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Your search keyword '"Aristizabal, Sara"' showing total 46 results
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46 results on '"Aristizabal, Sara"'

4. The impact of automated control of indoor air pollutants on cardiopulmonary health, environmental comfort, sleep quality in a simulated apartment: A crossover experiment protocol

Author

Pantelic, Jovan, primary, Aristizabal, Sara, additional, Liu, Qingyang, additional, Senerat, Araliya, additional, Son, Young Joo, additional, Byun, Kunjoon, additional, Li, Linhao, additional, Mullan, Aidan, additional, Zhang, Rongpeng, additional, Johnson, Bruce D., additional, and Clements, Nicholas, additional

Published
2023
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15. Living Labs

Author

Hasan, Syed Shabih, primary, Jamrozik, Anja, additional, Campanella, Carolina, additional, Aristizabal, Sara, additional, Zhang, Rongpeng, additional, and Clements, Nicholas, additional

Published
2018
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18. I have an accent.

Author

Aristizabal, Sara

Subjects
HEART beat, UNIVERSAL language
Published
2023

22. Characterization of transverse isotropy in compressed tissue mimicking phantoms

Author

Urban, Matthew W., Lopera, Manuela, Aristizabal, Sara, Amador, Carolina, Nenadic, Ivan, Kinnick, Randall R., Weston, Alexander D., Qiang, Bo, Zhang, Xiaoming, and Greenleaf, James F.

Subjects
Agar, Phantoms, Imaging, Physics::Medical Physics, Elasticity Imaging Techniques, Gelatin, Models, Biological, Article
Abstract

Tissues such as skeletal muscle and kidneys have well-defined structure that affects the measurements of mechanical properties. As an approach to characterize the material properties of these tissues, different groups have assumed that they are transversely isotropic (TI) and measure the shear wave velocity as it varies with angle with respect to the structural architecture of the organ. To refine measurements in these organs, it is desirable to have tissue-mimicking phantoms that exhibit similar anisotropic characteristics. Some approaches involve embedding fibers into a material matrix. However, if a homogeneous solid is under compression due to a static stress, an acoustoelastic effect can manifest that makes the measured wave velocities change with the compression stress. We propose to exploit this characteristic to demonstrate that stressed tissue mimicking phantoms can be characterized as a TI material. We tested six phantoms made with different concentrations of gelatin and agar. Stress was applied by the weight of a water container centered on top of a plate on top of the phantom. A linear array transducer and a V-1 Verasonics system were used to induce and measure shear waves in the phantoms. The shear wave motion was measured using a compound plane wave imaging technique. Autocorrelation was applied to the received in-phase/quadrature data. The shear wave velocity, c, was estimated using a Radon transform method. The transducer was mounted on a rotating stage so measurements were made every 10° over a range of 0° to 360°, where the stress is applied along 0° to 180° direction. The shear moduli were estimated. A TI model was fit to the data and the fractional anisotropy was evaluated. This approach can be used to explore many configurations of transverse isotropy with the same phantom, simply by applying stress to the tissue-mimicking phantom.

Published
2014

46. Phase Aberration and Attenuation Effects on Acoustic Radiation Force-Based Shear Wave Generation.

Author

Carrascal CA, Aristizabal S, Greenleaf JF, and Urban MW

Subjects
Abdomen diagnostic imaging, Acoustics, Animals, Finite Element Analysis, Image Processing, Computer-Assisted, Swine, Elasticity Imaging Techniques methods, Models, Biological
Abstract

Elasticity is measured by shear wave elasticity imaging (SWEI) methods using acoustic radiation force to create the shear waves. Phase aberration and tissue attenuation can hamper the generation of shear waves for in vivo applications. In this study, the effects of phase aberration and attenuation in ultrasound focusing for creating shear waves were explored. This includes the effects of phase shifts and amplitude attenuation on shear wave characteristics such as shear wave amplitude, shear wave speed, shear wave center frequency, and bandwidth. Two samples of swine belly tissue were used to create phase aberration and attenuation experimentally. To explore the phase aberration and attenuation effects individually, tissue experiments were complemented with ultrasound beam simulations using fast object-oriented C++ ultrasound simulator (FOCUS) and shear wave simulations using finite-element-model (FEM) analysis. The ultrasound frequency used to generate shear waves was varied from 3.0 to 4.5 MHz. Results: The measured acoustic pressure and resulting shear wave amplitude decreased approximately 40%-90% with the introduction of the tissue samples. Acoustic intensity and shear wave displacement were correlated for both tissue samples, and the resulting Pearson's correlation coefficients were 0.99 and 0.97. Analysis of shear wave generation with tissue samples (phase aberration and attenuation case), measured phase screen, (only phase aberration case), and FOCUS/FEM model (only attenuation case) showed that tissue attenuation affected the shear wave generation more than tissue aberration. Decreasing the ultrasound frequency helped maintain a focused beam for creation of shear waves in the presence of both phase aberration and attenuation.

Published
2016
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