Novel CO2 loaded nanoparticle ultrasound-activated contrast agent: A potential urinary catheter-free modality to detect vesicoureteral reflux

Journal of Pediatric Urology · 2025-01-08 · 1 citations

Handheld Large 2-D Array With Azimuthal Planewave and Row-Multiplexed Elevation Beamforming Enabled by Local ASIC Electronics

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · 2025-05-16 · 6 citations

Large-aperture 2-D arrays benefit from improved lateral resolution at depth, due to the dependence of beamwidth on the inverse of the aperture width, and improved contrast resolution due to electronic focusing. We have been developing modular large-aperture multirow 1024 (64 azimuth $\times 16$ elevation) element, 2-D arrays based on custom-designed and locally integrated application-specific integrated circuit (ASIC) multiplexing devices. The implemented handheld large-array prototype probe for human imaging consists of multiple rows with multiplexed synthetic aperture in elevation and planewave transmits in azimuth. The pitch of the acoustic array is $650~\mu $ m in azimuth by $1000~\mu $ m in elevation, with a 2.4 MHz fractional bandwidth (FBW =88%) center frequency and total active aperture of $42\times 16$ mm. We interfaced the large aperture array and multiplexing ASICs, along with local preamplifier devices for improved sensitivity, and a local FPGA for digital ASIC control, to a configurable ultrasound imaging platform and demonstrate 2-D orthogonal and full 3D beamformed imaging. The implemented imaging prototype includes local buffering for improved sensitivity of the high-impedance 2-D array elements, and realizes penetration down to 140 mm, experimental lateral/axial resolution at 67 mm of 1.1/0.4 mm, and maximum experimental CNR of 2.1 for 8 mm cylindrical cysts and 1.7 for 10 mm spherical cysts. We demonstrate in vivo imaging of liver in human volunteers utilizing a hermetically sealed and safety-validated handheld prototype of the large 2-D array. Preliminary results are promising for clinical imaging in future studies.

PD55-08 SELECTIVE RELEASE OF CO2-LOADED NANOPARTICLES FOR VESICOURETERAL REFLUX IMAGING

The Journal of Urology · 2024-04-15

You have accessJournal of UrologyPediatrics VI (PD55)1 May 2024PD55-08 SELECTIVE RELEASE OF CO2-LOADED NANOPARTICLES FOR VESICOURETERAL REFLUX IMAGING Helal Syed, Callum Lavoie, Van Do, Christine Do, Travis Williams, Jesse Yen, and Andy Chang Helal SyedHelal Syed , Callum LavoieCallum Lavoie , Van DoVan Do , Christine DoChristine Do , Travis WilliamsTravis Williams , Jesse YenJesse Yen , and Andy ChangAndy Chang View All Author Informationhttps://doi.org/10.1097/01.JU.0001008908.82706.9f.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The current gold-standard technique for detection of vesicoureteral reflux (VUR) is the voiding cystourethrogram (VCUG), which can be problematic with the need for bladder catheterization and ionizing radiation. While contrast enhanced voiding urosonography avoids use of ionizing radiation, it still requires catheterization. We propose a new, catheter-free modality. The concept is to intravenously inject covalently bound CO2 nanoparticles that are filtered by the kidney and excreted into the urine. In the bladder, the nanoparticles are activated by ultrasound to produce CO2 bubbles. Any bubbles visualized in the ureters or kidneys will indicate VUR presence. We present our early preclinical data. METHODS: Polyethylenimine (PEI, 500-940 mg) was dissolved in solvent (DI water, ethylene glycol, or PBS; 10 mL), followed by dry ice (50 g) in a sealed Parr apparatus. Dry ice released CO2 and the reaction was stirred for 18 hours until it reached ambient temperature. A rubber balloon (simulating a bladder) was filled with either water only or the nanoparticle solution. We used a prototype 1.1 MHz spherically focused, air-backed transducer (focal depth: 55 mm) or a prototype unfocused 1.66 MHz air-backed transducer, a computer-controlled RF generator (JJ&A Instruments) to provide bubble sonication, and a Butterfly iQ imaging system to simultaneously visualize the bubbles produced. We used an electrical power of 10 W with 10% duty cycle (1 ms on, 9 ms off) for a period of 5 seconds. A 37 mm layer of pork belly was then interposed between the ultrasound transducers and the experiment repeated. RESULTS: Figure A shows nanoparticle and water solutions upon stimulation with ultrasound in the balloon-only model. Our work shows the potential to produce and visualize microbubbles when applied to CO2-loaded nanoparticles. Also, visualization was successful with a 37 mm thick layer of pork belly interposed between the ultrasound and balloon. CONCLUSIONS: We have demonstrated the ability to selectively release covalently bound CO2 nanoparticles and use CO2 bubbles as an ultrasound contrast agent. This is a major technical hurdle we have overcome in our quest to develop a catheter-free, radiation-free VCUG. Our next steps are to refine our nanoparticles, optimize ultrasound activation parameters, and test this modality in an animal model to detect VUR. Source of Funding: N/A © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e1153 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Helal Syed More articles by this author Callum Lavoie More articles by this author Van Do More articles by this author Christine Do More articles by this author Travis Williams More articles by this author Jesse Yen More articles by this author Andy Chang More articles by this author Expand All Advertisement PDF downloadLoading ...

2D Arrays

2023-11-20 · 1 citations

Real-time clinical use of three-dimensional (3D) imaging with two-dimensional (2D) ultrasonic arrays has been an important goal for many years. The successful realization of such arrays was difficult to achieve, requiring significant innovation and many years of development. Over the past several decades, array development for volumetric imaging has advanced from sparse arrays to fully sampled arrays with thousands of elements, and the overall level of integration of processing has increased very significantly. This chapter reviews the advantages of 2D arrays and details the challenges involved in their implementation. It begins with a review of transducer and array design fundamentals and then discusses the primary issues for 2D array development: the electrical impedance mismatch, requirement for dense interconnects, need for high-speed data acquisition (ADCs) and sub-aperture analog and digital beamforming. Then historical and recent solutions to these challenges are reviewed. These include the choice of piezoelectric composite and single-crystal materials, capacitive and piezoelectric micromachined ultrasonic transducers (cMUTs and pMUTS), sparse array design, and fully sampled arrays using high-voltage CMOS application-specific integrated circuits (ASICs). Finally, the future outlook and additional applications of 2D arrays are discussed.

Selective release of CO₂-loaded nanoparticles for vesicoureteral reflux imaging

2023-09-03

Vesicoureteral reflux (VUR) is a disorder affecting young children in which urine flows backwards from the bladder to the kidneys. This can have serious health consequences in children and thus it is important to diagnose VUR reliably. However, the current diagnostic tests involve physically and emotionally traumatizing catheterization of children to inject radiographically detectable contrast agents. We propose an ultrasound-based technique in which CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -loaded nanoparticles are injected intravenously and undetectable until targeted by ultrasound in the bladder to produce CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> bubbles. These bubbles can then be visualized with standard B mode imaging to determine flow direction, and thus detect VUR. This strategy allows the nanoparticles to be excreted by the kidneys and, if successful, eliminates the need for catheterization and radiation exposure.

Ultrasound Imaging Using the Coherence of Estimated Channel Data

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · 2022-05-23 · 1 citations

This article introduces a novel method to estimate the coherence of ultrasound channel data from beamformed radio frequency (RF) data. Estimates of ultrasound channel data are obtained by spatially filtering acquired RF data in the frequency domain. The frequency response of the spatial filters yields outputs similar to frequency domain representations of individual channel signals. This technique performs multiple normalized cross-correlations from the outputs of multiple spatial filters. The coefficients are summed together for each pixel in the coherence-based image. Simulation results using a 64 element 2.5-MHz phased array showed an improvement in contrast-to-noise ratio (CNR) of 67%-93% and a 125%-183% improvement in speckle signal-to-noise ratio (SNR) compared with standard beamformed data. Experimental CNR using a tissue-mimicking phantom showed improvement of 43%-58%, and experimentalSNR improvement was 23%-154%. Comparisons to a previously coherence method, short-lag spatial coherence, are also presented. Preliminary in vivo images of the heart and gall bladder are also shown. This method improves CNR enabling improved visualization of anechoic regions such as cyst and blood vessels.

Boundary Array Transducer Combined with Coherence Estimation of Channel Data

2021-09-11

Recent studies suggest that ultrasound can be used for serial monitoring to guide therapeutic interventions at the point of care. A low-cost 3-D imaging system would ideally be suited for this application due to greater reproducibility over 2-D imaging. In our previous work, we performed a simulation study of a rectangular boundary array combined with nonlinear apodization methods to improve image contrast. In this work, we investigate the use of a novel coherence estimation technique to improve image contrast from a rectangular boundary array. This method is based in k-space, where the RF channel data is estimated from the beamformed RF data to estimate the coherence. Simulation and results showed that CECD combined with an RBA can provide near or better image quality in terms of the clutter level, contrast-to-noise ratio (CNR) and speckle signal-to-noise (SNR).

Mitral Valve Segmentation Using Robust Nonnegative Matrix Factorization

Journal of Imaging · 2021 · 6 citations

• Computer Science
• Artificial Intelligence
• Computer Science

Analyzing and understanding the movement of the mitral valve is of vital importance in cardiology, as the treatment and prevention of several serious heart diseases depend on it. Unfortunately, large amounts of noise as well as a highly varying image quality make the automatic tracking and segmentation of the mitral valve in two-dimensional echocardiographic videos challenging. In this paper, we present a fully automatic and unsupervised method for segmentation of the mitral valve in two-dimensional echocardiographic videos, independently of the echocardiographic view. We propose a bias-free variant of the robust non-negative matrix factorization (RNMF) along with a window-based localization approach, that is able to identify the mitral valve in several challenging situations. We improve the average f1-score on our dataset of 10 echocardiographic videos by 0.18 to a f1-score of 0.56.

Gated Transmit and Fresnel-Based Receive Beamforming With a Phased Array for Low-Cost Ultrasound Imaging

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · 2021 · 3 citations

• Computer Science
• Computer Science
• Electronic engineering

Low-cost ultrasound imaging systems are desired for many applications outside of radiology and cardiology departments. By making ultrasound systems smaller and lower cost, the use of ultrasound has spread from these mainstays to other areas of the hospital such as emergency departments and critical care. To further miniaturize and reduce the cost of ultrasound systems, we have investigated novel Fresnel-based beamforming methods to reduce front-end hardware requirements. Previous studies with linear and curvilinear arrays demonstrated comparable imaging performance using Fresnel-based beamforming versus delay-and-sum (DAS) beamforming. In this work, we extend Fresnel-based beamforming to phased arrays with beam steering. To accomplish this in transmit mode, we introduce a technique called a gated transmit beamformer where multicycle bursts are gated using multiplexers. In receive mode, a 64-element 2.5-MHz phased array is broken up into four 16-element subapertures, and each subaperture performs Fresnel beamforming before a final beamforming step is done. Timing errors are inevitable with Fresnel-based beamforming leading to higher sidelobe and clutter levels. To suppress sidelobe and clutter contributions, we also combine this with our previous technique, dual apodization with cross correlation (DAX) to improve contrast. Field II simulations are performed to evaluate spatial resolution and contrast-to-noise ratio and compared to standard DAS beamforming. Fresnel-based and gated transmit beamforming is also implemented using synthetic aperture data from tissue-mimicking phantoms. Lastly, a hardware proof-of-concept (PoC) Fresnel beamformer was designed, assembled, and evaluated with images from tissue-mimicking phantoms and initial in vivo images.

Active Damping of Air-backed Ultrasonic Transducers Using Arbitrary Waveform Generators

2020-09-07 · 2 citations

Ultrasound technologies such as high-intensity focused ultrasound and acoustic radiation force imaging require advanced or sophisticated transducer designs. Oftentimes, these designs have transducer requirements of wide power ranges, high sensitivity, and broad bandwidth. However, it would often times be desirable to use the same transducer for both. The objective of this proof-of-concept study is to demonstrate the feasibility of using active damping of air-backed, narrowband transducers to achieve broadband capability. Active damping is accomplished through the use of arbitrary waveform generators to cancel subsequent oscillations beyond the initial excitation. A modified 1-D KLM model written in Matlab is used to guide the design of the waveforms. Optimization of the waveforms is applied to the KLM model using minimization function that minimizes ripple. In the model, - 3 dB transmitted bandwidth increased from 10% to 44% for 1.5-cycle excitation and 11.4% to 63.8% for 1-cycle excitation. Comparable increases in bandwidth were also observed experimentally.