Probe Array Research Articles

Risk-based ultrasound probe quality assurance - a single center proof-of-concept study.

Ultrasound probe quality assurance is an underserved and underregulated area in medical imaging. While several testing methods exist, their availability and adoption remains varied, and the frequency of testing is often insufficient. Here we aimed to conduct a user-driven simple and rapid probe quality testing approach and to evaluate its rationale.Testing was based on physical examination of probe integrity (all probes) and in-air reverberation check (for curvilinear and linear array probes), findings, as well as probe age were registered. Prior to assessment, probes were divided into a high-risk vs. a low-risk category, based on the perceived risk of probe damage as a result of the typical application (e.g., non-invasive vs. interventional, inpatient vs. point-of-care).17.4% of the low-risk and 31.4% of high-risk probes demonstrated physical wear or damage. Reverberation artifacts were significantly more frequent (68%) in the high-risk category vs. the low-risk one (29.4%). Probes with either physical or reverberation faults were significantly older on average.The simple, rapid investigational technique uncovered an alarming percentage of probe damage or faults. It also identified immediately solvable technical issues (e.g., poor cable contact mimicking dropout). High-risk probe usage resulted in an increased rate of reverberation errors and physical damage. Risk-based, frequent rapid observational testing of ultrasound probes could substantially improve both diagnostic quality and patient safety.

Feasibility of Backscattering Coefficient Evaluation of Soft Tissue Using High-Frequency Annular Array Probe

The objective of this work is to address the need for versatile and effective tissue characterization in abdominal ultrasound diagnosis using a simpler system. We evaluated the backscattering coefficient (BSC) of several tissue-mimicking phantoms utilizing three different ultrasonic probes: a single-element transducer, a linear array probe for clinical use, and a laboratory-made annular array probe. The single-element transducer, commonly used in developing fundamental BSC evaluation methods, served as a benchmark. The linear array probe provided a clinical comparison, while the annular array probe was tested for its potential in high-frequency and high-resolution ultrasonic observations. Our findings demonstrate that the annular array probe meets clinical demands by providing accurate BSC measurements, showcasing its capability for high-frequency and high-resolution imaging with a simpler, more versatile system.

Highly Sensitive Phased Array Probes based on Capacitive Micromachined Ultrasonic Transducers

Capacitive Micromachined Ultrasonic Transducers (CMUTs) offer a wide freedom of design for ultrasonic phased arrays. They are characterized, in comparison to piezoelectric transducers, by a higher sensitivity in receiving and a wider bandwidth based on their physical properties. Especially in combination with integrated preamplifiers the high receiving sensitivity compensates or rather overcompensates the lower transmission power of the CMUT in single probe applications with pulse-echo technique. This asymmetric behavior opens new opportunities in the application. In medical diagnostics it allows to meet the maximum permissible ultrasonic radiation force with the best sensitivity. In nondestructive testing the transmission power can be increased by the combination of a piezoelectric probe for transmitting and a CMUT probe for receiving. Especially in double probe techniques, such as pitch-catch or time-of-flight diffraction (TOFD), this is an efficient extension of the conventional approach with two piezoelectric transducers. The CMUT array probes developed by Fraunhofer IPMS with integrated preamplifier and bias voltage converter powered by a standard USB-A connector can be applied as one to one substitute for piezoelectric phased arrays with commercially available ultrasonic devices without adaption or additional electronics. The CMUT arrays are best suited for immersion technique and medical sonography because of their natural matching to water-like materials. They are applicable as well for solid surfaces with a special coating. We present the first results of ultrasonic imaging with our CMUT array probes in comparison with a commercially available piezoelectric phased array probe.

Automated self-adjustment of array probe with a robotic ultrasonic test system

Ultrasonic testing of objects with complex geometries often requires the use of a robotic arm to position the probe perpendicular to the local surface. Using immersion makes it possible to test these objects with standard ultrasonic linear array probes. Here, the probe positions and orientations provided by the robot are used for merging the locally acquired image data into a 3D-reconstruction. The quality of this reconstruction is highly dependent on the alignment of the position of the physical probe with the position used in the digital model. For common industrial tools, the tool center point (TCP) is usually acquired using geometric features of the tools. However, for ultrasonic arrays in immersion, there is a water standoff between the probe and the test object, therefore the TCP is in free space in front of the array and cannot be acquired with the common method. To overcome this challenge, we propose a method that allows the robotic ultrasonic system to automatically self-adjust the position and orientation of the ultrasonic probe using a test block made of steel with defined geometric features as a target for referencing. For each of the six degrees of freedom, a scan and adjustment routine are established using the data based on the actual ultrasound characteristics of the probe. Given a coarse pre-definition of the tool position and the known target test block, minimal human interaction is required to supervise the adjustment method, leading to higher quality reconstructions than with manual adjustment.

An Experimental Study of Wave Impact Loads on an FPSO Bow in 2D Wave-Tank

<i>In harsh environments, an floating production storage and offloading (FPSO) is occasionally damaged by impact loads, such as bow flare slamming and green water. This study conducted an impact load measurement experiment on a model of an FPSO bow in a 2D wave tank. Three types of frequency-focused waves (steep, spilling, and plunging) were generated, and the speed and slope of the waves were measured. Seven wave probes were placed in a row, and the wave elevation was measured to determine the speed and slope of the waves. In addition, the side of the 2D wave tank was photographed with a high-speed camera. The speed and slope of the waves obtained from the wave probe array agreed well with those obtained from the photographs taken using a high-speed camera. In the case of a steep wave, wave runup occurred at the bow before the wave reached the bow of the FPSO, so no impact load was generated, and only hydrostatic pressure was measured. Impact loads were generated in the spilling and plunging waves, and the magnitude of impact loads using the Von Karman’s estimation formula and the impact loads measured in model tests showed similar values.</i>

Ultrasonographic approach to visualize the medial shoulder compartment and diagnose medial glenohumeral ligament and subscapularis lesions in dogs.

To provide a video tutorial on the diagnostic ultrasound approach to the medial compartment of the canine shoulder and provide comparisons of normal and pathological images with corresponding MRI. Dogs undergoing diagnostic ultrasound of the medial shoulder. The medial shoulder was positioned in flexion with external rotation to allow transducer access, clipped, and scrubbed with dilute chlorhexidine. A 2- to 14-MHz linear array probe with a footprint of 50 mm (V8 ultrasound system; Samsung) was used to visualize the medial glenohumeral ligament (MGL), subscapularis, and coracobrachialis with coupling gel, confirmed by cadaveric ultrasound-guided dye injection and dissection. Ultrasound and corresponding MRI were then used to contrast normal anatomy to a live sedated dog with clinical subscapularis tendinopathy and MGL desmopathy. Proton density-weighted MRI sequences (1.5T Vantage Orian; Canon) using a flex coil were able to identify all 3 structures and corresponded to ultrasound findings for normal and pathological anatomy. Diagnostic ultrasound identified normal and abnormal structures of the medial shoulder (coracobrachialis, subscapularis, and MGL). All imaging correlated well to MRI. Medial compartment disease of the shoulder is a well-described cause of canine lameness, but diagnosis has traditionally relied on MRI or arthroscopy. Prior ultrasound approaches did not distinguish MGL components, failed to consistently identify normal or surgically transected ligaments, and have not been studied in vivo. Our approach is different and can play an important role in diagnosing medial compartment lesions, as it possesses greater anatomical visualization than arthroscopy and is noninvasive, accomplished with sedation, and relatively accessible and affordable.

Two-dimensional magnetic field diagnostics of plasma based on nano-thin-film probe

In this paper, we propose a method to determine the diagnostics of magnetic fields based on arrays of nano-thin-film probes that are manufactured by using magnetron sputtering-based fabrication and arranged in a two-dimensional (2D) topological design. Measurements of the magnetic field and its wave number based on the proposed method were validated in a linear cylindrical plasma device, the linear experimental advanced device. We manufactured nano-thin-film probes, each with a thickness of 500 nm, a diameter of 9 mm, and a shape similar to the Greek letter “omega” by depositing silver nanoparticles generated through magnetron sputtering to improve the accuracy of the fabrication as well as their time response. The 2D topological arrangement of the array of probes enabled the determination of the diagnostics of the magnetic field and its wave number at a high spatial resolution. Measurements of the amplitude of the magnetic field and its wavenumber obtained using the proposed method were in good agreement with the results of theoretical simulations in COMSOL, which verifies its high reliability and accuracy in obtaining low-pressure plasma diagnostics. In future work, we plan to apply our diagnostic method based on the array of thin-film probes to scenarios that require a high spatial resolution.

Synthesis of group-IV ternary and binary semiconductors using epitaxy of GeH3Cl and SnH4

Ge1−x−ySixSny alloys were grown on Ge buffers via reactions of SnH4 and GeH3Cl. The latter is a new CVD source designed for epitaxial development of group-IV semiconductors under low thermal budgets and CMOS-compatible conditions. The Ge1−x−ySixSny films were produced at very low temperatures between 160 and 200 °C with 3%–5% Si and ∼5%–11% Sn. The films were characterized using an array of structural probes that include Rutherford backscattering, x-ray photoelectron spectroscopy, high-resolution x-ray diffraction, scanning transmission electron microscopy, and atomic force microscopy. These studies indicate that the films are strained to Ge and exhibit defect-free microstructures, flat surfaces, homogeneous compositions, and sharp interfaces. Raman was used to determine the compositional dependence of the vibrational modes indicating atomic distributions indistinguishable from those obtained when using high-order Ge hydrides. For a better understanding of the growth mechanisms, a parallel study was conducted to investigate the GeH3Cl applicability for synthesis of binary Ge1−ySny films. These grew strained to Ge, but with reduced Sn compositions and lower thicknesses relative to Ge1−x−ySixSny. Bypassing the Ge buffers led to Ge1−ySny-on-Si films with compositions and thicknesses comparable to Ge1−ySny-on-Ge; but their strains were mostly relaxed. Efforts to increase the concentration and thickness of Ge1−ySny-on-Si resulted in multiphase materials containing large amounts of interstitial Sn. These outcomes suggest that the incorporation of even small Si amounts in Ge1−x−ySixSny might compensate for the large Ge–Sn mismatch by lowering bond strains. Such an effect reduces strain energy, enhances stability, promotes higher Sn incorporation, and increases critical thickness.

Metallic material microstructure grain size measurements from backscattering signals in ultrasonic array data sets

Ultrasound backscattering signals from material microstructures can be used to evaluate the material microstructure grain size. This typically involves making pulse-echo immersion measurements at multiple locations using a focused ultrasonic transducer in order to obtain an accurate estimate of the root-mean-square amplitude of the back-scattered signal at a specified focal position. However, this restricts some practical applications of using such techniques in, for example, on-line measurements in high-value manufacturing and in-service inspections where multiple immersion measurements are not feasible to use. The main benefit of using ultrasonic phased arrays is that one array probe at one position can focus ultrasound beams at multiple points using different focal laws either physically or in data postprocessing. Potentially this means that accurate grain size measurements can be obtained from a single array measurement. In this paper, the classic backscattering method for conventional transducers is adapted to be used for full matrix capture datasets from an ultrasonic array. Three-dimensional ultrasonic models are developed in the proposed inverse process to measure material microstructure grain size. Experimental validations were performed on two metallic materials: copper (EN1652) and bright mild steel (BS970). A good agreement is shown between the experimentally measured grain sizes from array data and metallography measurements. Compared to the classic pulse-echo immersion back-scattering measurements, the proposed method enables accurate measurement of grain size in a direct contact configuration at fewer locations. This has potential to make on-line grain size measurements possible.

Comparative Approach to Performance Estimation of Pulsed Wave Doppler Equipment Based on Kiviat Diagram

Quality assessment of ultrasound medical systems is a demanding task due to the high number of parameters to quantify their performance: in the present study, a Kiviat diagram-based integrated approach was proposed to effectively combine the contribution of some experimental parameters and quantify the overall performance of pulsed wave Doppler (PWD) systems for clinical applications. Four test parameters were defined and assessed through custom-written measurement methods based on image analysis, implemented in the MATLAB environment, and applied to spectral images of a flow phantom, i.e., average maximum velocity sensitivity (AMVS), velocity measurements accuracy (VeMeA), lowest detectable signal (LDS), and the velocity profile discrepancy index (VPDI). The parameters above were scaled in a standard range to represent the four vertices of a Kiviat plot, whose area was considered the overall quality index of the ultrasound system in PWD mode. Five brand-new ultrasound diagnostic systems, equipped with linear array probes, were tested in two different working conditions using a commercial flow phantom as a reference. The promising results confirm the robustness of AMVS, VeMeA, and LDS parameters while suggesting further investigations on the VPDI.

Ocular Ultrasound, a neglected tool in the diagnosis of central retinal artery occlusion.

Purpose: To discuss the practical utility of ocular ultrasound in central retinal artery occlusion (CRAO). Methods: Ocular ultrasound was obtained in 4 patients with CRAO using a 20 MHz Annular Array Probe of the ABSolu (Quantel Medical, Texas, USA) ultrasound machine. Results: The causative embolus occluding the central retinal artery was detected on ocular ultrasound imaging in four patients with CRAO. Conclusion: Ocular ultrasound, including newer generation, higher frequency ultrasound probes, aids in the detection of the “retrobulbar spot sign”, a finding that seems to be related to embolic central retinal artery occlusion. This sign will orient investigations towards finding an embolic source.

Examining the Utility of the Mammalian Methylation Array for Pan-Mammalian Analysis of Monozygotic Twinning.

Human identical twins are born at a rate of 3-4 per 1000 live births. Many other mammals also occasionally produce monozygotic twins, referred to as sporadic polyembryony. The underlying mechanisms are unknown. Through epigenome-wide association studies (EWAS), we identified a robust DNA methylation signature in somatic tissues from human monozygotic (MZ) twins, comprising 834 differentially methylated positions (MZ-DMPs). The results point to a connection between monozygotic twinning and early genome programming and enable new angles to study monozygotic twinning. The mammalian methylation array (MMA) measures 38,608 CpGs focusing on regions that are well-conserved across many mammalian species, allowing for pan-mammalian comparative epigenomic studies. Here, we successfully map human MZ-DMPs to probes of the mammalian methylation array across 157 mammalian genomes. As expected, based on the modest probe overlap between Illumina 450k/EPIC and mammalian methylation array probes, only a subset of MZ-DMPs reside in conserved regions covered by the mammalian methylation array. These include probes mapping to NPAS3, KLHL35, CASZ1, and ATP2B2. Re-analysis restricting the original EWAS in humans to conserved MMA regions yielded additional MZ-DMPs, suggesting that more loci may be detected by application of the mammalian array to monozygotic twins. In conclusion, the mammalian methylation array may prove to be a promising platform to study whether a shared DNA methylation signature of sporadic polyembryony exists across diverse mammalian species. This may potentially point to shared underlying mechanisms.

Ultrasound-guided arthrocentesis and intra-articular injection of the hip and shoulder joints in the dog.

To provide a video tutorial on ultrasound-guided arthrocentesis and injection of the canine hip and shoulder joints. Dogs undergoing arthrocentesis or intra-articular injection for diagnostic or therapeutic purposes. The target joint is visualized in long axis with a 70% isopropyl alcohol medium and linear array probe with a frequency range of 2 to 14 MHz and footprint of 50 mm after clipping a window and preparing the region sterilely. The needle is inserted, bevel up, in long axis with the probe angled at the appropriate trajectory to enter the joint space. The needle is advanced until the tip is visualized entering the joint. Aspiration to obtain synovial fluid can further confirm needle placement or provide diagnostic sampling prior to injection. The aspirate syringe is exchanged for that containing the therapeutic agent, and injectate can then be visualized entering and/or expanding the joint upon injection. Ultrasound-guided arthrocentesis will help identify deep appendicular joints (hip and shoulder), avoid surrounding vasculature, confirm needle placement, and target joint fluid pocketing. Needle guidance into a joint can reduce iatrogenic tissue damage from inappropriate needle placement and/or by minimizing attempts. For arthrocentesis, ultrasound guidance can maximize joint fluid volume acquisition for diagnostic purposes (cytology, culture, and fluid analysis) while also avoiding blood contamination. For joint injections, ultrasound will help ensure real-time intra-articular delivery of the injectate (regardless of attaining synovial fluid feedback) to maximize the therapeutic effect. For either purpose, iatrogenic tissue damage and procedure time are minimized.

Experimental study of oil-water two-phase flow patterns in a vertical large diameter pipe

The flow structure and the phase inversion have great influence on the flow measurement in vertical upward oil-water two-phase flow. This paper attempts to investigate the flow patterns in oil-water flows through a vertical upward large pipe with the designed mini-conductance array probes measurement system and the vertical multi-electrode array (VMEA) measurement system. According to the output waveform of the mini-conductance array probes, the oil-in-water flow, transition flow and water-in-oil flow can be identified effectively. The fluctuating signals of the VMEA is processed by the recurrence plot and the time-frequency representation, the results show that the VMEA conductance signal with average measurement characteristics can realize an effective identification of the above three flow patterns, which has a good agreement with the results of the mini-conductance array probes. Finally, via comparing with previous published flow pattern transition boundary models in different pipe diameters, it is founded that the boundary line of the transition to oil-in-water based on the kinematic wave-based model and the observation-based model in the same diameter pipe are consistent with our experimental data. And the pipe diameter affects the flow pattern transition, compared with the boundary in small diameter pipe, the phase inversion requires a larger oil velocity, and the transition zone becomes narrower in large diameter pipe.

Reduction of turbulence by enhanced low-frequency zonal flow-like structures in HL-2A edge plasmas

Abstract A low-frequency zonal flow-like (LFZF-like) structure peaking at f ≈ 2.0 kHz has been observed in HL-2A ohmically heated deuterium plasmas using a combined Langmuir probe array. This time-varying potential structure, which has axisymmetric characteristics (n = 0) and a finite radial correlation length (less than 1 cm), was identified to be generated by the three-wave interaction in small-scale turbulence. The results illustrate that the amplitude of the LFZF-like structure dramatically increases with the influence of impurity ions, which is mainly due to the increased strength in the nonlinear energy transfer by the turbulence vortex symmetry-breaking process. Consequently, the enhanced LFZF-like structure has the ability to stabilize the local turbulence via the shearing decorrelation mechanism as demonstrated in this experiment. The observed results given here reveal the essential role played by the LFZF-like structure in the reduction of turbulence levels, which could advance our understanding of the multi-scale physics governing turbulence and the resulting transport in magnetically confined plasmas.

Assessment of perineal body properties in women with stress urinary incontinence using Transperineal shear wave elastography

Limited data on the correlation between the perineal body (PB) and stress urinary incontinence (SUI) are available. The objectives of this study were to quantify the PB using shear wave elastography (SWE) technology with a high-frequency linear array probe to evaluate the relationship between the properties of PB and stress urinary incontinence (SUI). This study included 64 women with SUI and 70 female control participants. The length, height, perimeter, and area of PB in all participants were calculated using transperineal ultrasound, and the elasticity of PB was assessed by SWE at rest and during the maximal Valsalva maneuver, respectively. In addition, the comparison of PB parameters between the patients with SUI and the healthy participants was conducted. The transperineal ultrasound and SWE examination was performed in 134 participants, and the elastic modulus values were significantly increased from participants at rest to those during the maximal Valsalva maneuver in all participants (Emax: 35.59 versus 53.13 kPa, P < 0.001; and Emean: 26.97 versus 40.25 kPa, P < 0.001). Emax and Emean of PB exhibited significant differences during the maximal Valsalva maneuver between the SUI group and the control group (47.73 versus 58.06 kPa, P < 0.001; and 35.78 versus 44.33 kPa, P < 0.001) and had a negative correlation with SUI. The BMI and PB height during the maximal Valsalva maneuver in the SUI group were found to be significantly higher than that in healthy volunteers. Emax and Emean of PB negatively correlated with BMI during the maximal Valsalva maneuver (r = -0.277, P = 0.001 and r = -0.211, P = 0.014). ROC curve analysis demonstrated that PB perimeter of less than 12.68mm was strongly associated with SUI during the maximal Valsalva maneuver, and an Emax of less than 55.76 kPa had a 100% specificity in predicting SUI. SWE can quantify the elasticity of PB, identifying a significant difference between participants at rest and during Valsalva maneuver. In addition, the stiffness of the PB was significantly lower in women with SUI than in healthy women, which may provide a noninvasive clinical practice in SUI prediction.

Probing and monitoring multiple forms of localised corrosion occurring concurrently on pipeline steels in marine environments

An electrode array probe, with a novel approach, has been specifically designed to enable the in-situ field monitoring of multiple forms of localised corrosion of steel exposed to marine environments. The initiation and propagation of localised corrosion within the crevice area as well as at the steel weldment were visualised and evaluated over one-year field exposure at two different marine locations in Australia. The results show the varied initiation and propagation behaviour of crevice corrosion and weldment corrosion on steel, which provide experimental evidence for ‘bi-modal’ behaviour and the change-over of corrosion modes in extended periods of marine exposure.

Quantitative detection of axial defects in pipelines based on modified multi-mode total focusing method (MTFM)

The axial defects in pipelines are hard to detect effectively with the conventional multi-mode total focusing method (MTFM). The inner and outer curved surfaces of pipelines induce beam divergence, reducing focusing performance and introducing imaging distortion and errors. In this paper, the MTFM employed for inspecting flat plates is modified in consideration of the influences of pipe curvature on the ray paths of direct, half-skip and full-skip mode waves. The corresponding travel times are recalculated and used for performing delay-and-sum (DAS) beamforming, achieving the profile reconstruction and quantitative detection of axial defects. The simulation and experiments were implemented on the carbon steel pipeline with 100 mm outer radius and 20 mm wall thickness. The phased array (PA) probe with 32 elements and 5 MHz central frequency and the 55° curved wedge were adopted to detect the inner-wall axial defects in pipeline. The profiles of the planar defects with a length of 5 mm and orientation angles of −45°∼45° were well reconstructed by modified MTFM, and the measurement errors of flaw lengths, orientation angles and tip depths were no more than 16.6 %, 5.1° and 4.0 % after correction, respectively. Further simulated and experimental results indicate that the internal axial defects can also be detected and quantified by modified MTFM. Finally, the influences of pipe curvature on modified MTFM are discussed by simulation.

Real-time electro-mechanical profiling of dynamically beating human cardiac organoids by coupling resistive skins with microelectrode arrays

Cardiac organoids differentiated from induced pluripotent stem cells are emerging as a promising platform for pre-clinical drug screening, assessing cardiotoxicity, and disease modelling. However, it is challenging to simultaneously measure mechanical contractile forces and electrophysiological signals of cardiac organoids in real-time and in-situ with the existing methods. Here, we present a biting-inspired sensory system based on a resistive skin sensor and a microelectrode array. The bite-like contact can be established with a micromanipulator to precisely position the resistive skin sensor on the top of the cardiac organoid while the 3D microneedle electrode array probes from underneath. Such reliable contact is key to achieving simultaneous electro-mechanical measurements. We demonstrate the use of our system for modelling cardiotoxicity with the anti-cancer drug doxorubicin. The electro-mechanical parameters described here elucidate the acute cardiotoxic effects induced by doxorubicin. This integrated electro-mechanical system enables a suite of new diagnostic options for assessing cardiac organoids and tissues.

Ultrasound 3D beam-forming with distributed electrodes and frequency sub-band compounding

Abstract Array probes are commonly used in ultrasound equipment. These are transducers arranged in an array. This system requires multiple transmitter and receiver circuits, making it an expensive system; three-dimensional ultrasound imaging requires a two-dimensional array, which is even more expensive and difficult to popularize. We propose an imaging system with a single transducer and a single transmitter/receiver circuit for low-cost implementation of ultrasound imaging. The system uses a distributed electrode, which consists of multiple electrodes on a single transducer. Each electrode is connected to a single transmit/receive circuit. In this paper, we evaluate the performance of the proposed and existing array probe systems and systems by simulation.