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https://www.readbyqxmd.com/read/28107676/characterization-of-a-new-ultrasound-device-designed-for-measuring-cortical-porosity-at-the-human-tibia-a-phantom-study
#1
M Gräsel, C-C Glüer, R Barkmann
Quantitative ultrasound (QUS) measurements of trabecular bone are a useful tool for the assessment of osteoporotic fracture risk. However, cortical bone properties (e.g. porosity) have an impact on bone strength as well and thus current research is focused on QUS assessment of cortical bone properties. Simulation studies of ultrasound propagation through cortical bone indicate that anisotropy, calculated from the ratio of the velocities in axial and tangential directions, is correlated with porosity. However, this relationship is affected by error sources, specifically bone surface curvature and variability of probe positioning...
January 4, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28106118/small-window-parametric-imaging-based-on-information-entropy-for-ultrasound-tissue-characterization
#2
Po-Hsiang Tsui, Chin-Kuo Chen, Wen-Hung Kuo, King-Jen Chang, Jui Fang, Hsiang-Yang Ma, Dean Chou
Constructing ultrasound statistical parametric images by using a sliding window is a widely adopted strategy for characterizing tissues. Deficiency in spatial resolution, the appearance of boundary artifacts, and the prerequisite data distribution limit the practicability of statistical parametric imaging. In this study, small-window entropy parametric imaging was proposed to overcome the above problems. Simulations and measurements of phantoms were executed to acquire backscattered radiofrequency (RF) signals, which were processed to explore the feasibility of small-window entropy imaging in detecting scatterer properties...
January 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28103837/evaluation-of-the-ablation-margin-of-hepatocellular-carcinoma-using-ceus-ct-mr-image-fusion-in-a-phantom-model-and-in-patients
#3
Kai Li, Zhongzhen Su, Erjiao Xu, Qiannan Huang, Qingjing Zeng, Rongqin Zheng
BACKGROUND: To assess the accuracy of contrast-enhanced ultrasound (CEUS)-CT/MR image fusion in evaluating the radiofrequency ablative margin (AM) of hepatocellular carcinoma (HCC) based on a custom-made phantom model and in HCC patients. METHODS: Twenty-four phantoms were randomly divided into a complete ablation group (n = 6) and an incomplete ablation group (n = 18). After radiofrequency ablation (RFA), the AM was evaluated using ultrasound (US)-CT image fusion, and the results were compared with the AM results that were directly measured in a gross specimen...
January 19, 2017: BMC Cancer
https://www.readbyqxmd.com/read/28095866/improvement-of-displacement-estimation-of-breast-tissue-in-ultrasound-elastography-using-the-monogenic-signal
#4
Taher Slimi, Ines Marzouk Moussa, Tarek Kraiem, Halima Mahjoubi
BACKGROUND: In breast ultrasound elastography, tissues displacements estimation is obtained through a technique that follows the evolution of tissues under stress. However, during the acquisition of B-mode images, tissue displacements are often contaminated with multiplicative noise caused by changes in the speckle pattern in the tissue. Thus, the application of monogenic signal technique on the B-mode image in order to estimate displacement tissue, result in a presence of amplified noise in the deformation tissue image, which severely obscures the useful information...
January 17, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28094067/differential-intensity-projection-for-visualisation-and-quantification-of-plaque-neovascularisation-in-contrast-enhanced-ultrasound-images-of-carotid-arteries
#5
Wing Keung Cheung, Benoy N Shah, Antonio Stanziola, Dorothy M Gujral, Navtej S Chahal, David O Cosgrove, Roxy Senior, Meng-Xing Tang
Studies have reported that intraplaque neovascularisation (IPN) is closely correlated with plaque vulnerability. In this study, a new image processing approach, differential intensity projection (DIP), was developed to visualise and quantify IPN in contrast-enhanced non-linear ultrasound image sequences of carotid arteries. DIP used the difference between the local temporal maximum and the local temporal average signals to identify bubbles against tissue non-linear artefact and noise. The total absolute and relative areas occupied by bubbles within each plaque were calculated to quantify IPN...
January 13, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28092533/linear-system-models-for-ultrasonic-imaging-intensity-signal-statistics
#6
Craig Abbey, Yang Zhu, Sara Bahramian, Michael Insana
Despite a great deal of work characterizing the statistical properties of radio-frequency backscattered ultrasound signals, less is known about the statistical properties of demodulated intensity signals. Analysis of intensity is made more difficult by a strong nonlinearity that arises in the process of demodulation. This limits our ability to characterize the spatial resolution and noise properties of B-mode ultrasound images. In this work, we generalize earlier results on two-point intensity covariance using a multivariate systems approach...
January 16, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28092532/improved-shear-wave-group-velocity-estimation-method-based-on-spatiotemporal-peak-and-thresholding-motion-search
#7
Carolina Amador Carrascal, Shigao Chen, Armando Manduca, James F Greenleaf, Matthew Urban
Quantitative ultrasound elastography is increasingly being used in the assessment of chronic liver disease. Many studies have reported ranges of liver shear wave velocities values for healthy individuals and patients with different stages of liver fibrosis. Nonetheless, ongoing efforts exist to stabilize quantitative ultrasound elastography measurements by assessing factors that influence tissue shear wave velocity values, such as food intake, body mass index (BMI), ultrasound scanners, scanning protocols, ultrasound image quality, etc...
January 11, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28092507/real-time-intravascular-ultrasound-and-photoacoustic-imaging
#8
Donald VanderLaan, Andrei B Karpiouk, Doug Yeager, Stanislav Emelianov
Combined intravascular ultrasound and intravascular photoacoustic (IVUS/IVPA) imaging is an emerging hybrid modality being explored as a means of improving the characterization of atherosclerotic plaque anatomical and compositional features. While initial demonstrations of the technique have been encouraging, they have been limited by catheter rotation and data acquisition, displaying, and processing rates on the order of several seconds per frame as well as the use of off-line image processing. Herein, we present a complete IVUS/IVPA imaging system and method capable of real-time IVUS/IVPA imaging, with online data acquisition, image processing, and display of both IVUS and IVPA images...
January 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28081004/reverberant-shear-wave-fields-and-estimation-of-tissue-properties
#9
Kevin J Parker, Juvenal Ormachea, Fernando Zvietcovich, Benjamin Castaneda
The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave behavior is assumed with a known direction of propagation. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079754/ultrasound-guided-needle-technique-accuracy-prospective-comparison-of-passive-magnetic-tracking-versus-unassisted-echogenic-needle-localization
#10
Angela N Johnson, Jeffery S Peiffer, Nahi Halmann, Luke Delaney, Cindy A Owen, Jeff Hersh
BACKGROUND AND OBJECTIVES: Ultrasound-guided regional anesthesia facilitates an approach to sensitive targets such as nerve clusters without contact or inadvertent puncture. We compared accuracy of needle placement with a novel passive magnetic ultrasound needle guidance technology (NGT) versus conventional ultrasound (CU) with echogenic needles. METHODS: Sixteen anesthesiologists and 19 residents performed a series of 16 needle insertion tasks each, 8 using NGT (n = 280) and 8 using CU (n = 280), in high-fidelity porcine phantoms...
January 11, 2017: Regional Anesthesia and Pain Medicine
https://www.readbyqxmd.com/read/28075330/building-an-open-source-simulation-platform-of-acoustic-radiation-force-based-breast-elastography
#11
Yu Wang, Bo Peng, Jingfeng Jiang
Ultrasound-based elastography techniques including quasi-static strain elastography (SE), acoustic radiation force Impulse (ARFI) imaging, point shear wave elastography (pSWE) and supersonic shear imaging (SSI) have been used to differentiate breast tumors. The objective of this study is to extend a previously published virtual simulation platform of SE toward acoustic radiation force-based breast elastography. The proposed platform inherited four key components from the previously published virtual SE platform: an ultrasound simulator (Field II), a mesh generator (Tetgen), a finite element (FE) solver (FEBio) and a visualization and data processing package (VTK)...
January 11, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28072580/in-vivo-real-time-cavitation-imaging-in-moving-organs
#12
B Arnal, J Baranger, C Demene, M Tanter, M Pernot
The stochastic nature of cavitation implies visualization of the cavitation cloud in real-time and in a discriminative manner for the safe use of focused ultrasound therapy. This visualization is sometimes possible with standard echography, but it strongly depends on the quality of the scanner, and is hindered by difficulty in discriminating from highly reflecting tissue signals in different organs. A specific approach would then permit clear validation of the cavitation position and activity. Detecting signals from a specific source with high sensitivity is a major problem in ultrasound imaging...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28072576/ultrasonic-computed-tomography-imaging-of-iron-oxide-nanoparticles
#13
Or Perlman, Haim Azhari
Iron oxide nanoparticles (IONPs) are becoming increasingly used and intensively investigated in the field of medical imaging. They are currently FDA approved for magnetic resonance imaging (MRI), and it would be highly desirable to visualize them by ultrasound as well. Previous reports using the conventional ultrasound B-scan (pulse-echo) imaging technique have shown very limited detectability of these particles. The aim of this study is to explore the feasibility of imaging IONPs using the through-transmission ultrasound methodology and demonstrate their detectability using ultrasonic computed tomography (UCT)...
February 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28070749/an-automated-microemboli-detection-and-classification-system-using-backscatter-rf-signals-and-differential-evolution
#14
Karim Ferroudji, Nabil Benoudjit, Ayache Bouakaz
Embolic phenomena, whether air or particulate emboli, can induce immediate damages like heart attack or ischemic stroke. Embolus composition (gaseous or particulate matter) is vital in predicting clinically significant complications. Embolus detection using Doppler methods have shown their limits to differentiate solid and gaseous embolus. Radio-frequency (RF) ultrasound signals backscattered by the emboli contain additional information on the embolus in comparison to the traditionally used Doppler signals...
January 9, 2017: Australasian Physical & Engineering Sciences in Medicine
https://www.readbyqxmd.com/read/28066947/training-in-eus-an-asian-perspective
#15
REVIEW
J Y Y Wong, P Kongkam, K Y Ho
Training of endoscopic ultrasound (EUS) in Asia faces two major challenges: (i) the ever-increasing demand for skills to handle a growing range of interventional EUS procedures; and (ii) a continual shortage of EUS training programs. As the therapeutic application of EUS continues to expand,(1, 2) the need to train more new endosonographers and upgrade skills of existing ones has become more critical than ever before. A formal fellowship to acquire EUS knowledge and skills in an advanced endoscopy centre has always been perceived as the best way of training novices, but such opportunities remain limited in most Asian countries...
January 9, 2017: Digestive Endoscopy: Official Journal of the Japan Gastroenterological Endoscopy Society
https://www.readbyqxmd.com/read/28057657/measuring-shear-wave-speed-with-point-shear-wave-elastography-and-mr-elastography-a-phantom-study
#16
Riwa Kishimoto, Mikio Suga, Atsuhisa Koyama, Tokuhiko Omatsu, Yasuhiko Tachibana, Daniel K Ebner, Takayuki Obata
OBJECTIVES: To compare shear-wave speed (SWS) measured by ultrasound-based point shear-wave elastography (pSWE) and MR elastography (MRE) on phantoms with a known shear modulus, and to assess method validity and variability. METHODS: 5 homogeneous phantoms of different stiffnesses were made. Shear modulus was measured by a rheometer, and this value was used as the standard. 10 SWS measurements were obtained at 4 different depths with 1.0-4.5 MHz convex (4C1) and 4...
January 5, 2017: BMJ Open
https://www.readbyqxmd.com/read/28057350/multi-slice-ultrasound-image-calibration-of-an-intelligent-skin-marker-for-soft-tissue-artefact-compensation
#17
M A Masum, M R Pickering, A J Lambert, J M Scarvell, P N Smith
In this paper, a novel multi-slice ultrasound (US) image calibration of an intelligent skin-marker used for soft tissue artefact compensation is proposed to align and orient image slices in an exact H-shaped pattern. Multi-slice calibration is complex, however, in the proposed method, a phantom based visual alignment followed by transform parameters estimation greatly reduces the complexity and provides sufficient accuracy. In this approach, the Hough Transform (HT) is used to further enhance the image features which originate from the image feature enhancing elements integrated into the physical phantom model, thus reducing feature detection uncertainty...
December 29, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28048919/su-g-jep3-05-geometry-based-transperineal-ultrasound-probe-positioning-for-image-guided-radiotherapy
#18
S Camps, F Verhaegen, P de With, D Fontanarosa
PURPOSE: The use of ultrasound (US) imaging in radiotherapy is not widespread, primarily due to the need for skilled operators performing the scans. Automation of probe positioning has the potential to remove this need and minimize operator dependence. We introduce an algorithm for obtaining a US probe position that allows good anatomical structure visualization based on clinical requirements. The first application is on 4D transperineal US images of prostate cancer patients. METHODS: The algorithm calculates the probe position and orientation using anatomical information provided by a reference CT scan, always available in radiotherapy workflows...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048861/su-g-jep1-09-evaluation-of-transperineal-ultrasound-imaging-as-a-potential-solution-for-target-tracking-during-ablative-body-radiotherapy-for-prostate-cancer
#19
M Najafi, B Han, D Cooper, S Hancock, D Hristov
PURPOSE: Prostate SABR is emerging as a clinically viable, potentially cost effective alternative to prostate IMRT but its adoption is contingent on providing solutions for accurate tracking during beam delivery. Our goal is to evaluate the performance of the Clarity Autoscan ultrasound monitoring system for inter-fractional prostate motion tracking in both phantoms and in-vivo. METHODS: In-vivo evaluation was performed under IRB protocol to allow data collection in prostate patients treated with VMAT whereby prostate was imaged through the acoustic window of the perineum...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048859/su-g-jep4-12-real-time-organ-motion-monitoring-using-ultrasound-and-kv-fluoroscopy-during-lung-sbrt-delivery
#20
E Omari, A Tai, D Cooper, M Lachaine, X Li
PURPOSE: Real-time ultrasound monitoring during SBRT is advantageous in understanding and identifying motion irregularities which may cause geometric misses. In this work, we propose to utilize real-time ultrasound to track the diaphragm in conjunction with periodical kV fluoroscopy to monitor motion of tumor or landmarks during SBRT delivery. METHODS: Transabdominal Ultrasound (TAUS) b-mode images were collected from 10 healthy volunteers using the Clarity Autoscan System (Elekta)...
June 2016: Medical Physics
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