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https://www.readbyqxmd.com/read/28645795/high-frame-rate-power-doppler-ultrasound-is-more-sensitive-than-conventional-power-doppler-in-detecting-rheumatic-vascularisation
#1
Myrthe van der Ven, Jolanda J Luime, Levinia L van der Velden, Johan G Bosch, Johanna M W Hazes, Hendrik J Vos
Early recognition of joint inflammation will increase treatment efficacy in rheumatoid arthritis (RA). Yet, conventional power Doppler (PD) ultrasound might not be sufficiently sensitive to detect minor inflammation. We investigated the sensitivity of high-frame rate Doppler, combined with singular value decomposition technique, to suppress tissue signals, for microvascular flow in a flow phantom setup and in a proof-of-principle study in healthy controls and in RA patients with different disease activities...
June 20, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28644804/global-time-delay-estimation-in-ultrasound-elastography
#2
Hoda S Hashemi, Hassan Rivaz
A critical step in quasi-static ultrasound elastography is estimation of time-delay between two frames of radiofrequency (RF) data that are obtained while the tissue is undergoing deformation. This paper presents a novel technique for timedelay estimation (TDE) of all samples of RF data simultaneously, thereby exploiting all the information in RF data for TDE. A nonlinear cost function that incorporates similarity of RF data intensity and prior information of displacement continuity is formulated. Optimization of this function involves searching for TDE of all samples of the RF data, rendering the optimization intractable with conventional techniques given that the number of variables can be approximately one million...
June 21, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28643383/multiecho-pseudo-golden-angle-stack-of-stars-thermometry-with-high-spatial-and-temporal-resolution-using-k-space-weighted-image-contrast
#3
Bryant T Svedin, Allison Payne, Bradley D Bolster, Dennis L Parker
PURPOSE: Implement and evaluate a 3D MRI method to measure temperature changes with high spatial and temporal resolution and large field of view. METHODS: A multiecho pseudo-golden angle stack-of-stars (SOS) sequence with k-space weighted image contrast (KWIC) reconstruction was implemented to simultaneously measure multiple quantities, including temperature, initial signal magnitude M(0), transverse relaxation time ( T2*), and water/fat images. Respiration artifacts were corrected using self-navigation...
June 22, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28642054/development-of-a-tailored-thyroid-gland-phantom-for-fine-needle-aspiration-cytology-by-three-dimensional-printing
#4
Masayuki Baba, Keitaro Matsumoto, Naoya Yamasaki, Hisakazu Shindo, Hiroshi Yano, Megumi Matsumoto, Ryota Otsubo, Murray John Lawn, Naoto Matsuo, Ikuo Yamamoto, Shigekazu Hidaka, Takeshi Nagayasu
BACKGROUND: Fine-needle aspiration cytology (FNAC) is a challenging and risky procedure for inexperienced clinicians to perform because of the proximity of the thyroid to the jugular veins, carotid arteries, and trachea. A phantom model for transfixion practice would help train clinicians in FNAC. OBJECTIVE: To fabricate a tailored phantom with consideration for authenticity of size, touch, feel, and ultrasonographic (US) characteristics. METHODS: A three-dimensional (3D) digital model of the human neck was reconstructed from computed tomography data of a subject...
June 19, 2017: Journal of Surgical Education
https://www.readbyqxmd.com/read/28641910/dependence-of-boiling-histotripsy-treatment-efficiency-on-hifu-frequency-and-focal-pressure-levels
#5
Tatiana D Khokhlova, Yasser A Haider, Adam D Maxwell, Wayne Kreider, Michael R Bailey, Vera A Khokhlova
Boiling histotripsy (BH) is a high-intensity focused ultrasound (HIFU)-based method of mechanical tissue fractionation that utilizes millisecond-long bursts of HIFU shock waves to cause boiling at the focus in milliseconds. The subsequent interaction of the incoming shocks with the vapor bubble mechanically lyses surrounding tissue and cells. The acoustic parameter space for BH has been investigated previously and an inverse dependence between the HIFU frequency and the dimensions of a BH lesion has been observed...
June 19, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28638983/treatment-of-benign-thyroid-nodules-by-high-intensity-focused-ultrasound-hifu-at-different-acoustic-powers-a-study-on-in-silico-phantom
#6
Fabiano Bini, Pierpaolo Trimboli, Franco Marinozzi, Luca Giovanella
BACKGROUND: The non-surgical therapies of benign thyroid nodules are gaining momentum due to the possibility to reduce the nodule's volume and avoid surgery. As the last technique introduced, high intensity focused ultrasound allows the thermal tissue treatment by directing energy inside the targeted nodule with no invasive instruments. In the present study we applied the Food and Drug Administration high intensity focused ultrasound simulator to in-silico phantom to evaluate the effects obtained by different acoustic powers...
June 21, 2017: Endocrine
https://www.readbyqxmd.com/read/28634641/a-novel-technique-for-ultrasound-guided-central-venous-catheterization-under-short-axis-out-of-plane-approach-stepwise-flashing-with-triangulation
#7
Toshinori Horiuchi, Chie Okuda, Naoko Kurita, Ayako Yamaguchi, Kazuhiko Kitagawa, Masafumi Takeda, Keiichi Sha, Toshihiro Nagahata
In ultrasound-guided central venous catheterization, there is no standard technique either for the needle tip visualization or for the adequate needle angle and entry to the skin with short-axis view under out-of-plane technique. In the present study, we propose a novel technique named "stepwise flashing with triangulation", and the efficacy of this technique is assessed. Before and after a didactic session in which the technique was explained, 12 novice residents were asked to position the needle tip on or into the imitation vessels and to avoid deeper penetration by using an agar tissue phantom with ultrasound guidance...
June 20, 2017: Journal of Anesthesia
https://www.readbyqxmd.com/read/28631853/high-sensitivity-mr-acoustic-radiation-force-imaging-using-transition-band-balanced-steady-state-free-precession
#8
Yuan Zheng, Michael Marx, G Wilson Miller, Kim Butts Pauly
PURPOSE: MR acoustic radiation force imaging (MR-ARFI) provides a method to visualize the focal spot of a focused ultrasound (FUS) beam without introducing a significant temperature rise. With conventional spoiled MR-ARFI pulse sequences, the ARFI phase always equals the motion-encoded phase. In this work, MR-ARFI using transition band balanced steady-state free precession (bSSFP) is presented, which improves the sensitivity of MR-ARFI with high acquisition speed. THEORY AND METHODS: Motion-encoding gradients (MEG) are inserted into bSSFP sequences for MR-ARFI...
June 20, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28626903/economical-sponge-phantom-for-teaching-understanding-and-researching-a-and-b-line-reverberation-artifacts-in-lung-ultrasound
#9
Christian Blüthgen, Sergio Sanabria, Thomas Frauenfelder, Volker Klingmüller, Marga Rominger
This project evaluated a low-cost sponge phantom setup for its capability to teach and study A- and B-line reverberation artifacts known from lung ultrasound and to numerically simulate sound wave interaction with the phantom using a finite-difference time-domain (FDTD) model. Both A- and B-line artifacts were reproducible on B-mode ultrasound imaging as well as in the FDTD-based simulation. The phantom was found to be an easy-to-set up and economical tool for understanding, teaching, and researching A- and B-line artifacts occurring in lung ultrasound...
June 19, 2017: Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine
https://www.readbyqxmd.com/read/28622670/adaptive-clutter-demodulation-for-non-contrast-ultrasound-perfusion-imaging
#10
Jaime Tierney, Crystal Coolbaugh, Theodore Towse, Brett Byram
Conventional Doppler ultrasound is useful for visualizing fast blood flow in large resolvable vessels. However, frame rate and tissue clutter caused by movement of the patient or sonographer make visualizing slow flow with ultrasound difficult. Patient and sonographer motion causes spectral broadening of the clutter signal, which limits ultrasound's sensitivity to velocities greater than 5-10mm/s for typical clinical imaging frequencies. To address this, we propose a clutter filtering technique that may increase the sensitivity of Doppler measurements to at least as low as 0...
June 13, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28618301/noninvasive-measurement-of-wave-speed-of-porcine-cornea-in-ex-vivo-porcine-eyes-for-various-intraocular-pressures
#11
Boran Zhou, Arthur J Sit, Xiaoming Zhang
The objective of this study was to extend an ultrasound surface wave elastography (USWE) technique for noninvasive measurement of ocular tissue elastic properties. In particular, we aim to establish the relationship between the wave speed of cornea and the intraocular pressure (IOP). Normal ranges of IOP are between 12 and 22mmHg. Ex vivo porcine eye balls were used in this research. The porcine eye ball was supported by the gelatin phantom in a testing container. Some water was pour into the container for the ultrasound measurement...
June 7, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28618069/optimization-of-acoustic-radiation-force-imaging-influence-of-timing-parameters-on-sensitivity
#12
Tetiana Dadakova, Axel Joachim Krafft, Ali Caglar Özen, Michael Bock
PURPOSE: Optimization of timing parameters for MR-guided ARFI to achieve the highest displacement signal-to-noise ratio (SNRd ). THEORY AND METHODS: In MR-guided ARFI the phase change induced by motion encoding gradients (MEGs) is measured to assess tissue displacement. The sensitivity of this encoding procedure depends on several timing parameters, such as the MEG duration and the offset time between ultrasound (US) and MEG. Furthermore, mechanical and MR tissue constants and MEG schemes (bipolar or three-lobed) influence SNRd ...
June 15, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28604358/dual-stage-beamforming-in-absence-of-front-end-receive-focusing
#13
Deep Bera, Johan Bosch, Martin Verweij, Nico De Jong, Hendrik Vos
Ultrasound front-end receive designs for miniature, wireless, and/or matrix transducers might be simplified considerably by direct element summation in receive. In this paper we develop a dual-stage beamforming technique which is able to produce a high quality image from scanlines that are produced with focused transmit, and simple summation in receive (no delays). We call this Non-Delayed Sequential Beamforming (NDSB). In the first stage, low-resolution RF scanlines are formed by simple summation of element signals from a running sub-aperture...
June 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28599522/visualizing-the-movement-of-the-contact-between-vocal-folds-during-vibration-by-using-array-based-transmission-ultrasonic-glottography
#14
Bowen Jing, Pengju Chigan, Zhengtong Ge, Liang Wu, Supin Wang, Mingxi Wan
For the purpose of noninvasively visualizing the dynamics of the contact between vibrating vocal fold medial surfaces, an ultrasonic imaging method which is referred to as array-based transmission ultrasonic glottography is proposed. An array of ultrasound transducers is used to detect the ultrasound wave transmitted from one side of the vocal folds to the other side through the small-sized contact between the vocal folds. A passive acoustic mapping method is employed to visualize and locate the contact. The results of the investigation using tissue-mimicking phantoms indicate that it is feasible to use the proposed method to visualize and locate the contact between soft tissues...
May 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28598900/interleaved-mapping-of-temperature-and-longitudinal-relaxation-rate-to-monitor-drug-delivery-during-magnetic-resonance-guided-high-intensity-focused-ultrasound-induced-hyperthermia
#15
Esther Kneepkens, Edwin Heijman, Jochen Keupp, Steffen Weiss, Klaas Nicolay, Holger Grüll
OBJECTIVES: Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a method to heat lesions noninvasively to a stable, elevated temperature and a well-suited method to induce local hyperthermia (41°C-43°C) in deep-seated tissues. Magnetic Resonance (MR) imaging provides therapy planning on anatomical images and offers temperature feedback based on near-real-time MR thermometry. Although constant acquisition of MR thermometry data is crucial to ensure prolonged hyperthermia, it limits the freedom to perform measurements of other MR parameters, which are of interest during hyperthermia treatments...
June 8, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/28595851/delineation-of-post-procedure-ablation-regions-with-electrode-displacement-elastography-with-a-comparison-to-acoustic-radiation-force-impulse-imaging
#16
Wenjun Yang, Tomy Varghese, Timothy Ziemlewicz, Marci Alexander, Meghan Lubner, James Louis Hinshaw, Shane Wells, Fred T Lee
We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average...
June 5, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28595499/thermal-diffusivity-and-perfusion-constants-from-in-vivo-mr-guided-focused-ultrasound-treatments-a-feasibility-study
#17
Christopher R Dillon, Viola Rieke, Pejman Ghanouni, Allison Payne
PURPOSE: This study investigates the feasibility of non-invasively determining thermal diffusivity (α) and the Pennes perfusion parameter (w) from preclinical and clinical magnetic resonance-guided focused ultrasound (MRgFUS) temperature data. MATERIALS AND METHODS: Pre-clinical MRgFUS experiments were performed in rabbit muscle (N = 3, 28 sonications) using three-dimensional MR thermometry. 8 sonications were made in a clinical QA phantom with two-dimensional thermometry...
June 8, 2017: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/28590938/combined-passive-acoustic-mapping-and-magnetic-resonance-thermometry-for-monitoring-phase-shift-nanoemulsion-enhanced-focused-ultrasound-therapy
#18
Calum Crake, F Can Meral, Mark Burgess, Iason Papademetriou, Nathan McDannold, Tyrone Porter
Focused ultrasound (FUS) has the potential to enable precise, image-guided noninvasive surgery for the treatment of cancer in which tumors are identified and destroyed in a single integrated procedure. However, success of the method in highly vascular organs has been limited due to heat losses to perfusion, requiring development of techniques to locally enhance energy absorption and heating. In addition, FUS procedures are conventionally monitored using MRI, which provides excellent anatomical images and can map temperature, but is not capable of capturing the full gamut of available data such as the acoustic emissions generated during this inherently acoustically-driven procedure...
June 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28585511/three-dimensional-ultrasound-elasticity-imaging-on-an-automated-breast-volume-scanning-system
#19
Yuqi Wang, Haidy G Nasief, Sarah Kohn, Andy Milkowski, Tom Clary, Stephen Barnes, Paul E Barbone, Timothy J Hall
Ultrasound elasticity imaging has demonstrated utility in breast imaging, but it is typically performed with handheld transducers and two-dimensional imaging. Two-dimensional (2D) elastography images tissue stiffness of only a plane and hence suffers from errors due to out-of-plane motion, whereas three-dimensional (3D) data acquisition and motion tracking can be used to track out-of-plane motion that is lost in 2D elastography systems. A commercially available automated breast volume scanning system that acquires 3D ultrasound data with precisely controlled elevational movement of the 1D array ultrasound transducer was employed in this study...
June 1, 2017: Ultrasonic Imaging
https://www.readbyqxmd.com/read/28576644/real-time-electromagnetic-tracking-based-treatment-platform-for-high-dose-rate-prostate-brachytherapy-clinical-workflows-and-end-to-end-validation
#20
Luc Beaulieu, Emmanuel Racine, Dae Yup Han, Eric Vigneault, I-Chow Hsu, J Adam M Cunha
PURPOSE: New technologies were integrated into a novel treatment platform combining electromagnetically (EM) tracked catheters, a 3D ultrasound (3DUS) imaging device, and a new treatment planning system to provide a real-time prostate high-dose-rate (HDR) brachytherapy treatment system. This work defines workflows for offline CT and online 3DUS planning scenarios and preclinical end-to-end validation of the platform. METHODS AND MATERIALS: The platform is composed of an EM-tracked stylet, a EM-tracked 3DUS probe, and an EM-tracked template guide, all used with the NDI Aurora field generator (NDI, Ontario, Canada)...
May 30, 2017: Brachytherapy
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