2D Probe Research Articles

Three-dimensional ultrasound matrix imaging

Matrix imaging paves the way towards a next revolution in wave physics. Based on the response matrix recorded between a set of sensors, it enables an optimized compensation of aberration phenomena and multiple scattering events that usually drastically hinder the focusing process in heterogeneous media. Although it gave rise to spectacular results in optical microscopy or seismic imaging, the success of matrix imaging has been so far relatively limited with ultrasonic waves because wave control is generally only performed with a linear array of transducers [1]. In this talk, we will extend ultrasound matrix imaging to a 3D geometry [2]. Switching from a 1D to a 2D probe enables a sharper estimation of the transmission matrix that links each transducer and each medium voxel. Here, we first present an experimental proof of concept on a tissue-mimicking phantom through ex vivo tissues and then show the potential of our reflection matrix approach for transcranial imaging, with applications to ultrasound localization microscopy of a sheep brain [3]. [1] W. Lambert et al., Proc. Natl. Ac. Sci. U. S. A. 117, 14645–14656 (2020) [2] F. Bureau et al., Nat. Commun. 14, 6793 (2023) [3] F. Bureau, L. Denis et al., (to be submitted).

223 An Artificial Intelligence Framework for Brain Tumor Delineation in Intraoperative Ultrasound

INTRODUCTION: Automated delineation of gliomas in intraoperative ultrasound (iUS) could provide timely information to surgeons. While artificial intelligence (AI) frameworks have shown promising results for delineating gliomas in preoperative MRI, automated delineation in iUS remains a challenging and open problem. METHODS: A deep learning algorithm was developed to automatically delineate gliomas in intraoperative ultrasound. Instead of using time-consuming manual delineations from experts, the algorithm was developed using MR-based automated delineations. First, a MR nnUnet was trained for delineating gliomas in 3D preoperative MRI using an annotated public dataset (N=1000; RSNA-ASNR-MICCAI-BraTS 2021). Then, this algorithm delineated gliomas in preoperative MRI of patients (N = 84) in whom pre-dural opening 3D iUS reconstructed from a tracked handheld 2D probe was also acquired. To obtain the MR-based delineations in iUS, preoperative MRI and iUS were aligned using NiftyReg. Finally, a 3D iUS nnUnet was trained using a random subset (N = 78) of this pseudo-annotated iUS dataset. The method was assessed on the remaining test set (N = 943 slices from 6 volumes), with a treating neurosurgeon delineating gliomas in 2D iUS only and then in 2D iUS and aligned MR slices to obtain gold-standard delineations. RESULTS: The median Dice scores of the nnUnet and the neurosurgeon were respectively 78.6% (IQ:15.5%) and 84.3% (IQ: 21.1%) against the gold-standard delineations. In this preliminary study, the network's performance was comparable to the neurosurgeon's (two paired one-sided tests, equivalence margin:5%, p<1e-5, N = 943), with rapid delineation (<10 second) of 3D iUS (95-216 slices) compared to neurogeons (32-93 minutes), making automated delineation practical during surgery. CONCLUSIONS: The results demonstrate the feasibility of using AI-based methods for automated delineation of brain tumors in iUS, which could improve surgical outcomes by providing real-time information to surgeons.

Optimal Design of Sparse Matrix Phased Array Using Simulated Annealing for Volumetric Ultrasonic Imaging with Total Focusing Method.

The total focusing method (TFM) is often considered to be the 'gold standard' for ultrasonic imaging in the field of nondestructive testing. The use of matrix phased arrays as probes allows for high-resolution volumetric TFM imaging. Conventional TFM imaging involves the use of full matrix capture (FMC) for ultrasonic signals acquisition, but in the case of a matrix phased array, this approach is associated with a huge volume of data to be acquired and processed. This severely limits the frame rate of volumetric imaging with 2D probes and necessitates the use of high-end equipment. Thus, the aim of this research was to develop a novel design method for determining the optimal sparse 2D probe configuration for specific conditions of ultrasonic imaging. The developed approach is based on simulated annealing and involves implementing the solution of the sparse matrix phased array layout optimization problem. In order to implement simulated annealing for the aforementioned task, its parameters were set, the acceptance function was introduced, and the approaches were proposed to compute beam directivity diagrams of sparse matrix phased arrays in TFM imaging. Experimental studies have shown that the proposed approach provides high-quality volumetric imaging with a decrease in data volume of up to 84% compared to that obtained using the FMC data acquisition method.

Added value of 3D ultrasound image-guided hepatic interventions by X matrix technology

BackgroundImage-guided hepatic interventions are integral to the management of infective and neoplastic liver lesions. Over the past decades, 2D US was used for guidance of hepatic interventions; with the recent advances in US technology, 3D US was used to guide the hepatic interventions. This study aimed to illustrate the added value of 3D image-guided hepatic interventions by X matrix technology.MethodsThis prospective study was performed on 100 patients that were divided into two groups: group A which included 50 patients who were managed by using 2D US probe guidance, and group B which included 50 patients who were managed by using 3D X matrix US probe guidance. Thermal ablation was done for 70 patients; 40 radiofrequency ablation (RFA) (20 by the 2D probe and 20 by the 3D X matrix probe) and 30 microwave ablation (MWA) (15 by the 2D probe and 15 by the 3D X matrix probe). Chemical ablation (PEI) was done for 20 patients (ten by the 2D probe and ten by the 3D X matrix probe). Drainage of hepatic collections and biopsy from undiagnosed hepatic focal lesions were done for ten patients (five by the 2D probe and five by the 3D X matrix probe).ResultsThe efficacy of US-guided hepatic interventions by 3D X matrix probe was higher than the 2D probe but not significantly higher, with a p value of 0.705, 0.5428 for RFA and MWA, respectively, 0.5312 for PEI, and 0.2918 for drainage of hepatic collections and biopsy. The complications related to the use of the 3D X matrix probe were significantly lower than the 2D probe with a p value of 0.003. The timing of the procedure was shorter by the usage of a 3D X matrix probe in comparison with the 2D probe with a p value of 0.08, 0.34 for RFA and PEI and significantly shorter for MWA and drainage of hepatic collection, biopsy with a p value of 0.02, 0.001, respectively.Conclusions3D US-guided hepatic interventions by X matrix probe have better efficacy, less complication, and shorter time of procedure than the 2D US-guided hepatic interventions.

Three-dimensional ultrasound matrix imaging

Matrix imaging paves the way towards a next revolution in wave physics. Based on the response matrix recorded between a set of sensors, it enables an optimized compensation of aberration phenomena and multiple scattering events that usually drastically hinder the focusing process in heterogeneous media. Although it gave rise to spectacular results in optical microscopy or seismic imaging, the success of matrix imaging has been so far relatively limited with ultrasonic waves because wave control is generally only performed with a linear array of transducers. In this paper, we extend ultrasound matrix imaging to a 3D geometry. Switching from a 1D to a 2D probe enables a much sharper estimation of the transmission matrix that links each transducer and each medium voxel. Here, we first present an experimental proof of concept on a tissue-mimicking phantom through ex-vivo tissues and then, show the potential of 3D matrix imaging for transcranial applications.

An LF-NMR homogeneous immunoassay for Vibrio parahaemolyticus based on superparamagnetic 2D nanomaterials

In this work, a sensitive low field nuclear magnetic resonance (LF-NMR) homogeneous immunoassay, also called magnetic resonance switch (MRSw) sensor, for Vibrio parahaemolyticus (VP) was developed. Superparamagnetic 2D nanomaterial was designed and used as the magnetic probe of MRSw sensor. It was GO@SPIONs&Ab, a composite nanomaterial with many superparamagnetic Fe3O4 nanoparticles (SPIONs) providing a magnetic signal and VP antibody (Ab) specifically recognizing the target VP evenly distributed on the surface of GO. The presence of VP controllably changed the aggregation state of the probe, eliminating the uncertainty of MRSw sensor type, and thus then achieving a regular variation of transverse relaxation time T2 and ensuing quantitative detection of VP. Triple signal enhancement of the MRSw sensor was obtained due to the application of the designed 2D probe, by increasing the number of SPIONs, improving the magnetic intensity and susceptibility, and forming a synergistic effect. Under optimized experimental conditions, VP could be detected with satisfied sensitivity, selectivity, precision, accuracy, and stability, even in turbid real samples. LOQ for VP was 10 CFU/mL. This detection principle is widely applicable, providing an idea for the construction of highly sensitive MRSw sensors.

Efficient Three-Dimensional DNA Nanomachine Guided by a Robust Tetrahedral DNA Nanoarray Structure for the Rapid and Ultrasensitive Electrochemical Detection of Matrix Metalloproteinase 2.

Herein, a giant-sized DNA nanoarray was subtly assembled by two kinds of independent tetrahedral DNA structures as the DNA track for a multi-armed three-dimensional (3D) DNA nanomachine to perform signal transduction and amplification efficiently, which was developed as an electrochemical biosensor for the rapid and ultrasensitive detection of matrix metalloproteinase 2 (MMP-2). Impressively, in contrast to conventional DNA walkers with inefficiency, which walked on random DNA tracks composed of a two-dimensional (2D) probe or a one-dimensional (1D) single-stranded (ss)DNA probe, the multi-armed 3D DNA nanomachine from exonuclease III (Exo III) enzyme-assisted target recycling amplification would be endowed with faster reaction speed and better walking efficiency because of the excellent rigidity and orderliness of the tetrahedral DNA nanoarray structure. Once the hairpin H3-label with the signal substance ferrocene (Fc) was added to the modified electrode surface, the multi-armed 3D DNA nanomachine would be driven to move along the well-designed nanoarray tracks by toehold-mediated DNA strand displacement, resulting in most of the ferrocene (Fc) binding to the electrode surface and a remarkable increase in electrochemical signals within 60 min. As a proof of concept, the prepared biosensor attained a low detection limit of 11.4 fg/mL for the sensitive detection of the target MMP-2 and was applied in Hela and MCF-7 cancer cell lysates. As a result, this strategy provided a high-performance sensing platform for protein detection in tumor diagnosis.

A guiding approach of Ultrasound scan for accurately obtaining standard diagnostic planes of fetal brain malformation.

Standard planes (SPs) are crucial for the diagnosis of fetal brain malformation. However, it is very time-consuming and requires extensive experiences to acquire the SPs accurately due to the large difference in fetal posture and the complexity of SPs definitions. This study aims to present a guiding approach that could assist sonographer to obtain the SPs more accurately and more quickly. To begin with, sonographer uses the 3D probe to scan the fetal head to obtain 3D volume data, and then we used affine transformation to calibrate 3D volume data to the standard body position and established the corresponding 3D head model in 'real time'. When the sonographer uses the 2D probe to scan a plane, the position of current plane can be clearly show in 3D head model by our RLNet (regression location network), which can conduct the sonographer to obtain the three SPs more accurately. When the three SPs are located, the sagittal plane and the coronal planes can be automatically generated according to the spatial relationship with the three SPs. Experimental results conducted on 3200 2D US images show that the RLNet achieves average angle error of the transthalamic plane was 3.91±2.86°, which has a obvious improvement compared other published data. The automatically generated coronal and sagittal SPs conform the diagnostic criteria and the diagnostic requirements of fetal brain malformation. A guiding scanning method based deep learning for ultrasonic brain malformation screening is firstly proposed and it has a pragmatic value for future clinical application.

New insights on divertor parallel flows,E × B drifts, and fluctuations from in situ, two-dimensional probe measurement in the Tokamak à Configuration Variable

In situ, two-dimensional (2D) Langmuir probe measurements across a large part of the TCV outer divertor are reported in L-mode discharges with and without divertor baffles. This provides detailed insights into time averaged profiles, particle fluxes, and fluctuation behavior in different divertor regimes. The presence of the baffles is shown to substantially increase the divertor neutral pressure for a given upstream density and to facilitate the access to detachment, an effect that increases with plasma current. The detailed, 2D probe measurements allow for a divertor particle balance, including ion flux contributions from parallel flows and E × B drifts. The poloidal flux contribution from the latter is often comparable or even larger than the former, and the divertor parallel flow direction reverses in some conditions, pointing away from the target. In most conditions, the integrated particle flux at the outer target can be predominantly ascribed to ionization along the outer divertor leg, consistent with a closed-box approximation of the divertor. The exception is a strongly detached divertor, achieved here only with baffles, where the total poloidal ion flux even decreases towards the outer target, indicative of significant plasma recombination. The most striking observation from relative density fluctuation measurements along the outer divertor leg is the transition from poloidally uniform fluctuation levels in attached conditions to fluctuations strongly peaking near the X-point when approaching detachment.

Comparison of Anorectal Function as Measured with High-Resolution and High-Definition Anorectal Manometry

Introduction: Anorectal manometry (ARM) provides comprehensive assessment of pressure activity in the rectum and anal canal. Absolute pressure values might depend on the catheter used. Objective: Our aim was to compare the results obtained by different anorectal catheters in children with functional anorectal disorders. Methods: Children diagnosed with functional defecation disorders based on the Rome IV criteria were prospectively enrolled. ARM was performed in the supine position successively using 2 different probes in each patient in random order. Resting, squeeze pressures, and bear-down maneuver variables obtained by high-resolution (2-dimensional [2D]) and high-definition (3-dimensional [3D]) catheters were compared. Results: We prospectively included 100 children {mean age 7.5 [standard deviation (SD) ± 4.3] years; 62 boys}. Mean resting pressures were significantly higher when measured with the 3D than with the 2D catheter (71 [SD ± 19.4] vs. 65 [SD ± 20.1] mm Hg, respectively; p = 0.000). Intrarectal pressure measured by 3D and 2D catheters was similar (35 vs. 39 mm Hg, respectively; p = 0.761), but the percent of anal relaxation appeared to be higher for the 3D than for the 2D probe (12 vs. 5%, respectively; p = 0.002). Dyssynergic defecation (DD) was diagnosed in 41/71 patients (57.7%) using the 3D probe and in 51/71 children (71.8%) using the 2D probe (p = 0.044). Cohen’s kappa showed only fair agreement between the catheters (κ = 0.40) in diagnosis of DD. Conclusions: Our study demonstrated significantly different values of pressures obtained with different types of catheters. Normal ranges for conventional manometry cannot be applied to high-resolution systems, and results obtained by different types of manometry cannot be compared without adjustments (NCT02812823).

Pose‐invariant face recognition based on matching the occlusion free regions aligned by 3D generic model

Face recognition systems perform accurately in a controlled environment, but an unconstrained environment dramatically degrades their performance. In this study, a novel pose‐invariant face recognition system is proposed based on the occlusion free regions. This method utilises a gallery set of frontal face images and can handle large pose variations. For a 2D probe face image with an arbitrary pose, the head pose is first obtained using a robust head pose estimation method. Then, this 2D face image is normalised by a novel 3D modelling method from a single input image. In consequence, pose invariant face recognition is converted to a frontal face recognition problem. The 3D structure is reconstructed using a new method based on the estimated head pose and only one facial feature point, which is significantly reduced in comparison with the number of landmarks used in previous methods. According to the estimated poses, occlusion free regions are extracted from normalised images as feature extraction. Finally, face matching and recognition is performed using these regions from normalised test images and the corresponding regions of gallery images. Experimental results on FERET and CAS‐PEAL‐R1 databases demonstrate that the proposed method outperforms other methods, and it is robust and efficient.

Versatile high-speed confocal microscopy using a single laser beam.

We present a new flexible high speed laser scanning confocal microscope and its extension by an astigmatism particle tracking velocimetry (APTV) device. Many standard confocal microscopes use either a single laser beam to scan the sample at a relatively low overall frame rate or many laser beams to simultaneously scan the sample and achieve a high overall frame rate. The single-laser-beam confocal microscope often uses a point detector to acquire the image. To achieve high overall frame rates, we use, next to the standard 2D probe scanning unit, a second 2D scan unit projecting the image directly onto a 2D CCD-sensor (re-scan configuration). Using only a single laser beam eliminates crosstalk and leads to an imaging quality that is independent of the frame rate with a lateral resolution of 0.235 µm. The design described here is suitable for a high frame rate, i.e., for frame rates well above the video rate (full frame) up to a line rate of 32 kHz. The dwell time of the laser focus on any spot in the sample (122 ns) is significantly shorter than those in standard confocal microscopes (in the order of milli- or microseconds). This short dwell time reduces phototoxicity and bleaching of fluorescent molecules. The new design opens up further flexibility and facilitates coupling to other optical methods. The setup can easily be extended by an APTV device to measure three dimensional dynamics while being able to show high resolution confocal structures. Thus, one can use the high resolution confocal information synchronized with an APTV dataset.

Technical Note: Assessment of electromagnetic tracking systems in a surgical environment using ultrasonography and ureteroscopy instruments for percutaneous renal access.

Electromagnetic tracking systems (EMTSs) have been proposed to assist the percutaneous renal access (PRA) during minimally invasive interventions to the renal system. However, the influence of other surgical instruments widely used during PRA (like ureteroscopy and ultrasound equipment) in the EMTS performance is not completely known. This work performs this assessment for two EMTSs [Aurora® Planar Field Generator (PFG); Aurora® Tabletop Field Generator (TTFG)]. An assessment platform, composed by a scaffold with specific supports to attach the surgical instruments and a plate phantom with multiple levels to precisely translate or rotate the surgical instruments, was developed. The median accuracy and precision in terms of position and orientation were estimated for the PFG and TTFG in a surgical environment using this platform. Then, the influence of different surgical instruments (alone or together), namely analogic flexible ureterorenoscope (AUR), digital flexible ureterorenoscope (DUR), two-dimensional (2D) ultrasound (US) probe, and four-dimensional (4D) mechanical US probe, was assessed for both EMTSs by coupling the instruments to 5-DOF and 6-DOF sensors. Overall, the median positional and orientation accuracies in the surgical environment were 0.85mm and 0.42° for PFG, and 0.72mm and 0.39° for TTFG, while precisions were 0.10mm and 0.03° for PFG, and 0.20mm and 0.12° for TTFG, respectively. No significant differences were found for accuracy between EMTSs. However, PFG showed a tendency for higher precision than TTFG. AUR, DUR, and 2D US probe did not influence the accuracy and precision of both EMTSs. In opposition, the 4D probe distorted the signal near the attached sensor, making readings unreliable. Ureteroscopy- and ultrasonography-assisted PRA based on EMTS guidance are feasible with the tested AUR or DUR together with the 2D probe. More studies must be performed to evaluate the probes and ureterorenoscopes' influence before their use in PRA based on EMTS guidance.

Visual Immunoassays: Layered Aggregation with Steric Effect: Morphology‐Homogeneous Semiconductor MoS2 as an Alternative 2D Probe for Visual Immunoassay (Small 7/2018)

Visual Immunoassays: Layered Aggregation with Steric Effect: Morphology‐Homogeneous Semiconductor MoS₂ as an Alternative 2D Probe for Visual Immunoassay (Small 7/2018)

Layered Aggregation with Steric Effect: Morphology-Homogeneous Semiconductor MoS2 as an Alternative 2D Probe for Visual Immunoassay.

Liquid-phase exfoliation routes unavoidably generate 2D nanostructures with inhomogeneous morphologies. Herein, thickness-dependent sorting of exfoliated nanostructures is achieved via a treatment of differential-zone centrifugation in the surfactant aqueous phase. With this approach, homogeneous MoS2 nanosheets are obtained, and due to the intrinsic semiconducting characteristics, those 2D nanosheets are endowed with desired optical properties, rivaling classic gold nanoparticles in sensing applications. Furthermore, MoS2 nanosheets with high uniformity and chemical inertness are coupled with proteins, exhibiting high performance in stability and anti-interferences for bioanalysis. As a consequence of aggregation-induced steric effect, distinguishing running shifts of antibody-anchored conjugates in gel electrophoresis are visually responsive to those specific antigens. This assay enables the easy and fast monitoring of tumor biomarkers just according to "naked-eye" identification of band location in electrophoresis results, which are presented by an alternative visual probe of 2D MoS2 -protein conjugates. The developed visual immunoassay with the synergistic effect of gel electrophoresis techniques and 2D semiconductors pushes significant progress in "home-made" tests for disease early diagnosis.

Glypican-3-targeted precision diagnosis of hepatocellular carcinoma on clinical sections with a supramolecular 2D imaging probe.

The ability of chemical tools to effectively detect malignancy in frozen sections removed from patients during surgery is important for the timely determination of the subsequent surgical program. However, current clinical methods for tissue imaging rely on dye-based staining or antibody-based techniques, which are sluggish and complicated.Methods: Here, we have developed a 2D material-based supramolecular imaging probe for the simple, rapid yet precise diagnosis of hepatocellular carcinoma (HCC). The 2D probe is constructed through supramolecular self-assembly between a water soluble, fluorescent peptide ligand that selectively targets glypican-3 (GPC-3, a specific cell-surface biomarker for HCC) and 2D molybdenum disulfide that acts as a fluorescence quencher as well as imaging enhancer.Results: We show that the 2D imaging probe developed with minimal background fluorescence can sensitively and selectively image cells overexpressing GPC-3 over a range of control cells expressing other membrane proteins. Importantly, we demonstrate that the 2D probe is capable of rapidly (signal became readable within 1 min) imaging HCC tissues over para-carcinoma regions in frozen sections derived from HCC patients; the results are in accordance with those obtained using traditional clinical staining methods.Conclusion: Compared to conventional staining methods, which are laborious (e.g., over 30 min is needed for antibody-based immunosorbent assays) and complex (e.g., diagnosis is based on discrimination of the nucleus morphology of cancer cells from that of normal cells), our probe, with its simplicity and quickness, might become a promising candidate for tumor-section staining as well as fluorescence imaging-guided surgery.

Two-dimensional probe absorption in coupled quantum dots

We investigate the two-dimensional (2D) probe absorption in coupled quantum dots. It is found that, due to the position-dependent quantum interference effect, the 2D optical absorption spectrum can be easily controlled via adjusting the system parameters. Thus, our scheme may provide some technological applications in solid-state quantum communication.

Performance of a Multispectral Optoacoustic Tomography (MSOT) System equipped with 2D vs. 3D Handheld Probes for Potential Clinical Translation

A handheld approach to optoacoustic imaging is essential for the clinical translation. The first 2- and 3-dimensional handheld multispectral optoacoustic tomography (MSOT) probes featuring real-time unmixing have recently been developed. Imaging performance of both probes was determined in vitro and in a brain melanoma metastasis mouse model in vivo. T1-weighted MR images were acquired for anatomical reference. The limit of detection of melanoma cells in vitro was significantly lower using the 2D than the 3D probe. The signal decrease was more profound in relation to depth with the 3D versus the 2D probe. Both approaches were capable of imaging the melanoma tumors qualitatively at all time points. Quantitatively, the 2D approach enabled closer anatomical resemblance of the tumor compared to the 3D probe, particularly at depths beyond 3mm. The 3D probe was shown to be superior for rapid 3D imaging and, thus, holds promise for more superficial target structures.

Preliminary design of an actuated imaging probe for generation of additional visual cues in a robotic surgery.

The aim of this study was to enhance the visual feedback of surgeons, during robotic surgeries, by designing and developing an actuated 2D imaging probe, which is used in conjunction with the traditional stereoscopic camera of the da Vinci surgical system. The probe provides the surgeon with additional visual cues, overcoming visualization constraints encountered during certain scenarios of robot-assisted minimally invasive surgery. The actuated imaging probe is implemented as a master-slave tele-manipulated system, and it is designed to be compatible with the da Vinci surgical system. The detachable probe design enables it to be mounted on any of the EndoWrist(®) instruments of the robot and is controlled by the surgeon using a custom-made pedal system. The image from the 2D probe is rendered along with the stereoscopic view on the surgeon's console. The experimental results demonstrate the effectiveness of the proposed actuated imaging probe when used as an additional visualization channel and in surgical scenarios presenting visual problems due to tissue occlusion. The study shows the potential benefits of an additional actuated imaging probe when used in conjunction with traditional surgical instruments to perform surgical tasks requiring visualization from multiple orientations and workspaces.

Efficient 2D probe absorption spectrum in nanodiamond nitrogen vacancy centers

In this letter, we investigate the 2D probe absorption spectrum in nanodiamond nitrogen vacancy centers under optical excitation. Different cases of the standing waves–matter interaction are considered to study the spatial dependence of probe absorption. It is shown that due to the quantum interference between different quantum paths in this system, various structures of localization as lattice-like, cross-like, circular-like and ‘’-like patterns can be designed by adjusting the detuning intensities and Zeeman shift.