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Ultrasonic Imaging

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https://www.readbyqxmd.com/read/27903789/a-color-doppler-shear-wave-imaging-phase-reconstruction-method-using-four-color-flow-images
#1
Naoki Sunaguchi, Yoshiki Yamakoshi, Takahito Nakajima
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...
November 30, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/27694129/effect-of-interstitial-fluid-pressure-on-ultrasound-axial-strain-and-axial-shear-strain-elastography
#2
Anuj Chaudhry, Namhee Kim, Ginu Unnikrishnan, Sanjay Nair, J N Reddy, Raffaella Righetti
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 most diagnostic imaging modalities yet...
September 29, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/27659687/a-pilot-clinical-study-in-characterization-of-malignant-renal-cell-carcinoma-subtype-with-contrast-enhanced-ultrasound
#3
Sandeep K Kasoji, Emily H Chang, Lee B Mullin, Wui K Chong, W Kimryn Rathmell, Paul A Dayton
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 of perfusion patterns, and we hypothesize that this technique might help differentiate disease subtypes...
September 22, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26586725/segmentation-of-breast-lesions-in-ultrasound-images-through-multiresolution-analysis-using-undecimated-discrete-wavelet-transform
#4
K M Prabusankarlal, P Thirumoorthy, R Manavalan
Earliest detection and diagnosis of breast cancer reduces mortality rate of patients by increasing the treatment options. A novel method for the segmentation of breast ultrasound images is proposed in this work. The proposed method utilizes undecimated discrete wavelet transform to perform multiresolution analysis of the input ultrasound image. As the resolution level increases, although the effect of noise reduces, the details of the image also dilute. The appropriate resolution level, which contains essential details of the tumor, is automatically selected through mean structural similarity...
November 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26578642/segmental-analysis-of-cardiac-short-axis-views-using-lagrangian-radial-and-circumferential-strain
#5
Chi Ma, Xiao Wang, Tomy Varghese
Accurate description of myocardial deformation in the left ventricle is a three-dimensional problem, requiring three normal strain components along its natural axis, that is, longitudinal, radial, and circumferential strains. Although longitudinal strains are best estimated from long-axis views, radial and circumferential strains are best depicted in short-axis views. An algorithm that utilizes a polar grid for short-axis views previously developed in our laboratory for a Lagrangian description of tissue deformation is utilized for radial and circumferential displacement and strain estimation...
November 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26614530/experimental-validation-of-arfi-surveillance-of-subcutaneous-hemorrhage-assh-using-calibrated-infusions-in-a-tissue-mimicking-model-and-dogs
#6
Rebecca E Geist, Chase H DuBois, Timothy C Nichols, Melissa C Caughey, Elizabeth P Merricks, Robin Raymer, Caterina M Gallippi
Acoustic radiation force impulse (ARFI) Surveillance of Subcutaneous Hemorrhage (ASSH) has been previously demonstrated to differentiate bleeding phenotype and responses to therapy in dogs and humans, but to date, the method has lacked experimental validation. This work explores experimental validation of ASSH in a poroelastic tissue-mimic and in vivo in dogs. The experimental design exploits calibrated flow rates and infusion durations of evaporated milk in tofu or heparinized autologous blood in dogs. The validation approach enables controlled comparisons of ASSH-derived bleeding rate (BR) and time to hemostasis (TTH) metrics...
September 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26400676/a-review-of-intravascular-ultrasound-based-multimodal-intravascular-imaging-the-synergistic-approach-to-characterizing-vulnerable-plaques
#7
Teng Ma, Bill Zhou, Tzung K Hsiai, K Kirk Shung
Catheter-based intravascular imaging modalities are being developed to visualize pathologies in coronary arteries, such as high-risk vulnerable atherosclerotic plaques known as thin-cap fibroatheroma, to guide therapeutic strategy at preventing heart attacks. Mounting evidences have shown three distinctive histopathological features-the presence of a thin fibrous cap, a lipid-rich necrotic core, and numerous infiltrating macrophages-are key markers of increased vulnerability in atherosclerotic plaques. To visualize these changes, the majority of catheter-based imaging modalities used intravascular ultrasound (IVUS) as the technical foundation and integrated emerging intravascular imaging techniques to enhance the characterization of vulnerable plaques...
September 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26376923/indentation-measurements-to-validate-dynamic-elasticity-imaging-methods
#8
Khaldoon N Altahhan, Yue Wang, Nahil Sobh, Michael F Insana
We describe macro-indentation techniques for estimating the elastic modulus of soft hydrogels. Our study describes (a) conditions under which quasi-static indentation can validate dynamic shear-wave imaging estimates and (b) how each of these techniques uniquely biases modulus estimates as they couple to the sample geometry. Harmonic shear waves between 25 and 400 Hz were imaged using ultrasonic Doppler and optical coherence tomography methods to estimate shear dispersion. From the shear-wave speed of sound, average elastic moduli of homogeneous samples were estimated...
September 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26346886/can-elastography-predict-growth-of-incidental-thyroid-nodules-a-pilot-two-year-follow-up-study
#9
Anne Krejbjerg, Inge Bülow Pedersen, Peter Laurberg
The objective of this study was to examine the ultrasonography (US) and ultrasound elastography (USE) features of thyroid incidentalomas in a population exposed to iodine deficiency and to investigate whether baseline elasticity scores (ES) predicted changes in thyroid nodule US characteristics. We conducted a two-year follow-up pilot study of thyroid incidentalomas by US and USE. One sonographer performed the US and USE examination on the same apparatus at baseline and at follow-up. We evaluated 83 incidental thyroid nodules detected in a population study...
September 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/27488348/virtual-breast-quasi-static-elastography-vbqe-a-case-study-in-contrast-transfer-efficiency-of-viscoelastic-imaging
#10
David Rosen, Yu Wang, Jingfeng Jiang
Viscoelasticity Imaging (VEI) has been proposed to measure relaxation time constants for characterization of in vivo breast lesions. In this technique, an external compression force on the tissue being imaged is maintained for a fixed period of time to induce strain creep. A sequence of ultrasound echo signals is then utilized to generate time-resolved strain measurements. Relaxation time constants can be obtained by fitting local time-resolved strain measurements to a viscoelastic tissue model (e.g., a modified Kevin-Voigt model)...
August 2, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26416839/backscatter-difference-measurements-of-cancellous-bone-using-an-ultrasonic-imaging-system
#11
Brent K Hoffmeister, Morgan R Smathers, Catherine J Miller, Joseph A McPherson, Cameron R Thurston, P Luke Spinolo, Sang-Rok Lee
Backscatter-difference measurements may be used to detect changes in bone caused by osteoporosis. The backscatter-difference technique measures the power difference between two portions of an ultrasonic backscatter signal. The goal of this study is to evaluate the feasibility of using an ultrasonic imaging system to perform backscatter-difference measurements of bone. Ultrasonic images and backscatter signals were acquired from 24 specimens of human cancellous bone. The signals were analyzed in the frequency domain to determine the normalized mean backscatter-difference (nMBD) and in the time domain to determine the normalized backscatter amplitude ratio (nBAR)...
July 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26333280/combining-the-apes-and-minimum-variance-beamformers-for-adaptive-ultrasound-imaging
#12
Babak Mohammadzadeh Asl
In recent years, adaptive minimum-variance (MV) beamforming has been successfully applied to medical ultrasound imaging, resulting in simultaneous improvement in imaging resolution and contrast. MV has high resolution and hence can provide accurate estimates of the target locations. However, the MV amplitude estimates are significantly biased downward, especially when occurring the errors in model parameters. The amplitude and phase estimation (APES) beamformer gives much more accurate amplitude estimates at the target locations, but at the cost of lower resolution...
July 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26316172/nonlocal-total-variation-based-speckle-filtering-for-ultrasound-images
#13
Tiexiang Wen, Jia Gu, Ling Li, Wenjian Qin, Lei Wang, Yaoqin Xie
Ultrasound is one of the most important medical imaging modalities for its real-time and portable imaging advantages. However, the contrast resolution and important details are degraded by the speckle in ultrasound images. Many speckle filtering methods have been developed, but they are suffered from several limitations, difficult to reach a balance between speckle reduction and edge preservation. In this paper, an adaptation of the nonlocal total variation (NLTV) filter is proposed for speckle reduction in ultrasound images...
July 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26294659/handheld-thermoacoustic-scanning-system-based-on-a-linear-array-transducer
#14
Zhong Ji, Wenzheng Ding, Fanghao Ye, Cunguang Lou
To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally...
July 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/27333883/impact-of-modified-anisotropic-diffusion-based-enhancement-method-in-computer-aided-classification-of-focal-liver-lesions
#15
Deepti Mittal
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 characteristic curves...
June 22, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/27694278/staging-of-fatty-liver-diseases-based-on-hierarchical-classification-and-feature-fusion-for-back-scan-converted-ultrasound-images
#16
Mehri Owjimehr, Habibollah Danyali, Mohammad Sadegh Helfroush, Alireza Shakibafard
Fatty liver disease is progressive and may not cause any symptoms at early stages. This disease is potentially fatal and can cause liver cancer in severe stages. Therefore, diagnosing and staging fatty liver disease in early stages is necessary. In this paper, a novel method is presented to classify normal and fatty liver, as well as discriminate three stages of fatty liver in ultrasound images. This study is performed with 129 subjects including 28 normal, 47 steatosis, 42 fibrosis, and 12 cirrhosis images...
June 8, 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26157039/doppler-tissue-evaluation-of-atrial-conduction-properties-in-patients-with-non-alcoholic-fatty-liver-disease
#17
Olcay Ozveren, Cemil Izgi, Elif Eroglu, Mustafa Aytek Simsek, Ayca Turer, Zekeriya Kucukdurmaz, Veysel Cinar, Muzaffer Degertekin
Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in clinical practice, and there is an increasing trend in its prevalence in the general population. Recent studies have demonstrated increased risk of atrial fibrillation (AF) in NAFLD. However, information on the mechanism of increased risk of AF in NAFLD is lacking. Impaired atrial conduction is an important factor in the pathophysiology of AF. We aimed to investigate atrial conduction properties in patients with NAFLD by tissue Doppler echocardiography...
May 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26062760/breast-lesion-segmentation-combining-b-mode-and-elastography-ultrasound
#18
Gerard Pons, Joan Martí, Robert Martí, Sergi Ganau, J Alison Noble
Breast ultrasound (BUS) imaging has become a crucial modality, especially for providing a complementary view when other modalities (i.e., mammography) are not conclusive in the task of assessing lesions. The specificity in cancer detection using BUS imaging is low. These false-positive findings often lead to an increase of unnecessary biopsies. In addition, increasing sensitivity is also challenging given that the presence of artifacts in the B-mode ultrasound (US) images can interfere with lesion detection...
May 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/26025578/improved-correlation-of-strain-indices-with-cognitive-dysfunction-with-inclusion-of-adventitial-layer-with-carotid-plaque
#19
X Wang, C C Mitchell, T Varghese, D C Jackson, B G Rocque, B P Hermann, R J Dempsey
Plaque instability may lead to chronic embolization, which in turn may contribute to progressive cognitive decline. Accumulated strain tensor indices over a cardiac cycle within a pulsating carotid plaque may be viable biomarkers for the diagnosis of plaque instability. Using plaque-only carotid artery segmentations, we recently demonstrated that impaired cognitive function correlated significantly with maximum axial and lateral strain indices within a localized region of interest in plaque. Inclusion of the adventitial layer focuses our strain or instability measures on the vessel wall-plaque interface hypothesized to be a region with increased shearing forces and measureable instability...
May 2016: Ultrasonic Imaging
https://www.readbyqxmd.com/read/25900969/computational-complexity-reduction-of-synthetic-aperture-focus-in-ultrasound-imaging-using-frequency-domain-reconstruction
#20
Elahe Moghimirad, Ali Mahloojifar, Babak Mohammadzadeh Asl
A new frequency-domain implementation of a synthetic aperture focusing technique is presented in the paper. The concept is based on synthetic aperture radar (SAR) and sonar that is a developed version of the convolution model in the frequency domain. Compared with conventional line-by-line imaging, synthetic aperture imaging has a better resolution and contrast at the cost of more computational load. To overcome this problem, point-by-point reconstruction methods have been replaced by block-processing algorithms in radar and sonar; however, these techniques are relatively unknown in medical imaging...
May 2016: Ultrasonic Imaging
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