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423 results on '"Varghese, Tomy"'

7. Methods in Stroke Prevention in the Wisconsin Native American Population.

Author

Cress, Hannah J., Mitchell, Carol C., Wilbrand, Stephanie M., Wesley, Umadevi V., Morel Valdés, Gloria M., Hess, Timothy, Varghese, Tomy, Maybock, Jenna, Metoxen, Melissa, Riesenberg, Amanda, Vandenberg, Connie, Blohowiak, Carrie J., Kennard, Jay, Danforth, Debra, and Dempsey, Robert J.

Subjects
NATIVE Americans, DISEASE risk factors, CEREBROVASCULAR disease, STROKE, CAROTID artery ultrasonography
Abstract

Native American individuals are more frequently affected by cerebrovascular diseases including stroke and vascular cognitive decline. The aim of this study was to determine stroke risk factors that are most prevalent in Wisconsin Native Americans and to examine how education at the community and individual level as well as intensive health wellness coaching may influence modification of stroke risk factors. Additionally, we will investigate the role novel stroke biomarkers may play in stroke risk in this population. This paper details the aims and methods employed in the "Stroke Prevention in the Wisconsin Native American Population" (clinicaltrials.gov identifier: NCT04382963) study including participant health assessments, clinical ultrasound exam of the carotid arteries, cognitive testing battery, and structure and execution of the coaching program. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Young's modulus reconstruction for radio-frequency ablation electrode-induced displacement fields: a feasibility study

Author

Jiang, Jingfeng, Varghese, Tomy, Brace, Christopher L., Madsen, Ernest L., Hall, Timothy J., Bharat, Shyam, Hobson, Maritza A., Zagzebski, James A., and Lee, Fred T., Jr.

Subjects
Algorithms -- Research, Radiofrequency ablation -- Research, Ultrasound imaging -- Research, Algorithm, Business, Electronics, Electronics and electrical industries, Health care industry
Published
2009

41. Estimation of the optimal maximum beam angle and angular increment for normal and shear strain estimation

Author

Rao, Min and Varghese, Tomy

Subjects
Shear (Mechanics) -- Observations, Elasticity -- Observations, Ultrasound imaging -- Methods, Ultrasound imaging -- Usage, Image processing -- Methods, Biological sciences, Business, Computers, Health care industry
Abstract

In the current practice of ultrasound elastography, only the axial component of the displacement vector is estimated and used to produce strain images. A method was recently proposed by our group to estimate both the axial and lateral components of a displacement vector using RF echo signal data acquired along multiple angular insonification directions of the ultrasound beam. Previous work has demonstrated that it is important to choose appropriate values for the maximum beam angle and angular increment to achieve optimal performance with this technique. In this paper, we present error propagation analysis using the least-square fitting process for the optimization of the angular increment and the maximum beam steered angle. Ultrasound simulations are performed to corroborate the theoretical prediction of the optimal values for the maximum beam angle and angular increment. Selection of the optimal parameters depends on system parameters, such as center frequency and aperture size. For typical system parameters, the optimal maximum beam angle is around 10[degrees] for axial strain estimation and around 15[degrees] for lateral strain estimation. The optimal angular increment is around 4[degrees]-6[degrees], which indicates that only five to seven beam angles are required for this strain-tensor estimation technique. Index Terms--Elasticity, elasticity imaging, elastogram, elastography, shear strain, strain, strain tensors, stiffness, ultrasound.

Published
2009

42. Estimation of ultrasound attenuation from broadband echo-signals using bandpass filtering

Author

Hyungsuk Kim, Zagzebski, James A., and Varghese, Tomy

Subjects
Narrowband transmission -- Analysis, Signal processing -- Analysis, Ultrasound imaging -- Analysis, Digital signal processor, Business, Electronics, Electronics and electrical industries
Abstract

The accuracy of video signal analysis (VSA) attenuation estimates computed for B-mode images obtained after bandpass filtering of the broadband echo signals is evaluated. Unbiased attenuation estimation was provided by the narrowband VSA for frequencies lower than or at the center frequency of the broadband pulse.

Published
2008

43. Correlation analysis for angular compounding in strain imaging

Author

Rao, Min and Varghese, Tomy

Subjects
Image processing -- Methods, Signal processing -- Methods, Digital signal processor, Business, Electronics, Electronics and electrical industries
Abstract

The study presents a theoretical analysis of the correlation between the various echo signals for spatial angular compounding in strain imaging. The results show that an increase in the applied stress increases the beam-steered insonification angle, which in turn increases the signal decorrelation.

Published
2007

44. Attenuation estimation using spectral cross-correlation

Author

Hyungsuk Kim and Varghese, Tomy

Subjects
Attenuation -- Analysis, Tissues -- Diagnosis, Diagnosis, Ultrasonic -- Methods, Estimation theory -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

A novel estimation method is described by using spectral cross-correlation between consecutive power spectra obtained from the backscattered radio frequency (RF) signals at different depths in order to estimate the local attenuation coefficient. The simulation results have shown that the local attenuation coefficient estimates obtained from spectral cross-correlation are within 2.3% of the actual value with small estimation variances.

Published
2007

46. The Ultrasonix 500RP: A commercial ultrasound research interface

Author

Wilson, Thaddeus, Zagzebski, James, Varghese, Tomy, Quan Chen, and Min Rao

Subjects
Image processing -- Methods, Business, Electronics, Electronics and electrical industries
Abstract

An ultrasound research platform is described that allows easy access to raw radio frequency (RF) data as well as user software control over many system functions. The Ultrasonix 500RP system has provided research access to the data at multiple points in the signal processing chain and has allowed control over most imaging parameters.

Published
2006

47. Correlation of RF signals during angular compounding

Author

Quan Chen, Gerig, Anthony L., Techavipoo, Udomchai, Zagzebski, James A., and Varghese, Tomy

Subjects
Data entry -- Methods, Ultrasound imaging -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A theoretical analysis of the correlation between radio-frequency (RF) echo signal data acquired from the same location but at different angles is presented. Theoretical results provide a clear understanding of angular compounding techniques used to improve the signal-to-noise ratio in ultrasonic parametric imaging and in elastography.

Published
2005

48. Improved parametric imaging of scatterer estimates using angular compounding

Author

Gerig, Anthony L., Varghese, Tomy, and Zagzebski, James A.

Subjects
Ultrasound imaging -- Research, Image processing -- Analysis, Business, Electronics, Electronics and electrical industries
Abstract

A phased-array transducer is translated using a precision linear stage to acquire radio frequency (RF) data from locations in a phantom at different incident angles. It is observed that the resultant scatterer-size images exhibit higher signal-to-noise ratio (SNR) with greater degrees of angular compounding.

Published
2004

49. Noise reduction using spatial-angular compounding for elastography

Author

Udomchai Techavipoo, Quan Chen, Varghese, Tomy, Zagzebski, James A., and Madsen, Ernest L.

Subjects
Ultrasonics -- Research, Ultrasound imaging -- Methods, Ultrasound imaging -- Product enhancement, Product enhancement, Business, Electronics, Electronics and electrical industries
Abstract

Ultrasound elastography is developed into an imaging modality suitable for detection and diagnosis of cancers in breast, prostrate and thyroid. A new approach is described that enables the reduction of noise artifacts in elastography without significant reduction in either the contrast or spatial resolution.

Published
2004

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