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Olomodosi A, Strassle Rojas S, Vu P, Lindsey BD. 2D array imaging system for mechanically-steered, forward-viewing ultrasound guidewire. ULTRASONICS 2024; 142:107398. [PMID: 39018696 PMCID: PMC11298298 DOI: 10.1016/j.ultras.2024.107398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 06/28/2024] [Accepted: 07/02/2024] [Indexed: 07/19/2024]
Abstract
Approximately 4 million people with peripheral artery disease (PAD) present with critical limb ischemia each year, requiring urgent revascularization to avoid loss of limb. Minimally-invasive (i.e. endovascular) revascularization is preferable due to increased recovery time and increased risk of complications associated with open surgery. However, 40% of people with PAD also have chronic total occlusions (CTOs), resulting in > 20% of revascularization procedures failing when CTOs are present. A steerable robotic guidewire with integrated forward-viewing imaging capabilities would allow the guidewire to navigate through tortuous vasculature and facilitate crossing CTOs in revascularization procedures that currently fail due to inability to route the guidewire. The robotic steering capabilities of the guidewire can be leveraged for 3D synthetic aperture imaging with a simplified, low element count, forward-viewing 2D array on the tip of the mechanically-steered guidewire. Images can then be formed using a hybrid beamforming approach, with focal delays calculated for each element on the tip of the guidewire and for each physical location to which the robotically-steered guidewire is steered. Unlike synthetic aperture imaging with a steerable guidewire having only a single element transducer, an array with even a small number of elements can allow estimation of blood flow and physiological motion in vivo. A miniature, low element count 2D array transducer with 9 total elements (3 × 3) having total dimensions of 1.5 mm × 1.5 mm was designed to operate at 17 MHz. A proof-of-concept 2D array transducer was fabricated and characterized acoustically. The developed array was then used to image a wire target, a peripheral stent, and an ex vivo porcine iliac artery. Images were formed using the described synthetic aperture beamforming strategy. Acoustic characterization showed a mean resonance frequency of 17.6 MHz and a -6 dB bandwidth of 35%. Lateral and axial resolution were 0.271 mm and 0.122 mm, respectively, and an increase in SNR of 4.8 dB was observed for the 2D array relative to the single element case. The first 2D array imaging system utilizing both mechanical and electronic steering for guidewire-based imaging was developed and demonstrated. A 2D array imaging system operating on the tip of the mechanically-steered guidewire provides improved frame rate and increases field of view relative to a single element transducer. Finally, 2D array and single element imaging were compared for introduced motion errors, with the 2D array providing a 46.1% increase in SNR, and 58.5% and 17.3% improvement in lateral and axial resolution, respectively, relative to single element guidewire imaging.
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Affiliation(s)
- Adeoye Olomodosi
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, United States
| | - Stephan Strassle Rojas
- Department of Electrical and Computer Engineering, Georgia Institute of Technology, United States
| | - Phuong Vu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, United States
| | - Brooks D Lindsey
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, United States; Department of Electrical and Computer Engineering, Georgia Institute of Technology, United States.
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Kreager BC, Wu H, Chang WY, Moon S, Mitchell J, Peng C, Huang CC, Muller M, Tian J, Jiang X. High-Performance PMN-PT Single-Crystal-Based 1-3 Composite Transducer Integrated with a Biopsy Needle. BIOSENSORS 2024; 14:74. [PMID: 38391993 PMCID: PMC10887013 DOI: 10.3390/bios14020074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/24/2024]
Abstract
To address the need for high-resolution imaging in lung nodule detection and overcome the limitations of the shallow imaging depth associated with high-frequency ultrasound and the complex structure of lung tissue, we successfully integrated 50 MHz ultrasound transducers with 18-gauge biopsy needles. Featuring a miniaturized size of 0.6 × 0.5 × 0.5 mm3, the 50 MHz micromachined 1-3 composite transducer was tested to perform mechanical scanning of a nodule within a lung-tissue-mimicking phantom in vitro. The high-frequency transducer demonstrated the ability to achieve imaging with an axial resolution of 30 μm for measuring nodule edges. Moreover, the integrated biopsy needle prototype exhibited high accuracy (1.74% discrepancy) in estimating nodule area compared to actual dimensions in vitro. These results underscore the promising potential of biopsy-needle-integrated transducers in enhancing the accuracy of endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNA) for clinical applications.
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Affiliation(s)
- Benjamin C. Kreager
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
| | - Huaiyu Wu
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
| | - Wei-Yi Chang
- CTS Advanced Materials, 4925 Indiana Ave, Lisle, IL 604532, USA; (W.-Y.C.); (J.T.)
| | - Sunho Moon
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
| | - Josh Mitchell
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
| | - Chang Peng
- School of Biomedical Engineering, ShanghaiTech University, Shanghai 201210, China;
| | - Chih-Chung Huang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan;
| | - Marie Muller
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
| | - Jian Tian
- CTS Advanced Materials, 4925 Indiana Ave, Lisle, IL 604532, USA; (W.-Y.C.); (J.T.)
| | - Xiaoning Jiang
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA; (B.C.K.); (H.W.); (S.M.); (J.M.); (M.M.)
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Jiang B, Wang L, Xu K, Hossbach M, Demir A, Rajan P, Taylor RH, Moghekar A, Foroughi P, Kazanzides P, Boctor EM. Wearable Mechatronic Ultrasound-integrated AR Navigation System for Lumbar Puncture Guidance. IEEE TRANSACTIONS ON MEDICAL ROBOTICS AND BIONICS 2023; 5:966-977. [PMID: 38779126 PMCID: PMC11107797 DOI: 10.1109/tmrb.2023.3319963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
As one of the most commonly performed spinal interventions in routine clinical practice, lumbar punctures are usually done with only hand palpation and trial-and-error. Failures can prolong procedure time and introduce complications such as cerebrospinal fluid leaks and headaches. Therefore, an effective needle insertion guidance method is desired. In this work, we present a complete lumbar puncture guidance system with the integration of (1) a wearable mechatronic ultrasound imaging device, (2) volume-reconstruction and bone surface estimation algorithms and (3) two alternative augmented reality user interfaces for needle guidance, including a HoloLens-based and a tablet-based solution. We conducted a quantitative evaluation of the end-to-end navigation accuracy, which shows that our system can achieve an overall needle navigation accuracy of 2.83 mm and 2.76 mm for the Tablet-based and the HoloLens-based solutions, respectively. In addition, we conducted a preliminary user study to qualitatively evaluate the effectiveness and ergonomics of our system on lumbar phantoms. The results show that users were able to successfully reach the target in an average of 1.12 and 1.14 needle insertion attempts for Tablet-based and HoloLens-based systems, respectively, exhibiting the potential to reduce the failure rates of lumbar puncture procedures with the proposed lumbar-puncture guidance.
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Affiliation(s)
- Baichuan Jiang
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Liam Wang
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Keshuai Xu
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Alican Demir
- Clear Guide Medical Inc., Baltimore, MD 21211, USA
| | | | - Russell H. Taylor
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Abhay Moghekar
- Department of Neurology, Johns Hopkins Medical Institute, Baltimore, MD 21205, USA
| | | | - Peter Kazanzides
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Emad M. Boctor
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
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Harper DJ, Kim Y, Gómez-Ramírez A, Vakoc BJ. Needle guidance with Doppler-tracked polarization-sensitive optical coherence tomography. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:102910. [PMID: 37799938 PMCID: PMC10548115 DOI: 10.1117/1.jbo.28.10.102910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 08/25/2023] [Accepted: 09/22/2023] [Indexed: 10/07/2023]
Abstract
Significance Optical coherence tomography (OCT) can be integrated into needle probes to provide real-time navigational guidance. However, unscanned implementations, which are the simplest to build, often struggle to discriminate the relevant tissues. Aim We explore the use of polarization-sensitive (PS) methods as a means to enhance signal interpretability within unscanned coherence tomography probes. Approach Broadband light from a laser centered at 1310 nm was sent through a fiber that was embedded into a needle. The polarization signal from OCT fringes was combined with Doppler-based tracking to create visualizations of the birefringence properties of the tissue. Experiments were performed in (i) well-understood structured tissues (salmon and shrimp) and (ii) ex vivo porcine spine. The porcine experiments were selected to illustrate an epidural guidance use case. Results In the porcine spine, unscanned and Doppler-tracked PS OCT imaging data successfully identified the skin, subcutaneous tissue, ligament, and epidural spaces during needle insertion. Conclusions PS imaging within a needle probe improves signal interpretability relative to structural OCT methods and may advance the clinical utility of unscanned OCT needle probes in a variety of applications.
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Affiliation(s)
- Danielle J. Harper
- Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
- Harvard Medical School, Boston, Massachusetts, United States
| | - Yongjoo Kim
- Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
- Harvard Medical School, Boston, Massachusetts, United States
| | - Alejandra Gómez-Ramírez
- Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
- Universidad Nacional de Colombia sede Medellín, School of Physics, Medellín, Colombia
| | - Benjamin J. Vakoc
- Massachusetts General Hospital, Wellman Center for Photomedicine, Boston, Massachusetts, United States
- Harvard Medical School, Boston, Massachusetts, United States
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, United States
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Collins GC, Rojas SS, Bercu ZL, Desai JP, Lindsey BD. Supervised segmentation for guiding peripheral revascularization with forward-viewing, robotically steered ultrasound guidewire. Med Phys 2023; 50:3459-3474. [PMID: 36906877 PMCID: PMC10272103 DOI: 10.1002/mp.16350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 01/19/2023] [Accepted: 02/26/2023] [Indexed: 03/13/2023] Open
Abstract
BACKGROUND Approximately 500 000 patients present with critical limb ischemia (CLI) each year in the U.S., requiring revascularization to avoid amputation. While peripheral arteries can be revascularized via minimally invasive procedures, 25% of cases with chronic total occlusions are unsuccessful due to inability to route the guidewire beyond the proximal occlusion. Improvements to guidewire navigation would lead to limb salvage in a greater number of patients. PURPOSE Integrating ultrasound imaging into the guidewire could enable direct visualization of routes for guidewire advancement. In order to navigate a robotically-steerable guidewire with integrated imaging beyond a chronic occlusion proximal to the symptomatic lesion for revascularization, acquired ultrasound images must be segmented to visualize the path for guidewire advancement. METHODS The first approach for automated segmentation of viable paths through occlusions in peripheral arteries is demonstrated in simulations and experimentally-acquired data with a forward-viewing, robotically-steered guidewire imaging system. B-mode ultrasound images formed via synthetic aperture focusing (SAF) were segmented using a supervised approach (U-net architecture). A total of 2500 simulated images were used to train the classifier to distinguish the vessel wall and occlusion from viable paths for guidewire advancement. First, the size of the synthetic aperture resulting in the highest classification performance was determined in simulations (90 test images) and compared with traditional classifiers (global thresholding, local adaptive thresholding, and hierarchical classification). Next, classification performance as a function of the diameter of the remaining lumen (0.5 to 1.5 mm) in the partially-occluded artery was tested using both simulated (60 test images at each of 7 diameters) and experimental data sets. Experimental test data sets were acquired in four 3D-printed phantoms from human anatomy and six ex vivo porcine arteries. Accuracy of classifying the path through the artery was evaluated using microcomputed tomography of phantoms and ex vivo arteries as a ground truth for comparison. RESULTS An aperture size of 3.8 mm resulted in the best-performing classification based on sensitivity and Jaccard index, with a significant increase in Jaccard index (p < 0.05) as aperture diameter increased. In comparing the performance of the supervised classifier and traditional classification strategies with simulated test data, sensitivity and F1 score for U-net were 0.95 ± 0.02 and 0.96 ± 0.01, respectively, compared to 0.83 ± 0.03 and 0.41 ± 0.13 for the best-performing conventional approach, hierarchical classification. In simulated test images, sensitivity (p < 0.05) and Jaccard index both increased with increasing artery diameter (p < 0.05). Classification of images acquired in artery phantoms with remaining lumen diameters ≥ 0.75 mm resulted in accuracies > 90%, while mean accuracy decreased to 82% when artery diameter decreased to 0.5 mm. For testing in ex vivo arteries, average binary accuracy, F1 score, Jaccard index, and sensitivity each exceeded 0.9. CONCLUSIONS Segmentation of ultrasound images of partially-occluded peripheral arteries acquired with a forward-viewing, robotically-steered guidewire system was demonstrated for the first-time using representation learning. This could represent a fast, accurate approach for guiding peripheral revascularization.
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Affiliation(s)
- Graham C. Collins
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA, 30309
| | - Stephan Strassle Rojas
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 30309
| | - Zachary L. Bercu
- Interventional Radiology, Emory University School of Medicine, Atlanta, GA, USA, 30308
| | - Jaydev P. Desai
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA, 30309
| | - Brooks D. Lindsey
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA, 30309
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 30309
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Tang Y, Tsumura R, Kaminski JT, Zhang HK. Actuated Reflector-Based 3-D Ultrasound Imaging With Synthetic Aperture Focusing. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:2437-2446. [PMID: 35675232 PMCID: PMC9339534 DOI: 10.1109/tuffc.2022.3180980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The 3-D ultrasound (US) imaging addresses the limitation in field-of-view (FOV) in conventional 2-D US imaging by providing 3-D viewing of the anatomy. The 3-D US imaging has been extensively adapted for diagnosis and image-guided surgical intervention. However, conventional approaches to implement 3-D US imaging require either expensive and sophisticated 2-D array transducers or external actuation mechanisms to move a 1-D array mechanically. Here, we propose a 3-D US imaging mechanism using an actuated acoustic reflector instead of the sensor elements for volume acquisition with significantly extended 3-D FOV, which can be implemented with simple hardware and compact size. To improve image quality on the elevation plane, we implemented the synthetic aperture focusing (SAF) method according to the diagonal geometry of the virtual element array in the proposed imaging mechanism for elevation beamforming. We first evaluated the proposed imaging mechanism and SAF with simulated point targets and cyst targets. The results of point targets suggested improved image quality on the elevation plane, and the results of cysts targets demonstrated a potential to improve 3-D visualization of human anatomy. We built a prototype imaging system with a 3-D FOV of 38 mm (lateral) by 38 mm (elevation) by 50 mm (axial) and collected data in imaging experiments with phantoms. Experimental data showed consistency with simulation results. The SAF method enhanced quantifying the cyst volume size in the breast mimicking phantom compared with no elevation beamforming. These results suggested that the proposed 3-D US imaging mechanism could potentially be applied in clinical scenarios.
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Xu K, Jiang B, Moghekar A, Kazanzides P, Boctor E. AutoInFocus, a new paradigm for ultrasound-guided spine intervention: a multi-platform validation study. Int J Comput Assist Radiol Surg 2022; 17:911-920. [PMID: 35334043 DOI: 10.1007/s11548-022-02583-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/23/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE Ultrasound-guided spine interventions often suffer from the insufficient visualization of key anatomical structures due to the complex shapes of the self-shadowing vertebrae. Therefore, we propose an ultrasound imaging paradigm, AutoInFocus (automatic insonification optimization with controlled ultrasound), to improve the key structure visibility. METHODS A phased-array probe is used in conjunction with a motion platform to image a controlled workspace, and the resulting images from multiple insonification angles are combined to reveal the target anatomy. This idea is first evaluated in simulation and then realized as a robotic platform and a miniaturized patch device. A spine phantom (CIRS) and its CT scan were used in the evaluation experiments to quantitatively and qualitatively analyze the advantages of the proposed method over the traditional approach. RESULTS We showed in simulation that the proposed system setup increased the visibility of interspinous space boundary, a key feature for lumbar puncture guidance, from 44.13 to 67.73% on average, and the 3D spine surface coverage from 14.31 to 35.87%, compared to traditional imaging setup. We also demonstrated the feasibility of both robotic and patch-based realizations in a spine phantom study. CONCLUSION This work lays the foundation for a new imaging paradigm that leverages redundant and controlled insonification to allow for imaging optimization of the complex vertebrae anatomy, making it possible for high-quality visualization of key anatomies during ultrasound-guided spine interventions.
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Affiliation(s)
- Keshuai Xu
- Department of Computer Science, Johns Hopkins University, Baltimore, 21218, MD, USA
| | - Baichuan Jiang
- Department of Computer Science, Johns Hopkins University, Baltimore, 21218, MD, USA
| | - Abhay Moghekar
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, 21205, MD, USA
| | - Peter Kazanzides
- Department of Computer Science, Johns Hopkins University, Baltimore, 21218, MD, USA
| | - Emad Boctor
- Department of Computer Science, Johns Hopkins University, Baltimore, 21218, MD, USA.
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Collins GC, Brumfiel TA, Bercu ZL, Desai JP, Lindsey BD. Dual-Resonance (16/32 MHz) Piezoelectric Transducer With a Single Electrical Connection for Forward-Viewing Robotic Guidewire. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:1428-1441. [PMID: 35143395 PMCID: PMC9013008 DOI: 10.1109/tuffc.2022.3150746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Peripheral artery disease (PAD) affects more than 200 million people globally. Minimally invasive endovascular procedures can provide relief and salvage limbs while reducing injury rates and recovery times. Unfortunately, when a calcified chronic total occlusion is encountered, ~25% of endovascular procedures fail due to the inability to advance a guidewire using the view provided by fluoroscopy. To enable a sub-millimeter, robotically steerable guidewire to cross these occlusions, a novel single-element, dual-band transducer is developed that provides simultaneous multifrequency, forward-viewing imaging with high penetration depth and high spatial resolution while requiring only a single electrical connection. The design, fabrication, and acoustic characterization of this device are described, and proof-of-concept imaging is demonstrated in an ex vivo porcine artery after integration with a robotically steered guidewire. Measured center frequencies of the developed transducer were 16 and 32 MHz, with -6 dB fractional bandwidths of 73% and 23%, respectively. When imaging a 0.2-mm wire target at a depth of 5 mm, measured -6 dB target widths were 0.498 ± 0.02 and 0.268 ± 0.01 mm for images formed at 16 and 32 MHz, respectively. Measured SNR values were 33.3 and 21.3 dB, respectively. The 3-D images of the ex vivo artery demonstrate high penetration for visualizing vessel morphology at 16 MHz and ability to resolve small features close to the transducer at 32 MHz. Using images acquired simultaneously at both frequencies as part of an integrated forward-viewing, guidewire-based imaging system, an interventionalist could visualize the best path for advancing the guidewire to improve outcomes for patients with PAD.
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Collins GC, Sarma A, Bercu ZL, Desai JP, Lindsey BD. A Robotically Steerable Guidewire With Forward-Viewing Ultrasound: Development of Technology for Minimally-Invasive Imaging. IEEE Trans Biomed Eng 2021; 68:2222-2232. [PMID: 33264091 PMCID: PMC8279262 DOI: 10.1109/tbme.2020.3042115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE The current standard of care for peripheral chronic total occlusions involves the manual routing of a guidewire under fluoroscopy. Despite significant improvements in recent decades, navigation remains clinically challenging with high rates of procedural failure and iatrogenic injury. To address this challenge, we present a proof-of-concept robotic guidewire system with forward-viewing ultrasound imaging to allow visualization and maneuverability through complex vasculature. METHODS A 0.035" guidewire-specific ultrasound transducer with matching layer and acoustic backing was designed, fabricated, and characterized. The effect of guidewire motion on signal decorrelation was assessed with simulations and experimentally, driving the development of a synthetic aperture beamforming approach to form images as the transducer is steered on the robotic guidewire. System performance was evaluated by imaging wire targets in water. Finally, proof-of-concept was demonstrated by imaging an ex vivo artery. RESULTS The designed custom transducer was fabricated with a center frequency of 15.7 MHz, 45.4% fractional bandwidth, and 31 dB SNR. In imaging 20 μm wire targets at a depth of 6 mm, the lateral -6 dB target width was 0.25 ± 0.03 mm. The 3D artery reconstruction allowed visualization of vessel wall structure and lumen. CONCLUSION Initial proof-of-concept for an ultrasound transducer-tipped steerable guidewire including 3D image formation without an additional sensor to determine guidewire position was demonstrated for a sub-mm system with an integrated ultrasound transducer and a robotically-steered guidewire. SIGNIFICANCE The developed forward-viewing, robotically-steered guidewire may enable navigation through occluded vascular regions that cannot be crossed with current methods.
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Bratu E, Dwyer R, Noble J. A Graph-Based Method for Optimal Active Electrode Selection in Cochlear Implants. MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION : MICCAI ... INTERNATIONAL CONFERENCE ON MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION 2020; 12263:34-43. [PMID: 33884379 DOI: 10.1007/978-3-030-59716-0_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The cochlear implant (CI) is a neural prosthetic that is the standard-of-care treatment for severe-to-profound hearing loss. CIs consist of an electrode array inserted into the cochlea that electrically stimulates auditory nerve fibers to induce the sensation of hearing. Competing stimuli occur when multiple electrodes stimulate the same neural pathways. This is known to negatively impact hearing outcomes. Previous research has shown that image-processing techniques can be used to analyze the CI position in CT scans to estimate the degree of competition between electrodes based on the CI user's unique anatomy and electrode placement. The resulting data permits an algorithm or expert to select a subset of electrodes to keep active to alleviate competition. Expert selection of electrodes using this data has been shown in clinical studies to lead to significantly improved hearing outcomes for CI users. Currently, we aim to translate these techniques to a system designed for worldwide clinical use, which mandates that the selection of active electrodes be automated by robust algorithms. Previously proposed techniques produce optimal plans with only 48% success rate. In this work, we propose a new graph-based approach. We design a graph with nodes that represent electrodes and edge weights that encode competition between electrode pairs. We then find an optimal path through this graph to determine the active electrode set. Our method produces results judged by an expert to be optimal in over 95% of cases. This technique could facilitate widespread clinical translation of image-guided cochlear implant programming methods.
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Affiliation(s)
- Erin Bratu
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA
| | - Robert Dwyer
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jack Noble
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235, USA
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