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Ultrasonic Imaging

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https://www.readbyqxmd.com/read/30417745/on-factors-affecting-subharmonic-aided-pressure-estimation-shape
#1
Ipshita Gupta, John R Eisenbrey, Priscilla Machado, Maria Stanczak, Kirk Wallace, Flemming Forsberg
Subharmonic-aided pressure estimation (SHAPE) estimates hydrostatic pressure using the inverse relationship with subharmonic amplitude variations of ultrasound contrast agents (UCAs). We studied the impact of varying incident acoustic outputs (IAO), UCA concentration, and hematocrit on SHAPE. A Logiq 9 scanner with a 4C curvilinear probe (GE, Milwaukee, Wisconsin) was used with Sonazoid (GE Healthcare, Oslo, Norway) transmitting at 2.5 MHz and receiving at 1.25 MHz. An improved IAO selection algorithm provided improved correlations ( r from -0...
November 12, 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30239291/on-the-feasibility-of-ultrasound-imaging-enrichment-by-medium-temperature-changes
#2
C A Teixeira, M Pastrana-Chalco, R J Simões, A Pedrosa, M A von Krüger, A V Alvarenga, A J Fontes-Pereira, W C A Pereira
We describe the concept of a new imaging modality based on the tracking and dynamic modeling of local intensity changes (ICs) observed in conventional ultrasound images collected during a medium-temperature change. We computed the pixel-by-pixel IC from averaged B-mode images that exhibited different behaviors with varying temperature resulting from changes in the speed of sound, which consequently induce changes in the backscattered energy. Moreover, for each pixel, a first-order polynomial model was adjusted to the different temperature-dependent ICs...
September 21, 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30222052/a-locally-adaptive-phase-aberration-correction-lapac-method-for-synthetic-aperture-sequences
#3
Gustavo Chau, Marko Jakovljevic, Roberto Lavarello, Jeremy Dahl
Phase aberration is a phenomenon caused by heterogeneity of the speed of sound in tissue, in which the actual speed of sound of the tissue is different than the assumed speed of sound used for beamforming. It reduces the quality and resolution of ultrasonic images and impairs clinical diagnostic capabilities. Although phase aberration correction (PAC) methods can reduce these detrimental effects, most practical implementations of PAC methods are based on the near field phase screen model, which have limited ability to represent the true aberration induced by inhomogeneous tissue...
September 15, 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30203724/robust-waveform-design-of-ultrasound-arrays-for-medical-imaging
#4
Amir Gholampour, Sayed Mahmoud Sakhaei, Seyed Mehdi Hosseini Andargoli
Sound speed is an effective parameter in designing an optimal beamformer. In conventional ultrasound imaging systems, the beamformer is designed assuming a fixed value of speed, whereas the speed in a tissue is not known precisely and also may fluctuate by a great value. The errors in estimating sound speed may lead to a severe degradation in the reconstructed image, as mainlobe width and sidelobe level of the beampattern are sensitive to the speed variations. In this paper, we consider the design of a transmit beamformer, which is robust to the speed variations...
November 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30182816/group-versus-phase-velocity-of-shear-waves-in-soft-tissues
#5
Kevin J Parker, Juvenal Ormachea, Zaegyoo Hah
Across the varieties of waves that have been studied in physics, it is well established that group velocities can be significantly greater than or less than phase velocities measured within comparable frequency bands, depending on the particular mechanisms involved. The distinction between group and phase velocities is important in elastography, because diagnoses are made based on shear wave speed estimations from a variety of techniques. We review the general definitions of group and phase velocity and examine their specific relations within an important general class of rheological models...
November 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30101677/evaluation-of-the-effect-of-tissue-compression-on-the-results-of-shear-wave-elastography-measurements
#6
Jaromir Vachutka, Zuzana Sedlackova, Tomas Furst, Miroslav Herman, Jan Herman, Richard Salzman, Ladislav Dolezal
Shear wave imaging is considered to be more precise and less operator dependent when compared with strain imaging. It enables quantitative and reproducible data (Young's modulus of the imaged tissue). However, results of shear wave imaging can be affected by a variety of different factors. The aim of this study is to evaluate the effect of the pressure applied by the ultrasound probe during examination on the measured values of Young's modulus. The effect of the tissue compression on the results of the real-time shear wave elastography was evaluated via the gelatine phantom measurements, via the ex vivo experiments with pig liver, and via the in vivo measurements of the thyroid gland stiffness on healthy volunteers...
November 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/30015593/preliminary-study-of-chronic-liver-classification-on-ultrasound-images-using-an-ensemble-model
#7
Puja Bharti, Deepti Mittal, Rupa Ananthasivan
Chronic liver diseases are fifth leading cause of fatality in developing countries. Their early diagnosis is extremely important for timely treatment and salvage life. To examine abnormalities of liver, ultrasound imaging is the most frequently used modality. However, the visual differentiation between chronic liver and cirrhosis, and presence of heptocellular carcinomas (HCC) evolved over cirrhotic liver is difficult, as they appear almost similar in ultrasound images. In this paper, to deal with this difficult visualization problem, a method has been developed for classifying four liver stages, that is, normal, chronic, cirrhosis, and HCC evolved over cirrhosis...
November 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29923458/a-novel-microflow-phantom-dedicated-to-ultrasound-microvascular-measurements
#8
Virginie Grand-Perret, Jean-René Jacquet, Ingrid Leguerney, Baya Benatsou, Jean-Marc Grégoire, Georges Willoquet, Ayache Bouakaz, Nathalie Lassau, Stephanie Pitre-Champagnat
Tumor microvascularization is a biomarker of response to antiangiogenic treatments and is accurately assessed by ultrasound imaging. Imaging modes used to visualize slow flows include Power Doppler imaging, dynamic contrast-enhanced ultrasonography, and more recently, microvascular Doppler. Flow phantoms are used to evaluate the performance of Doppler imaging techniques, but they do not have a steady flow and sufficiently small channels. We report a novel device for robust and stable microflow measurements and the study of the microvascularization...
September 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29857786/ultrasonic-nakagami-imaging-of-high-intensity-focused-ultrasound-induced-thermal-lesions-in-porcine-livers-ex-vivo-study
#9
Sheng-Min Huang, Hao-Li Liu, Dai-Wei Li, Meng-Lin Li
High-intensity focused ultrasound (HIFU) has demonstrated the capacity to be used for local thermal ablation in clinical surgery; however, relying solely on conventional ultrasound B-mode imaging to monitor HIFU thermal ablation and determine ablation levels remains a challenge. Here, we experimentally demonstrate the ability to use Nakagami imaging to monitor HIFU-induced thermal lesions in porcine livers ex vivo. Ultrasonic Nakagami imaging has been proven to be able to characterize tissues with different scatterer concentrations and distributions...
September 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29848216/method-for-recovering-lost-ultrasonic-information-using-the-echo-intensity-mean
#10
Sara Bahramian, Craig K Abbey, Michael F Insana
The axial resolution of a B-mode (or intensity) image is limited by the bandwidth of the pulse envelope. In this report, we investigate the source of this limitation by examining the transfer of high-resolution information from the tissue impedance variance throughout the imaging process. For that purpose, we express the mean and variance of the echo-intensity signal as a linear system to track the flow of object information along the image-formation chain. The results reveal how demodulation influences the available information by discarding high spatial-frequency information...
September 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29848202/is-kidney-stiffness-measured-using-elastography-influenced-mainly-by-vascular-factors-in-patients-with-diabetic-kidney-disease
#11
Flaviu Bob, Iulia Grosu, Ioan Sporea, Romulus Timar, Daniel Lighezan, Alina Popescu, Roxana Sirli, Roxana Buzas, Ligia Petrica, Mircea Munteanu, Adalbert Schiller
Studies published so far using ultrasound-based elastography in the kidneys, lack to prove a clear relationship between kidney shear wave speed (KSWS) and renal disease progression. Taking into account that the kidney is a highly vascularized organ, the present study aims to find a relationship between KSWS and vascular factors (blood pressure [BP], arterial stiffness). Our study included 38 diabetic kidney disease patients (mean age 56.52 ± 16.12 years, 19 female, 19 male). KSWS, an indicator of renal stiffness, was measured using point Shear Wave Elastography (pSWE; Siemens Acuson S2000)...
September 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29862931/automated-identification-and-localization-of-the-inferior-vena-cava-using-ultrasound-an-animal-study
#12
Jiangang Chen, Jiawei Li, Xin Ding, Cai Chang, Xiaoting Wang, Dean Ta
Ultrasound measurement of the inferior vena cava (IVC) is widely implemented in the clinic. However, the process is time consuming and labor intensive, because the IVC diameter is continuously changing with respiration. In addition, artificial errors and intra-operator variations are always considerable, making the measurement inconsistent. Research efforts were recently devoted to developing semiautomated methods. But most required an initial identification of the IVC manually. As a first step toward fully automated IVC measurement, in this paper, we present an intelligent technique for automated IVC identification and localization...
July 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29862930/uitc-abstracts-2018
#13
(no author information available yet)
No abstract text is available yet for this article.
July 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29739309/performance-evaluation-of-adaptive-imaging-based-on-multiphase-apodization-with-cross-correlation-a-pilot-study-in-abdominal-ultrasound
#14
Junseob Shin, Yu Chen, Harshawn Malhi, Frank Chen, Jesse Yen
Degradation of image contrast caused by phase aberration, off-axis clutter, and reverberation clutter remains one of the most important problems in abdominal ultrasound imaging. Multiphase apodization with cross-correlation (MPAX) is a novel beamforming technique that enhances ultrasound image contrast by adaptively suppressing unwanted acoustic clutter. MPAX employs multiple pairs of complementary sinusoidal phase apodizations to intentionally introduce grating lobes that can be used to derive a weighting matrix, which mostly preserves the on-axis signals from tissue but reduces acoustic clutter contributions when multiplied with the beamformed radio-frequency (RF) signals...
July 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29683052/effect-of-transmit-beamforming-on-clutter-levels-in-transthoracic-echocardiography
#15
Vaibhav Kakkad, Melissa LeFevre, Kingshuk Roy Choudhury, Joseph Kisslo, Gregg E Trahey
Transmit beamforming has a strong impact on several factors that govern image quality, field-of-view, and frame-rate in ultrasound imaging. For cardiac applications, the visualization of fine structures and the ability to track their motion is equally important. Consequently, beamforming choices for echocardiography aim to optimize these trade-offs. Acoustic clutter can dramatically impact image quality and degrade the diagnostic value of cardiac ultrasound imaging. Clutter levels, however, are closely tied to the choice of beamforming configuration...
July 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29506441/three-dimensional-visualization-of-ultrasound-backscatter-statistics-by-window-modulated-compounding-nakagami-imaging
#16
Zhuhuang Zhou, Shuicai Wu, Man-Yen Lin, Jui Fang, Hao-Li Liu, Po-Hsiang Tsui
In this study, the window-modulated compounding (WMC) technique was integrated into three-dimensional (3D) ultrasound Nakagami imaging for improving the spatial visualization of backscatter statistics. A 3D WMC Nakagami image was produced by summing and averaging a number of 3D Nakagami images (number of frames denoted as N) formed using sliding cubes with varying side lengths ranging from 1 to N times the transducer pulse. To evaluate the performance of the proposed 3D WMC Nakagami imaging method, agar phantoms with scatterer concentrations ranging from 2 to 64 scatterers/mm3 were made, and six stages of fatty liver (zero, one, two, four, six, and eight weeks) were induced in rats by methionine-choline-deficient diets (three rats for each stage, total n = 18)...
May 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29353529/ultrasound-shear-wave-elastography-of-the-normal-prostate-interobserver-reproducibility-and-comparison-with-functional-magnetic-resonance-tissue-characteristics
#17
Hugh Harvey, Veronica Morgan, Jeremie Fromageau, Tuathan O'Shea, Jeffrey Bamber, Nandita M deSouza
The purpose of this study was to establish interobserver reproducibility of Young's modulus (YM) derived from ultrasound shear wave elastography (US-SWE) in the normal prostate and correlate it with multiparametric magnetic resonance imaging (mpMRI) tissue characteristics. Twenty men being screened for prostate cancer underwent same-day US-SWE (10 done by two blinded, newly-trained observers) and mpMRI followed by 12-core biopsy. Bland-Altman plots established limits of agreement for YM. Quantitative data from the peripheral zone (PZ) and the transitional zone (TZ) for YM, apparent diffusion coefficient (ADC, mm2 /s from diffusion-weighted MRI), and Ktrans (volume transfer coefficient, min-1 ), Ve (extravascular-extracellular space, %), Kep (rate constant, /min), and initial area under the gadolinium concentration curve (IAUGC60, mmol/L/s) from dynamic contrast-enhanced MRI were obtained for slice-matched prostate sextants...
May 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29332489/thermoacoustic-lensing-in-ultrasound-imaging-of-nonechogenic-tissue-during-high-intensity-focused-ultrasound-exposure
#18
Matthew Jahns, Dan MacDougall, Robert B A Adamson
We develop a ray-tracing theory to describe the effects of thermoacoustic lensing during high-intensity focused ultrasound (HIFU) on ultrasound images of reflectors lying distal to the HIFU focal region and discuss the application of thermal lensing effects to dose monitoring in HIFU therapy. By analyzing the effects of thermal and geometric delays of acoustic rays passing through a region of tissue undergoing localized heating, we show how the shape of a reflector distal to the heated region can be predicted and present experimental measurements in good agreement with the model...
May 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29207924/speckle-tracking-in-transcranial-ultrasound-allows-noninvasive-analysis-of-pulsation-patterns-of-the-third-ventricle
#19
Benjamin Würzer, Cristina Laza, Jörn Pons-Kühnemann, Manfred Kaps, Bernd Junge, Florian C Roessler
Cerebrospinal fluid (CSF) flow is sensitive to many cerebral disorders. We aimed to develop a noninvasive bedside method to detect physiological and pathological CSF phenomena by measuring pulsation patterns of the third ventricle. By transcranial B-mode ultrasound, electrocardiography (ECG)-gated video loops of the third ventricle were acquired. "Speckle tracking" software was used to quantify the relative change of its width. We conducted measurements of nine cardiac cycles in 11 healthy subjects in sitting and in supine position during Valsalva maneuver to investigate the influence of an increased intracranial pressure on the relative deformation of the third ventricle...
March 2018: Ultrasonic Imaging
https://www.readbyqxmd.com/read/29182056/lesion-segmentation-in-automated-3d-breast-ultrasound-volumetric-analysis
#20
Richa Agarwal, Oliver Diaz, Xavier Lladó, Albert Gubern-Mérida, Joan C Vilanova, Robert Martí
Mammography is the gold standard screening technique in breast cancer, but it has some limitations for women with dense breasts. In such cases, sonography is usually recommended as an additional imaging technique. A traditional sonogram produces a two-dimensional (2D) visualization of the breast and is highly operator dependent. Automated breast ultrasound (ABUS) has also been proposed to produce a full 3D scan of the breast automatically with reduced operator dependency, facilitating double reading and comparison with past exams...
March 2018: Ultrasonic Imaging
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