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https://www.readbyqxmd.com/read/29222602/endoscopic-ultrasound-guided-biliary-drainage-using-a-newly-designed-metal-stent-with-a-thin-delivery-system-a-preclinical-study-in-phantom-and-porcine-models
#1
Kosuke Minaga, Masayuki Kitano, Masahiro Itonaga, Hajime Imai, Takeshi Miyata, Kentaro Yamao, Takashi Tamura, Junya Nuta, Kenji Warigaya, Masatoshi Kudo
PURPOSE: This study was designed to evaluate the feasibility and safety of a newly designed self-expandable metal stent for endoscopic ultrasound-guided biliary drainage (EUS-BD) when it was delivered via three different stent delivery systems: a 7.5Fr delivery catheter with a bullet-shaped tip (7.5Fr-bullet), a 7Fr catheter with a bullet-shaped tip (7Fr-bullet), or a 7Fr catheter with a tee-shaped tip (7Fr-tee). METHODS: This experimental study utilized a porcine model of biliary dilatation involving ten pigs...
December 8, 2017: Journal of Medical Ultrasonics
https://www.readbyqxmd.com/read/29222590/technical-accuracy-of-the-integration-of-an-external-ultrasonography-system-into-a-navigation-platform-effects-of-ultrasonography-probe-registration-and-target-detection
#2
Frederic A Wanis, Lars Wessels, Marcus H T Reinges, Eberhard Uhl, Andreas Jödicke
BACKGROUND: Intraoperative navigated ultrasonography has reached clinical acceptance, while published data for the accuracy of some systems are missing. We technically quantified and optimised the accuracy of the integration of an external ultrasonography system into a BrainLab navigation system. METHODS: A high-end ultrasonography system (Elegra; Siemens, Erlangen, Germany) was linked to a navigation system (Vector Vision; BrainLab, Munich, Germany). In vitro accuracy and precision was calculated from differences between a real world target (high-precision crosshair phantom) and the ultrasonography image of this target in the navigation coordinate system...
December 8, 2017: Acta Neurochirurgica
https://www.readbyqxmd.com/read/29215150/mri-monitoring-of-focused-ultrasound-sonications-near-metallic-hardware
#3
Hans Weber, Pejman Ghanouni, Aurea Pascal-Tenorio, Kim Butts Pauly, Brian A Hargreaves
PURPOSE: To explore the temperature-induced signal change in two-dimensional multi-spectral imaging (2DMSI) for fast thermometry near metallic hardware to enable MR-guided focused ultrasound surgery (MRgFUS) in patients with implanted metallic hardware. METHOD: 2DMSI was optimized for temperature sensitivity and applied to monitor focus ultrasound surgery (FUS) sonications near metallic hardware in phantoms and ex vivo porcine muscle tissue. Further, we evaluated its temperature sensitivity for in vivo muscle in patients without metallic hardware...
December 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29197911/intra-and-inter-observer-variation-and-accuracy-using-different-shear-wave-elastography-methods-to-assess-circumscribed-objects-a-phantom-study
#4
Gregor Seliger, Katharina Chaoui, Christian Kunze, Yasmina Dridi, Klaus-Vitold Jenderka, Andreas Wienke, Michael Tchirikov
AIMS: The elastic properties of circumscribed tissues (e.g., tendons, lymph nodes, prostates, brain tumors) are of considerable clinical interest. The purpose of this study was thus to compare the Intra-/Inter-observer variation and accuracy in vitro of point shear wave elastography (pSWE) with that of 2D-SWE and to assess 2D-SWE's precision with variable ROI (vROI) incircumscribed objects. MATERIAL AND METHODS: Round targets (Elasticity QA Phantom Model 049) were examined for varying degrees of stiffness (8, 14, 45, and 80 kPa) and diameters (20/10 mm)...
November 29, 2017: Medical Ultrasonography
https://www.readbyqxmd.com/read/29195755/determination-of-acoustic-cavitation-probabilities-and-thresholds-using-a-single-focusing-transducer-to-induce-and-detect-acoustic-cavitation-events-ii-systematic-investigation-in-an-agar-material
#5
Julian Haller, Volker Wilkens
In the accompanying article (Part I), a method is described to determine acoustic cavitation probabilities in tissue-mimicking materials (TMMs) using a high-intensity focused ultrasound (HIFU) transducer for both inducing and detecting the acoustic cavitation events, and its suitability for different sonication modes like continuous wave, single pulses (with pulse lengths from microseconds to milliseconds) and repeated burst signals is discussed. In Part II, the use of the method for a systematic study of the dependence of the acoustic cavitation thresholds in 3% (by weight) agar phantoms on the temporal sonication parameters is discussed...
November 28, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29195754/determination-of-acoustic-cavitation-probabilities-and-thresholds-using-a-single-focusing-transducer-to-induce-and-detect-acoustic-cavitation-events-i-method-and-terminology
#6
Julian Haller, Volker Wilkens, Adam Shaw
A method to determine acoustic cavitation probabilities in tissue-mimicking materials (TMMs) is described that uses a high-intensity focused ultrasound (HIFU) transducer for both inducing and detecting the acoustic cavitation events. The method was evaluated by studying acoustic cavitation probabilities in agar-based TMMs with and without scatterers and for different sonication modes like continuous wave, single pulses (microseconds to milliseconds) and repeated burst signals. Acoustic cavitation thresholds (defined here as the peak rarefactional in situ pressure at which the acoustic cavitation probability reaches 50%) at a frequency of 1...
November 28, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29194290/ultrasound-identifies-broken-drainage-tube-postthyroidectomy
#7
Jiayi Xing, Jian Wang, Shanshan You, Jianchu Li
Drains are routinely used after thyroidectomy and lateral neck dissection. In rare cases, the drainage tube is broken and retained in the neck. It is difficult to identify the sonographic features of the remnant tube due to variable reasons. However, through comparative and phantom observations, we noticed the double-tract sign of the tube wall and drainage holes as the key points to solving this problem. We report such a case of the ultrasound-guided localization of a broken drainage tube that was retained in the patient...
November 29, 2017: Ultrasound Quarterly
https://www.readbyqxmd.com/read/29186007/anatomically-realistic-ultrasound-phantoms-using-gel-wax-with-3d-printed-moulds
#8
Efthymios Maneas, Wenfeng Xia, Daniil I Nikitichev, Batol Daher, Maniragav Manimaran, Rui Yen J Wong, Chia-Wei Chang, Benyamin Rahmani, Claudio Capelli, Silvia Schievano, Gaetano Burriesci, Sebastien Ourselin, Anna L David, Malcolm Finlay, Simeon J West, Tom Vercauteren, Adrien E Desjardins
Here we describe methods for creating tissue-mimicking ultrasound phantoms based on patient anatomy using a soft material called gel wax. To recreate acoustically realistic tissue properties, two additives to gel wax were considered: paraffin wax to increase acoustic attenuation, and solid glass spheres to increase backscattering. The frequency dependence of ultrasound attenuation was well described with a power law over the measured range of 3 to 10 MHz. With the addition of paraffin wax in concentrations of 0 to 8 w/w%, attenuation varied from 0...
November 29, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29182946/effect-of-pulse-duration-and-pulse-repetition-frequency-of-cavitation-histotripsy-on-erosion-at-the-surface-of-soft-material
#9
Yufeng Zhou, Xiaotong Wang
Cavitation histotripsy with the short pulse duration (PD) but high pulse repetition frequency (PRF) disintegrates the tissue at a fluid interface. However, longer PD and lower PRF are used in the other focused ultrasound applications, where the acoustic radiation force, streaming, and cavitation are different, and their effects on erosion are unknown. In this study, the erosion at the surface of phantom/ex vivo tissue and the characteristics of induced bubble cloud captured by high-speed photography, passive cavitation detection, and light transmission during histotripsy exposure at varied PDs and PRFs but the same duty cycle were compared...
November 22, 2017: Ultrasonics
https://www.readbyqxmd.com/read/29182054/a-quantitative-method-for-the-evaluation-of-spatial-resolution-in-quality-control-of-b-mode-ultrasound-images
#10
Sabina Strocchi, Francesco Larghi, Raffaele Novario
The work describes a method to quantitatively evaluate spatial resolution in B-mode quality control images as radial modulation transfer function (MTF). The method is easy to use in in-field quality assurance programs in clinical institutions, as it is fast and can be performed with the help of phantoms that are already used for routine quality control. It uses a round insert with different echogenic characteristics compared with the phantom background. The method was automated with a MATLAB® routine, which can be run in full automatic mode or with a grade of interaction by the user, as is sometimes necessary with low-quality images...
November 1, 2017: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29168072/estimates-for-the-acoustical-stimulation-and-heating-of-multiphase-biotissue
#11
T I Zohdi, R Krone
Low-intensity, unfocused, ultrasound-induced diathermy can produce undesired temperature increases at the interface of adjacent tissues within the body; particularly, at the interface of soft tissue and bone. This study provides a computational framework for predicting an upper bound on the temperature profile within a multiphase system composed of gel pad (water), tissue and bone from an input of acoustic energy, at frequencies and power levels consistent with applications of therapeutic hyperthermia. The model consists of solving a (one-dimensional) spatially discretized bioheat transfer equation via finite-difference method and updating the solution in time with a forward-Euler scheme...
November 22, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/29163660/testing-a-new-surfactant-in-a-widely-used-blood-mimic-for-ultrasound-flow-imaging
#12
Xiaowei Zhou, Peter R Hoskins
Background: A blood-mimicking fluid developed by Ramnarine et al. has been widely used in flow phantoms for ultrasound flow imaging research, and it has also been cited by IEC 61685 as a reference for making blood-mimicking fluid.However, the surfactant material Synperonic N in this blood-mimicking fluid recipe is phased out from the European market due to environmental issues. The aim of this study is to test whether Synperonic N can be substituted by biodegradable Synperonic A7 in making blood-mimicking fluid for ultrasound flow imaging research...
November 2017: Ultrasound: Journal of the British Medical Ultrasound Society
https://www.readbyqxmd.com/read/29161293/high-intensity-focused-ultrasound-ablation-around-the-tubing
#13
Jun Yang Siu, Chenhui Liu, Yufeng Zhou
High-intensity focused ultrasound (HIFU) has been emerging as an effective and noninvasive modality in cancer treatment with very promising clinical results. However, a small vessel in the focal region could be ruptured, which is an important concern for the safety of HIFU ablation. In this study, lesion formation in the polyacrylamide gel phantom embedded with different tubing (inner diameters of 0.76 mm and 3 mm) at varied flow speeds (17-339 cm/s) by HIFU ablation was photographically recorded. Produced lesions have decreased length (~30%) but slightly increased width (~6%) in comparison to that without the embedded tubing...
2017: PloS One
https://www.readbyqxmd.com/read/29158836/a-laser-activated-biocompatible-theranostic-nanoagent-for-targeted-multimodal-imaging-and-photothermal-therapy
#14
Liming Deng, Xiaojun Cai, Danli Sheng, Yang Yang, Eric M Strohm, Zhigang Wang, Haitao Ran, Dong Wang, Yuanyi Zheng, Pan Li, Tingting Shang, Yi Ling, Fengjuan Wang, Yang Sun
Multifunctional nanoparticles have been reported for cancer detection and treatment currently. However, the accurate diagnosis and efficient treatment for tumors are still not satisfied. Here we report on the development of targeted phase change multimodal polymeric nanoparticles for the imaging and treatment of HER2-positive breast cancer. METHODS: We evaluated the multimodal imaging capabilities of the prepared nanoparticles in vitro using agar-based phantoms. The targeting performance and cytotoxicity of the nanoparticles were examined in cell culture using SKBR3 (over-expressing HER2) and MDA-MB-231 (HER2 negative) cells...
2017: Theranostics
https://www.readbyqxmd.com/read/29158692/pulsed-radiofrequency-of-brachial-plexus-under-ultrasound-guidance-for-refractory-stump-pain-a-case-report
#15
Bixin Zheng, Li Song, Hui Liu
The post-amputation (pain) syndrome, including stump pain, phantom limb sensation, and phantom limb pain is common but difficult to treat. Refractory stump pain in the syndrome is an extremely challenging and troublesome clinical condition. Patients respond poorly to drugs, nerve blocks, and other effective treatments like spinal cord stimulation and surgery. Pulsed radiofrequency (PRF) technique has been shown to be effective in reducing neuropathic pain. This report describes a patient with persistent and refractory upper limb stump pain being successfully relieved with PRF of brachial plexus under ultrasound guidance after a 6-month follow-up period, suggesting that PRF may be considered as an alternative treatment for refractory stump-neuroma pain...
2017: Journal of Pain Research
https://www.readbyqxmd.com/read/29156300/attenuation-estimation-by-repeatedly-solving-the-forward-scattering-problem
#16
Natalia Ilyina, Jeroen Hermans, Erik Verboven, Koen Van Den Abeele, Emiliano D'Agostino, Jan D'hooge
Estimation of the attenuation is important in medical ultrasound not only for correct time-gain compensation but also for tissue characterization. In this paper, the feasibility of a new method for attenuation estimation is tested. The proposed method estimates the attenuation by repeatedly solving the forward wave propagation problem and matching the simulated signals to the measured ones. This approach allows avoiding common assumptions made by other methodologies and potentially allows to account and correct for other acoustic effects that may bias the attenuation estimate...
October 10, 2017: Ultrasonics
https://www.readbyqxmd.com/read/29123607/procedural-simulation-medical-student-preference-and-value-of-three-task-trainers-for-ultrasound-guided-regional-anesthesia
#17
Shadi Lahham, Taylaur Smith, Jessa Baker, Amanda Purdy, Erica Frumin, Bret Winners, Sean P Wilson, Abdulatif Gari, John C Fox
BACKGROUND: Ultrasound guided regional anesthesia is widely taught using task trainer models. Commercially available models are often used; however, they can be cost prohibitive. Therefore, alternative "homemade" models with similar fidelity are often used. We hypothesize that professional task trainers will be preferred over homemade models. The purpose of this study is to determine realism, durability and cleanliness of three different task trainers for ultrasound guided nerve blocks...
2017: World Journal of Emergency Medicine
https://www.readbyqxmd.com/read/29109632/a-manikin-based-evaluation-of-a-teaching-modality-for-ultrasound-guided-infraclavicular-longitudinal-in-plane-axillary-vein-cannulation-in-comparison-with-ultrasound-guided-internal-jugular-vein-cannulation-a-pilot-study
#18
Sanjib Adhikary, Patrick McQuillan, Michael Fortunato, David Owen, Wai-Man Liu, Venkatesan Thiruvenkatarajan
Background and Aims: Ultrasound (US)-guided infraclavicular approach for axillary vein (AXV) cannulation has gained popularity in the last decade. Material and Methods: In this manikin study, we evaluated the feasibility of a training model for teaching AXV cannulation. The learning pattern with this technique was assessed among attending anesthesiologists and residents in training. Results: A faster learning pattern was observed for AXV cannulation among the attending anesthesiologists and residents in training, irrespective of their prior experience with US...
July 2017: Journal of Anaesthesiology, Clinical Pharmacology
https://www.readbyqxmd.com/read/29107355/spatial-compounding-of-3-d-fetal-brain-ultrasound-using-probabilistic-maps
#19
Jorge Perez-Gonzalez, Fernando Arámbula-Cosío, Mario Guzmán, Lisbeth Camargo, Benjamin Gutierrez, Diana Mateus, Nassir Navab, Verónica Medina-Bañuelos
A new method to address the problem of shadowing in fetal brain ultrasound volumes is presented. The proposed approach is based on the spatial composition of multiple 3-D fetal head projections using the weighted Euclidean norm as an operator. A support vector machine, which is trained with optimal textural features, was used to assign weighting according to the posterior probabilities of brain tissue and shadows. Both phantom and real fetal head ultrasound volumes were compounded using previously reported operators and compared with the proposed composition method to validate it...
October 26, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29098986/gold-nanoparticle-nucleated-cavitation-for-enhanced-high-intensity-focused-ultrasound-therapy
#20
James R McLaughlan, David M J Cowell, Steven Freear
High intensity focused ultrasound (HIFU) or focused ultrasound surgery (FUS) is a non-invasive technique for the treatment of cancerous tissue, which is limited by difficulties in getting real-time feedback on treatment progress and long treatment durations. The formation and activity of acoustic cavitation, specifically inertial cavitation, during HIFU exposures has been demonstrated to enhance heating rates. However, without the introduction of external nuclei its formation an activity can be unpredictable, and potentially counterproductive...
November 3, 2017: Physics in Medicine and Biology
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