Detection of Motion in Vibro-Acoustography

Harmonic motion is produced in a subject using vibro-acoustography. An ultrasonic imaging system repetitively interrogates the subject and the Doppler shift in the reflected echo signals is analyzed to measure the phase and amplitude of harmonic motion produced in the subject at different prescribed frequencies. Shear wave propagation through the subject is determined from this information and mechanical properties related to “stiffness” of the subject are determined. A Kalman filter is employed in the phase and amplitude measurement to extract the harmonic motion information from background noise. Patent No.: US 7,785,259 Date of Patent: Aug. 31, 2010 Filed: Oct 1, 2004 Int. Cl.: A61B 8/00 (2006-01) U.S. Cl.: 600/438; 600/441; 600/442; 600/ 444; 601/2; 606/128; 73/1-82; 73/1-89 CPC Cl.: A61B 5/0048 (2013.01); A61B 8/485 (2013.01); A61B 8/00 (2013.01) Field of Search: 600/437, 600/438, 441, 444, 442; 601/2; 606/128; 73/1 .82, 1.8

Parametric Amplification in the Dynamic Radiation Force of Acoustic Waves in Fluids

We report on parametric amplification in dynamic radiation force produced by a bichromatic acoustic beam in a fluid. To explain this effect we develop a theory taking into account the nonlinearity of the fluid. The theory is validated through an experiment to measure the dynamic radiation force on an acrylic sphere. Results exhibit an amplification of 66 dB in water and 80 dB in alcohol as the difference of the frequencies is increased from 10 Hz to 240 kHz

Carbon Sequestration in Relation to Shrub Size in the Desert Ecosystem

Desert ecosystems have been reported as the location of the long-sought ‘missing sink’ for atmospheric carbon dioxide and as a potentially important area for carbon sequestering from fossil fuel combustion in the future (Stone 2008). Researchers have found that net uptake of carbon in the Mojave Desert ranged from 102 to 127 g C m2/yr during a 3-year period, which is equivalent to the net ecosystem production of many forest ecosystems with a much higher biomass (Luyssaert et al. 2007; Wohlfahrt et al. 2008). Shrub is the dominant plant of desert ecosystems (Gratani et al. 2011); hence, it is important to understand the dynamics of carbon sequestration by shrubs as well as their role in desert ecosystem carbon balance. Information on the carbon sequestration associated with shrub size is limited. Our objective was, therefore, to find out the relationship between carbon sequestration potential and size of shrubs

Method for Ultrasound Vibrometry Using Orthogonal Basis Functions

A method for measuring a mechanical property of a subject includes using an ultrasound transducer to apply ultrasonic vibration pulses to a location in a subject in order to induce shear waves at multiple prescribed orthogonal frequencies in the subject. The ultrasound transducer is directed by an excitation signal that is composed of multiple orthogonal basis functions, each having a given frequency component corresponding to the prescribed orthogonal frequencies. The power level of each orthogonal basis function is independently adjustable. The excitation signal can be sparsely sampled, or portions of the excitation signal can be removed in order to improve tissue vibration and to provide for the interleaving ultrasonic vibration and detection pulses. Ultrasonic detection pulses are applied to at least one motion detection point, from which echo signals are received. From the received echo signals, a motion signal is determined, from which mechanical properties of the subject are calculated. Patent No.: US 8,602,994 Date of Patent: Dec 20, 2013 Filed: Mar 9, 2010 Int. Cl.: A61B 8/00 (2006.01); G01H 1/00 (2006.01) U.S. Cl.: 600/438; 73/579 CPC Cl.: G01S 7/52022 (2013.01); A61B 8/485 (2013.01); G01S 15/8952 (2013.01); G01S 7/52036 (2013.01) Field of Search: ;600/437,443 ;702/19,22 ;382/260 ;345/441,501,552 ;73/574,579,587,60

The Characters of Soil Microbial Biomass and Metabolic Quotient Associated with Shrub Development in the Arid Region

Soil microbial biomass (MBC), as the most active of soil organic constituents, controls many important ecological processes in the ecosystem including nutrient cycling and litter decomposition (Jia et al. 2010), and is considered to be the most sensitive biological indicator of soil quality (Sinha et al. 2009). Moreover, soil microbial metabolic quotient (qCO2) reflects the quantity and quality of soil organic matter, soil nutrient availability, microbial substrate utilization efficiency and ecosystem stability (Mao et al. 2010). Shrub is the dominant vegetation of desert ecosystems, contributing to soil nutrient conservation and carbon sequestration. Considerable research related to shrubs in desert ecosystems has been reported, however changes of soil microbial properties throughout the process of shrub development remains poorly documented. The main objective of this study was to explore how soil microbial biomass and qCO2 change with shrub development

Viscoelasticidad renal durante la disminución gradual de flujo sanguíneo en un modelo porcino in vivo: estudio piloto

Elasticity imaging methods have been used to study kidney mechanical properties and have demonstrated that the kidney elastic modulus increases with disease state. However, studies in swine suggest that kidney elastic modulus is also affected by hemodynamic variables. A newly emerging method called Shearwave Dispersion Ultrasound Vibrometry (SDUV) offers a tool to determine renal elasticity and viscosity in vivo. The purpose of this study was directed toward evaluating the feasibility of SDUV for in vivo measurements of healthy swine kidney during acute gradual decease of renal blood flow. In this study in vivo SDUV measurements were made on a group of 5 normal swine kidneys at baseline renal blood flow (RBF) and 25, 50, 75 and 100% decrease in RBF. The shear elastic modulus at full baseline was 7.04 ± 0.92 kPa and 3.48 ± 0.20 kPa at 100% decrease in RBF. The viscosity did not change between baseline (2.23 ± 0.33 Pa•s) and 100% decrease in RBF (2.03 ± 0.32 Pa•s). The data from this study indicates that other variables such as local blood flow, pressure and volume as well as method accuracy need to be measured to illustrate the relationship between shear elasticity and viscosity associated with acute kidney processes.Métodos de imágenes de elasticidad se han utilizado para estudiar las propiedades mecánicas renales y han demostrado que el módulo elástico de los riñones del aumenta con el estado de enfermedades renales. Sin embargo, estudios en cerdos sugieren que el riñón módulo elástico también se ve afectada por las variables hemodinámicas. Un método emergente llamado Shearwave Dispersion Ultrasound Vibrometry (SDUV) ofrece una herramienta para determinar la elasticidad y la viscosidad renal. El propósito de este estudio se dirige a la evaluación de la viabilidad de SDUV para mediciones las propiedades viscoelasticas del riñón saludable durante variación aguda del flujo sanguíneo renal. En este estudio el método SDUV se realizó en un grupo de 5 riñones porcinos normales al inicio del flujo sanguíneo renal (RBF) basal y 25, 50, 75 y 100% de disminución en el RBF. El módulo elástico basal fue de 7,04 ± 0,92 kPa y 3,48 ± 0,20 kPa a 100% de disminución del RBF. La viscosidad no cambió entre el momento basal (2,23 ± 0,33 Pa • s) y el 100% de disminución del RBF (2,03 ± 0,32 Pa • s). Los datos de este estudio indican que variables tales como el flujo local de sangre, la presión y el volumen así como el método exactitud deben ser medidos para ilustrar la relación entre la elasticidad y la viscosidad asociada con los procesos renales agudos

Functional Ultrasound Imaging of Spinal Cord Hemodynamic Responses to Epidural Electrical Stimulation: A Feasibility Study

This study presents the first implementation of functional ultrasound (fUS) imaging of the spinal cord to monitor local hemodynamic response to epidural electrical spinal cord stimulation (SCS) on two small and large animal models. SCS has been successfully applied to control chronic refractory pain and recently was evolved to alleviate motor impairment in Parkinson's disease and after spinal cord injury. At present, however, the mechanisms underlying SCS remain unclear, and current methods for monitoring SCS are limited in their capacity to provide the required sensitivity and spatiotemporal resolutions to evaluate functional changes in response to SCS. fUS is an emerging technology that has recently shown promising results in monitoring a variety of neural activities associated with the brain. Here we demonstrated the feasibility of performing fUS on two animal models during SCS. We showed in vivo spinal cord hemodynamic responses measured by fUS evoked by different SCS parameters. We also demonstrated that fUS has a higher sensitivity in monitoring spinal cord response than electromyography. The high spatial and temporal resolutions of fUS were demonstrated by localized measurements of hemodynamic responses at different spinal cord segments, and by reliable tracking of spinal cord responses to patterned electrical stimulations, respectively. Finally, we proposed optimized fUS imaging and post-processing methods for spinal cord. These results support feasibility of fUS imaging of the spinal cord and could pave the way for future systematic studies to investigate spinal cord functional organization and the mechanisms of spinal cord neuromodulation in vivo