Robust Waveform Design of Ultrasound Arrays for Medical Imaging.
Authors: Gholampour A, Sakhaei SM, Andargoli SMH Abstract 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 variat...
Source: Ultrasonic Imaging - September 13, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Group versus Phase Velocity of Shear Waves in Soft Tissues.
Authors: Parker KJ, Ormachea J, Hah Z Abstract 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...
Source: Ultrasonic Imaging - September 6, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Evaluation of the Effect of Tissue Compression on the Results of Shear Wave Elastography Measurements.
Authors: Vachutka J, Sedlackova Z, Furst T, Herman M, Herman J, Salzman R, Dolezal L Abstract 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...
Source: Ultrasonic Imaging - August 14, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Preliminary Study of Chronic Liver Classification on Ultrasound Images Using an Ensemble Model.
Authors: Bharti P, Mittal D, Ananthasivan R Abstract 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 ...
Source: Ultrasonic Imaging - July 18, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Novel Microflow Phantom Dedicated to Ultrasound Microvascular Measurements.
We report a novel device for robust and stable microflow measurements and the study of the microvascularization. Based on microfluidics technology, the prototype features wall-less cylindrical channels of diameters ranging from as small as 147 up to 436 µm, cast in a soft silicone polymer and perfused via a microfluidic flow pressure controller. The device was assessed using flow rates from 49 to 146 µL/min, with less than 1% coefficient of variation over three minutes, corresponding to velocities of 6 to 142 mm/s. This enabled us to evaluate and confirm the reliability of the Superb Microvascular Imaging Doppl...
Source: Ultrasonic Imaging - June 24, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Uitc abstracts 2018.
UITC ABSTRACTS 2018. Ultrason Imaging. 2018 Jul;40(4):245-279 Authors: PMID: 29862930 [PubMed - in process] (Source: Ultrasonic Imaging)
Source: Ultrasonic Imaging - June 7, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Automated Identification and Localization of the Inferior Vena Cava Using Ultrasound: An Animal Study.
Authors: Chen J, Li J, Ding X, Chang C, Wang X, Ta D Abstract 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 pr...
Source: Ultrasonic Imaging - June 7, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Ultrasonic Nakagami Imaging of High-intensity Focused Ultrasound-induced Thermal Lesions in Porcine Livers: Ex Vivo Study.
Authors: Huang SM, Liu HL, Li DW, Li ML Abstract 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. The pathological...
Source: Ultrasonic Imaging - June 4, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Is Kidney Stiffness Measured Using Elastography Influenced Mainly by Vascular Factors in Patients with Diabetic Kidney Disease?
Authors: Bob F, Grosu I, Sporea I, Timar R, Lighezan D, Popescu A, Sirli R, Buzas R, Petrica L, Munteanu M, Schiller A Abstract 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, a...
Source: Ultrasonic Imaging - June 1, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Method for Recovering Lost Ultrasonic Information Using the Echo-intensity Mean.
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. This analysis further points to a simple way to recover lost information with only a minor addition to signal processing. Software phantoms are used t...
Source: Ultrasonic Imaging - June 1, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Performance Evaluation of Adaptive Imaging Based on Multiphase Apodization with Cross-correlation: A Pilot Study in Abdominal Ultrasound.
Authors: Shin J, Chen Y, Malhi H, Chen F, Yen J Abstract 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 fr...
Source: Ultrasonic Imaging - May 11, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Effect of Transmit Beamforming on Clutter Levels in Transthoracic Echocardiography.
This study aims to quantify the impact of transmit beamforming on clutter levels under in vivo conditions. The performance of focused as well as plane wave transmit configurations in fundamental and harmonic modes is evaluated under matched conditions. Contrast between the cardiac chambers and the interventricular septum is used as a surrogate for the level of clutter in a given imaging scenario. Under in vivo conditions, contrast was found to improve incrementally across the four beamforming configurations in the following order: fundamental-plane, fundamental-focused, harmonic-plane, and harmonic-focused. Using the funda...
Source: Ultrasonic Imaging - April 25, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Three-dimensional Visualization of Ultrasound Backscatter Statistics by Window-modulated Compounding Nakagami Imaging.
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...
Source: Ultrasonic Imaging - March 8, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Ultrasound Shear Wave Elastography of the Normal Prostate: Interobserver Reproducibility and Comparison with Functional Magnetic Resonance Tissue Characteristics.
Authors: Harvey H, Morgan V, Fromageau J, O'Shea T, Bamber J, deSouza NM Abstract 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)...
Source: Ultrasonic Imaging - January 24, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Thermoacoustic Lensing in Ultrasound Imaging of Nonechogenic Tissue During High-intensity Focused Ultrasound Exposure.
Authors: Jahns M, MacDougall D, Adamson RBA Abstract 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 agreemen...
Source: Ultrasonic Imaging - January 17, 2018 Category: Radiology Tags: Ultrason Imaging Source Type: research

Speckle Tracking in Transcranial Ultrasound Allows Noninvasive Analysis of Pulsation Patterns of the Third Ventricle.
Authors: Würzer B, Laza C, Pons-Kühnemann J, Kaps M, Junge B, Roessler FC Abstract 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 ...
Source: Ultrasonic Imaging - December 8, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Quantitative Method for the Evaluation of Spatial Resolution in Quality Control of B-mode Ultrasound Images.
Authors: Strocchi S, Larghi F, Novario R Abstract 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 in...
Source: Ultrasonic Imaging - November 29, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Lesion Segmentation in Automated 3D Breast Ultrasound: Volumetric Analysis.
Authors: Agarwal R, Diaz O, Lladó X, Gubern-Mérida A, Vilanova JC, Martí R Abstract 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 comparis...
Source: Ultrasonic Imaging - November 29, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Analysis of Two Quantitative Ultrasound Approaches.
In this study, the relation between the LF and QUS-derived parameters is studied theoretically and experimentally on ex vivo mouse livers. As expected from the theory, LF slope is correlated to ESD ([Formula: see text]), and from experimental data, LF midband is correlated to EAC ([Formula: see text]). However, LF intercept is not correlated to ESD ([Formula: see text]) nor EAC ([Formula: see text]). The unexpected correlation observed between LF slope and EAC ([Formula: see text]) results likely from the high correlation between ESD and EAC due to the inversion process. For a liver fat percentage estimation, an important ...
Source: Ultrasonic Imaging - September 27, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

3D Tendon Strain Estimation Using High-frequency Volumetric Ultrasound Images: A Feasibility Study.
Authors: Carvalho C, Slagmolen P, Bogaerts S, Scheys L, D'hooge J, Peers K, Maes F, Suetens P Abstract Estimation of strain in tendons for tendinopathy assessment is a hot topic within the sports medicine community. It is believed that, if accurately estimated, existing treatment and rehabilitation protocols can be improved and presymptomatic abnormalities can be detected earlier. State-of-the-art studies present inaccurate and highly variable strain estimates, leaving this problem without solution. Out-of-plane motion, present when acquiring two-dimensional (2D) ultrasound (US) images, is a known problem and may b...
Source: Ultrasonic Imaging - August 24, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Review of Ultrasound Tissue Characterization with Mean Scatterer Spacing.
Authors: Zhou Z, Wu W, Wu S, Jia K, Tsui PH Abstract Tissues exhibiting quasi-periodic structures can be modeled as a collection of diffuse scatterers and coherent scatterers. The mean scatterer spacing (MSS) of coherent and quasi-periodic components is directly related to tissue microstructure and has become an important quantitative ultrasound (QUS) parameter in the characterization of quasi-periodic tissues. In this paper, a review of the literature on the development of MSS as a QUS parameter was conducted. First, a unified theoretical background of MSS estimates was provided. Then, the application of MSS estim...
Source: Ultrasonic Imaging - August 13, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Influence of Tissue Microstructure on Shear Wave Speed Measurements in Plane Shear Wave Elastography: A Computational Study in Lossless Fibrotic Liver Media.
Authors: Wang Y, Jiang J Abstract Shear wave elastography (SWE) has been used to measure viscoelastic properties for characterization of fibrotic livers. In this technique, external mechanical vibrations or acoustic radiation forces are first transmitted to the tissue being imaged to induce shear waves. Ultrasonically measured displacement/velocity is then utilized to obtain elastographic measurements related to shear wave propagation. Using an open-source wave simulator, k-Wave, we conducted a case study of the relationship between plane shear wave measurements and the microstructure of fibrotic liver tissues. Par...
Source: Ultrasonic Imaging - July 21, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Effects of Phase Aberration and Phase Aberration Correction on the Minimum Variance Beamformer.
In this study, an analysis of the effects of aberration on conventional MV and eigenspace MV (ESMV) beamformers is carried out. In addition, the impact of three PAC algorithms on the performance of MV beamforming is analyzed. The different beamformers were tested on simulated data and on experimental data corrupted with electronic and tissue-based aberration. It is shown that all gains in performance of the MV beamformer with respect to delay-and-sum (DAS) are lost at high aberration strengths. For instance, with an electronic aberration of 60 ns, the lateral resolution of DAS degrades by 17% while MV degrades by 73% with ...
Source: Ultrasonic Imaging - July 15, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound.
This study provides a reliable method for further applications related to diagnoses of superficial organs. PMID: 28703685 [PubMed - as supplied by publisher] (Source: Ultrasonic Imaging)
Source: Ultrasonic Imaging - July 15, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Low-cost Volumetric Ultrasound by Augmentation of 2D Systems: Design and Prototype.
Authors: Herickhoff CD, Morgan MR, Broder JS, Dahl JJ Abstract Conventional two-dimensional (2D) ultrasound imaging is a powerful diagnostic tool in the hands of an experienced user, yet 2D ultrasound remains clinically underutilized and inherently incomplete, with output being very operator dependent. Volumetric ultrasound systems can more fully capture a three-dimensional (3D) region of interest, but current 3D systems require specialized transducers, are prohibitively expensive for many clinical departments, and do not register image orientation with respect to the patient; these systems are designed to provide ...
Source: Ultrasonic Imaging - July 12, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Material Properties of Human Ocular Tissue at 7- µm Resolution.
Material Properties of Human Ocular Tissue at 7-µm Resolution. Ultrason Imaging. 2017 Jul 01;:161734617713498 Authors: Rohrbach D, Ito K, Lloyd HO, Silverman RH, Yoshida K, Yamaguchi T, Mamou J Abstract Quantitative assessment of the material properties of ocular tissues can provide valuable information for investigating several ophthalmic diseases. Quantitative acoustic microscopy (QAM) offers a means of obtaining such information, but few QAM investigations have been conducted on human ocular tissue. We imaged the optic nerve (ON) and iridocorneal angle in 12-µm deparaffinized sections of...
Source: Ultrasonic Imaging - July 7, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Compressed Sensing for Elastography in Portable Ultrasound.
Authors: Shin B, Jeon S, Ryu J, Kwon HJ Abstract Portable ultrasound is recently emerging as a new medical imaging modality featuring high portability, easy connectivity, and real-time on-site diagnostic ability. However, it does not yet provide ultrasound elastography function that enables the diagnosis of malignant lesions using elastic properties. This is mainly due to the limitations of hardware performance and wireless data transfer speed for processing the large amount of data for elastography. Therefore, data transfer reduction is one of the feasible solutions to overcome these limitations. Recently, compres...
Source: Ultrasonic Imaging - July 5, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

GPU-accelerated Kernel Regression Reconstruction for Freehand 3D Ultrasound Imaging.
Authors: Wen T, Li L, Zhu Q, Qin W, Gu J, Yang F, Xie Y Abstract Volume reconstruction method plays an important role in improving reconstructed volumetric image quality for freehand three-dimensional (3D) ultrasound imaging. By utilizing the capability of programmable graphics processing unit (GPU), we can achieve a real-time incremental volume reconstruction at a speed of 25-50 frames per second (fps). After incremental reconstruction and visualization, hole-filling is performed on GPU to fill remaining empty voxels. However, traditional pixel nearest neighbor-based hole-filling fails to reconstruct volume with h...
Source: Ultrasonic Imaging - June 21, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Dynamic Transmit-Receive Beamforming by Spatial Matched Filtering for Ultrasound Imaging with Plane Wave Transmission.
Authors: Chen Y, Lou Y, Yen J Abstract During conventional ultrasound imaging, the need for multiple transmissions for one image and the time of flight for a desired imaging depth limit the frame rate of the system. Using a single plane wave pulse during each transmission followed by parallel receive processing allows for high frame rate imaging. However, image quality is degraded because of the lack of transmit focusing. Beamforming by spatial matched filtering (SMF) is a promising method which focuses ultrasonic energy using spatial filters constructed from the transmit-receive impulse response of the system. Stu...
Source: Ultrasonic Imaging - June 21, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Three-dimensional Ultrasound Elasticity Imaging on an Automated Breast Volume Scanning System.
Authors: Wang Y, Nasief HG, Kohn S, Milkowski A, Clary T, Barnes S, Barbone PE, Hall TJ Abstract 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 ul...
Source: Ultrasonic Imaging - June 8, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Quantitative Muscle Ultrasonography Using Textural Analysis in Amyotrophic Lateral Sclerosis.
Authors: Martínez-Payá JJ, Ríos-Díaz J, Del Baño-Aledo ME, Tembl-Ferrairó JI, Vazquez-Costa JF, Medina-Mirapeix F Abstract The purpose of this study was to analyze differences in gray-level co-occurrence matrix (GLCM) parameters, as assessed by muscle ultrasound (MUS), between amyotrophic lateral sclerosis (ALS) patients and healthy controls, and to compare the diagnostic accuracy of these GLCM parameters with first-order MUS parameters (echointensity [EI], echovariation [EV], and muscle thickness [MTh]) in different muscle groups. Twenty-six patients with ALS and 26 health...
Source: Ultrasonic Imaging - May 30, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Three-dimensional Simulation of Quantitative Ultrasound in Cancellous Bone Using the Echographic Response of a Metallic Pin.
Authors: Nagatani Y, Guipieri S, Nguyen VH, Chappard C, Geiger D, Naili S, Haїat G Abstract Degenerative discopathy is a common pathology that may require spine surgery. A metallic cylindrical pin is inserted into the vertebral body to maintain soft tissues and may be used as a reflector of ultrasonic wave to estimate bone density. The first aim of this paper is to validate a three-dimensional (3-D) model to simulate the ultrasonic propagation in a trabecular bone sample in which a metallic pin has been inserted. We also aim at determining the effect of changes of bone volume fraction (BV/TV) and of positioning er...
Source: Ultrasonic Imaging - May 13, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Frequency Representation: Visualization and Clustering of Acoustic Data Using Self-Organizing Maps.
In this study, frequency representation (FR) based on phase information in multispectral acoustic imaging (MSAI) is proposed to overcome the limit of intensity or amplitude information in image display. Experiments are performed on 3D acoustic data collected from a rigid surface engraved with five different letters. The results show that the proposed FR technique can not only identify the depth of the five letters by the colors representing frequency characteristics but also demonstrate the 3D image of the five letters, providing more detailed characteristics that are unavailable by conventional acoustic imaging. PMID:...
Source: Ultrasonic Imaging - May 6, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Diagnostic Value of Acoustic Radiation Force Impulse Quantification in the Differentiation of Benign and Malignant Thyroid Nodules.
The objective of this study was to evaluate the role of ultrasound elastography using acoustic radiation force impulse (ARFI) quantification in characterizing and differentiating malignant versus benign thyroid nodules. A total of 40 thyroid nodules were evaluated with conventional sonography and ultrasound elastography using ARFI quantification. The final diagnosis was obtained from histologic findings. A total of 14 malignant and 26 benign nodules were diagnosed on the basis of histologic examination. Majority of the malignant thyroid nodules demonstrated presence of intranodular vascular flow, hypoechoic echotexture, ab...
Source: Ultrasonic Imaging - May 6, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Lower Bound on Estimation Variance of the Ultrasonic Attenuation Coefficient Using the Spectral-Difference Reference-phantom Method.
Authors: Samimi K, Varghese T Abstract Ultrasonic attenuation is one of the primary parameters of interest in Quantitative Ultrasound (QUS). Non-invasive monitoring of tissue attenuation can provide valuable diagnostic and prognostic information to the physician. The Reference Phantom Method (RPM) was introduced as a way of mitigating some of the system-related effects and biases to facilitate clinical QUS applications. In this paper, under the assumption of diffuse scattering, a probabilistic model of the backscattered signal spectrum is used to derive a theoretical lower bound on the estimation variance of the at...
Source: Ultrasonic Imaging - April 22, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

High-Frequency Ultrasonic Imaging with Lead-free (Na,K)(Nb,Ta)O3 Single Crystal.
Authors: Chen Z, Zheng L, Cao W, Chen X, Chen R, Li R, Shung K, Zhou Q Abstract Lead-free (Na,K)(Nb,Ta)O3 (KNNT) piezoelectric single crystal has been successfully grown using the top-seeded solution growth technique. The electromechanical coupling factors are very high ( k33 = 0.827, kt = 0.646), and the dielectric loss tangent is as low as 0.004. Acoustic impedance was calculated to be 26.5 MRayl. From the single crystal, a single element transducer was fabricated. The transducer achieved a 57.6% -6 dB bandwidth and 32.3 µm axial resolution at the center frequency of 45.4 MHz, which can identify the cornea ...
Source: Ultrasonic Imaging - April 13, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Coaxial Dual-element Focused Ultrasound Probe for Guidance of Epidural Catheterization.
Authors: Dong GC, Chiu LC, Ting CK, Hsu JR, Huang CC, Chang Y, Chen GS Abstract Ultrasound guidance for epidural block has improved clinical blind-trial problems but the design of present ultrasonic probes poses operating difficulty of ultrasound-guided catheterization, increasing the failure rate. The purpose of this study was to develop a novel ultrasonic probe to avoid needle contact with vertebral bone during epidural catheterization. The probe has a central circular passage for needle insertion. Two focused annular transducers are deployed around the passage for on-axis guidance. A 17-gauge insulated Tuohy nee...
Source: Ultrasonic Imaging - March 28, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Rotation Elastogram Estimation Using Synthetic Transmit Aperture Technique.
Authors: B L, Chintada BR, Thittai AK Abstract It is well-documented in literature that benign breast lesions, such as fibroadenomas, are loosely bonded to their surrounding tissue and tend to slip under a small quasi-static compression, whereas malignant lesions being firmly bonded to their surrounding tissue do not slip. Recent developments in quasi-static ultrasound elastography have shown that an image of the axial-shear strain distribution can provide information about the bonding condition at the lesion-surrounding tissue boundary. Further studies analyzing the axial-shear strain elastograms revealed that non...
Source: Ultrasonic Imaging - January 18, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

Short-lag Spatial Coherence Ultrasound Imaging with Adaptive Synthetic Transmit Aperture Focusing.
Authors: Zhao J, Wang Y, Yu J, Guo W, Zhang S, Aliabadi S Abstract The short-lag spatial coherence (SLSC) imaging has been demonstrated to be advantageous over the traditional B-mode ultrasound imaging. With focused scanning beams, the SLSC imaging has an excellent performance in clutter reduction and lesion detection, especially in the low signal-to-noise ratio (SNR) scenarios. The synthetic aperture (SA) imaging is an appropriate mode for the SLSC imaging as the dynamic transmit focusing could keep a good focusing quality at any depth. However, the SLSC image may still suffer a bad resolution performance when a l...
Source: Ultrasonic Imaging - January 12, 2017 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Color Doppler Shear Wave Imaging Phase Reconstruction Method Using Four Color Flow Images.
This study investigates shear wave phase map reconstruction using a limited number of color flow images (CFIs) acquired with a color Doppler ultrasound imaging instrument. We propose an efficient reconstruction method to considerably reduce the number of CFIs required for reconstruction and compare this method with Fourier analysis-based color Doppler shear wave imaging. The proposed method uses a two-step phase reconstruction process, including an initial phase map derived from four CFIs using an advanced iterative algorithm of optical interferometry. The second step reduces phase artifacts in the initial phase map using ...
Source: Ultrasonic Imaging - December 3, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Effect of Interstitial Fluid Pressure on Ultrasound Axial Strain and Axial Shear Strain Elastography.
Authors: Chaudhry A, Kim N, Unnikrishnan G, Nair S, Reddy JN, Righetti R Abstract Ultrasound elastography is an imaging modality that has been used to diagnose tumors of the breast, thyroid, and prostate. Both axial strain elastography and axial shear strain elastography (ASSE) have shown significant potentials to differentiate between benign and malignant tumors. Elevated interstitial fluid pressure (IFP) is a characteristic of many malignant tumors and a major barrier in targeted drug delivery therapies. This parameter, however, has not received significant attention in ultrasound elastography and, in general, in...
Source: Ultrasonic Imaging - October 5, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Staging of Fatty Liver Diseases Based on Hierarchical Classification and Feature Fusion for Back-Scan-Converted Ultrasound Images.
This study is performed with 129 subjects including 28 normal, 47 steatosis, 42 fibrosis, and 12 cirrhosis images. The proposed approach uses back-scan conversion of ultrasound sector images and is based on a hierarchical classification. The proposed algorithm is performed in two parts. The first part selects the optimum regions of interest from the focal zone of the back-scan-converted ultrasound images. In the second part, discrimination between normal and fatty liver is performed and then steatosis, fibrosis, and cirrhosis are classified in a hierarchical basis. The wavelet packet transform and gray-level co-occurrence ...
Source: Ultrasonic Imaging - October 5, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

A Pilot Clinical Study in Characterization of Malignant Renal Cell Carcinoma Subtype with Contrast-Enhanced Ultrasound.
Authors: Kasoji SK, Chang EH, Mullin LB, Chong WK, Rathmell WK, Dayton PA Abstract Malignant renal cell carcinoma (RCC) is a diverse set of diseases, which are independently difficult to characterize using conventional MRI and CT protocols due to low temporal resolution to study perfusion characteristics. Because different disease subtypes have different prognoses and involve varying treatment regimens, the ability to determine RCC subtype non-invasively is a clinical need. Contrast-enhanced ultrasound (CEUS) has been assessed as a tool to characterize kidney lesions based on qualitative and quantitative assessment...
Source: Ultrasonic Imaging - September 25, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Virtual Breast Quasi-Static Elastography (VBQE): A Case Study in Contrast Transfer Efficiency of Viscoelastic Imaging.
In this study, our primary objective is to quantitatively evaluate the contrast transfer efficiency (CTE) of VEI, which contains useful information regarding image interpretations. Using an open-source simulator for virtual breast quasi-static elastography (VBQE), we conducted a case study of contrast transfer efficiency of VEI. In multiple three-dimensional (3D) numerical breast phantoms containing various degrees of heterogeneity, finite element (FE) simulations in conjunction with quasi-linear viscoelastic constitutive tissue models were performed to mimic data acquisition of VEI under freehand scanning. Our results sug...
Source: Ultrasonic Imaging - August 6, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Impact of Modified Anisotropic Diffusion-Based Enhancement Method in Computer-Aided Classification of Focal Liver Lesions.
Authors: Mittal D Abstract This work is presented with the objective to assess quantitatively the impact of modified anisotropic diffusion-based enhancement method of Mittal et al. in computer-aided classification of focal liver lesions. This assessment was made before and after enhancement of clinically acquired ultrasound images with the comparison of (a) discrimination capability of radiologically important texture contrast feature using box plot and p-value statistics and (b) test results of designed computer-aided classification schemes to detect/classify focal liver tissues using receiver operating characteri...
Source: Ultrasonic Imaging - June 25, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Computer-Aided Characterization and Diagnosis of Diffuse Liver Diseases Based on Ultrasound Imaging: A Review.
Authors: Bharti P, Mittal D, Ananthasivan R Abstract Diffuse liver diseases, such as hepatitis, fatty liver, and cirrhosis, are becoming a leading cause of fatality and disability all over the world. Early detection and diagnosis of these diseases is extremely important to save lives and improve effectiveness of treatment. Ultrasound imaging, a noninvasive diagnostic technique, is the most commonly used modality for examining liver abnormalities. However, the accuracy of ultrasound-based diagnosis depends highly on expertise of radiologists. Computer-aided diagnosis systems based on ultrasound imaging assist in fas...
Source: Ultrasonic Imaging - April 23, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Improvement of Lesion Detection by Complete Angular Compound Ultrasonic Elastography.
Authors: Liu C, Zhou Y Abstract Quasi -: static ultrasound elastography is an emerging diagnostic imaging modality for determining the stiffness of pathologically changed soft tissues, which do not show significant differences in acoustic impedance for B-mode imaging. Although some methods were applied to improve the signal-to-noise ratio (SNRe) and contrast-to-noise ratio (CNRe) of the constructed elastogram, nonuniform strain distribution at the internal boundary of a hard inclusion, even with the uniform displacement on the surface, is an inherent mechanical effect and results in distortion at the detected lesio...
Source: Ultrasonic Imaging - January 28, 2016 Category: Radiology Tags: Ultrason Imaging Source Type: research

Vector Flow Imaging Compared with Conventional Doppler Ultrasound and Thermodilution for Estimation of Blood Flow in the Ascending Aorta.
Authors: Hansen KL, Møller-Sørensen H, Kjaergaard J, Jensen MB, Lund JT, Pedersen MM, Olesen JB, Jensen JA, Nielsen MB Abstract Transverse oscillation (TO) is a real-time ultrasound vector flow method implemented on a commercial scanner. The TO setup was examined on a flowrig with constant and pulsatile flow. Subsequently, 25 patients undergoing cardiac bypass surgery were scanned intraoperatively with TO on the ascending aorta and compared to transesophageal echocardiography (TEE) and pulmonary artery catheter thermodilution (PACTD). On the flowrig, TO had a precision of 5.5%, 9.4% and 14.7%, a perce...
Source: Ultrasonic Imaging - December 27, 2015 Category: Radiology Tags: Ultrason Imaging Source Type: research

Foreword to the Special Issue of Ultrasonic Imaging on Biomedical Imaging with Combined Light and Sound.
Authors: Wang X, Feleppa E PMID: 26675216 [PubMed - in process] (Source: Ultrasonic Imaging)
Source: Ultrasonic Imaging - December 20, 2015 Category: Radiology Tags: Ultrason Imaging Source Type: research

Chirp-Coded Ultraharmonic Imaging with a Modified Clinical Intravascular Ultrasound System.
In this study, we evaluated the performance of chirp-coded ultraharmonic imaging using a modified IVUS system (iLab™, Boston Scientific/Scimed) equipped with clinically available peripheral and coronary imaging catheters. Flow phantoms perfused with a phospholipid-encapsulated contrast agent were visualized using ultraharmonic imaging at 12 MHz and 30 MHz transmit frequencies. Flow channels with diameters as small as 0.8 mm and 0.5 mm were visualized using the peripheral and coronary imaging catheters. Radio-frequency signals were acquired at standard IVUS rotation speed, which resulted in a frame rate of 30 frames/s...
Source: Ultrasonic Imaging - December 8, 2015 Category: Radiology Tags: Ultrason Imaging Source Type: research