3-D focusing with a small number of transducers. The basic idea is to couple a small number of transducers to a chaotic reverberating cavity with one face in contact with the body of the patient. The reverberations of the ultrasonic waves inside the cavity create at each reflection virtual transducers. The cavity acts as an ultrasonic kaleidoscope multiplying the small number of transducers and creating a much larger virtual transducer array. By exploiting time-reversal processing, it is possible to use collectively all the virtual transducers to focus a pulse everywhere in a 3-D volume. The reception process is based on a nonlinear pulse-inversion technique in order to ensure a good contrast. The feasibility of this concept for the building of 3-D images was demonstrated using a prototype relying only on 31 emission transducers and a single reception transducer.

Real-time Three-dimensional Ultrasonic Images Equipment(&lt;Special Issue&gt; Surgical Assistance Environment)

単純レントゲン画像にX線CT, 核磁気共鳴イメージング(MRI)および超音波診断装置の断層画像を加え, 病状を診断する画像診断は今, 全盛期を迎えている. これは画像の分解能向上や表示時間の短縮, また3次元画像表示や多種の機能画像表示の実現に起因する. 医師らはこれにより早期に患部の詳細な情報を正確に取得することができ, 診断のみならずに治療方針の重要な情報を得ることが可能になった. 医師は病気を単に治療する段階から, より患者に優しい治療法へと医療の質的向上を図ることが可能となって来た. さらにはそれら診断画像が実時間で表示できるようになり, 診断画像を治療中に治療の支援手段として使用できるようになって来た. 超音波診断装置では手術中に超音波画像を用いる術中超音波法が開発され, 現在では肝臓手術を中心に多くの部位で応用されている. 本稿では術中超音波法が示すように超音波のもつ, 実時間表示が可能で被曝のない安全でかつ小型である特徴が手術支援装置として優れていること, 特に超音波3次元画像が直感として理解しやすい画像であり, 治療支援としての応用が期待される点を, 研究例を紹介しながら述べ, 今後の動向を予想する.

Time reversal kaleidoscope: A smart transducer for three-dimensional ultrasonic imaging

The design of two dimensional (2D) arrays for three dimensional (3D) ultrasonic imaging is a major challenge in medical and nondestructive applications. Thousands of transducers are typically needed for beam focusing and steering in 3D volumes. Here, we report a promising approach for producing 3D images with a small number of transducers using the combined concepts of time reversal mirrors and chaotic reverberating cavities. Due to multiple reverberations inside the cavity, a “kaleidoscopic” transducer array is created with thousands of virtual transducers equivalent to 2D matrices. Beyond the scope of 3D medical imaging, this work leads to the concept of “smart” transducer.

Study of a breast tumor extraction algorithm for three-dimensional ultrasound images, using multiple space differentiation filters: Automated breast tumor extraction algorithm with improved accuracy

The system to be developed in the present study will enable us to extract the tumor region automatically from three-dimensional ultrasonic images of the breast, and differentiate benign from malignant tumors by using the characteristics of their surface form. In application of such a system, the accuracy of diagnosis greatly depends on its ability to extract tumor automatically. We developed an algorithm for determination of the tumor region using fuzzy reasoning, that is, we classified each voxel of three-dimensional images as “tumor,” “normal tissue” and “boundary,” and, using relaxation techniques to resolve regional contradictions, made final decisions as to the tumor region. It must be noted that, according to this algorithm, a three-dimensional the space differentiation filtering automatically generates a membership function for the fuzzy reasoning. Previous attempts of extracting tumor used a single LoG filter as the space differentiation filter. We recently developed a method which can cope with diverse ultrasound images more flexibly. With this new method, multiple DoG filters with varying characteristics are prepared in addition to the LoG filter, and the optimum one is selected from multiple extraction results. The introduction of this method improved the accuracy of extraction.

Study of the automated breast tumor extraction using 3D ultrasound imaging: The usefulness of depth-width ratio and surface-volume index

We applied quantitative parameters in three-dimensional ultrasonic images to distinguish benign from malignant breast tumors in 29 benign cases including 8 cysts and 21 fibroadenomas, and 32 malignant cases including 23 ductal carcinomas, 2 special types of carcinoma, 1 malignant lymphoma and 6 others. This procedure involved simultaneously acquiring video data from real-time ultrasonic images and recording the original position and orientation of the probe. Both sets of data were fed directly into a desktop computer. Fuzzy reasoning and relaxation techniques were use to automatedly extract the shape of the tumor and render it in three dimensions. We then evaluated three parameters: 2D-D/W, the so-called depth-width ratio measured in B-mode images: 3D-D/W; and the S/V index ([surface area](3)/36π [volume](2)) calculated from the three-dimensional volume extracted with this system. All three parameters were significantly higher in the malignant group (averages: 0.81, 0.64, and 11.3, respectively) than in the benign group (averages: 0.62, 0.47, and 3.78, respectively). All three parameters were thus found to be useful in differentiating the two groups.