A model for estimating ultrasound attenuation along the propagation path to the fetus from backscattered waveforms

Accurate estimates of the ultrasound pressure and/or intensity incident on the developing fetus on a patient-specific basis could improve the diagnostic potential of medical ultrasound by allowing the clinician to increase the transmit power while still avoiding the potential for harmful bioeffects. Neglecting nonlinear effects, the pressure/intensity can be estimated if an accurate estimate of the attenuation along the propagation path ͑i.e., total attenuation͒ can be obtained. Herein, a method for determining the total attenuation from the backscattered power spectrum from the developing fetus is proposed. The boundaries between amnion and either the fetus' skull or soft tissue are each modeled as planar impedance boundaries at an unknown orientation with respect to the sound beam. A mathematical analysis demonstrates that the normalized returned voltage spectrum from this model is independent of the planes orientation. Hence, the total attenuation can be estimated by comparing the location of the spectral peak in the reflection from the fetus to the location of the spectral peak in a reflection obtained from a rigid plane in a water bath. The independence of the attenuation estimate and plane orientation is then demonstrated experimentally using a Plexiglas plate, a rat's skull, and a tissue-mimicking phantom

Improved estimation of parameters of the homodyned K distribution

Abstract-The amplitude distribution of the envelope of backscattered ultrasound depends on tissue microstructure. By fitting measured envelope data to a model, parameters can be estimated to describe properties of underlying tissue. The homodyned K distribution is a general model that encompasses the scattering situations modeled by the Rice, Rayleigh, and K distributions. However, parameter estimation for the homodyned K distribution is not straightforward because the model is analytically complex. Furthermore, effects of frequency-dependent attenuation on parameter estimates need to be assessed. An improved parameter estimation algorithm was developed to quickly and accurately estimate parameters of the homodyned K distribution, i.e., the μ (effective number of scatterers per resolution cell) and k (ratio of coherent to diffuse energy) parameters. Parameter estimates were found by fitting estimates of SNR, skewness, and kurtosis of fractional-order moments of the envelope with theoretical values predicted by the homodyned K distribution. The effects of frequency dependent attenuation were approximated by assuming a Gaussian pulse to determine the shift in center frequency of the pulse and hence change in volume of the resolution cell. Computational phantoms were created with varying attenuation coefficients and scanned using a simulated f/4 transducer with a center frequency of 10 MHz. An average of two scatterers per resolution cell (based on the phantoms with no attenuation) was used. The new estimation algorithm was tested and compared with an existing algorithm (based on the even moments of the homodyned K distribution). The new estimation algorithm was found to produce estimates with lower bias and variance. For example, for μ = 2 and k ranging from 0 to 2 in steps of 0.1, the average variance in the μ parameter estimates was 0.067 for the new algorithm and 0.42 for existing algorithm. For the k parameter estimates, the average variance was 0.0069 for the new algorithm and 0.048 for the old algorithm. In the simulations with no attenuation, the μ parameter estimate was 2.53±0.18. In the phantoms with a linear attenuation coefficient of 0.5 dB·MHz -1 ·cm -1 , the estimate was 4.64±0.54. This compared well with the predicted μ value of 4.98

The Cowl - v.30 - n.15 - Mar 20, 1968

The Cowl - student newspaper of Providence College. Volume 30, Number 15 - March 20, 1968. 10 pages

NON-INVASIVE IN VIVU TEhlPERATURE MAPPING OF ULTRASOUND HEATING USING MAGNETIC RESONANCE TECHNIQUES

Abstract-A major problem with conventional methods of measuring heating in vhu is that they are invasive and therefore interfere with heat propagation. A sensitive non-invasi\v method for temperature measurement using in \ivo magnetic resonance spectroscopy (MRS) of the temperature dependent chemical shift of the cobalt(II1) nucleus has been developed. Initial experiments demonstrate that this technique can be used to measure ultrasound induced temperature changes in the liver. Tris(ethy1enediamine) cobalt(II1) trichloride was encapsulated in liposomes and injected into seven rats. Heating was performed using a calibrated unfocused transducer operating at 3.41 MHz. After 5 minutes of CW ultrasound exposure, the chemical shift of the cobalt complex indicated that the temperature rise within the liver was 2.0k1.2 OC. This was seen to return to normal upon cessation of heating. The acoustic power was determined in a water bath using a calibrated hydrophone. Theoretical calculations based on the transducer calibration characteristics using the monopole-source solution for estimating tissue temperature increase yielded 2.0 OC based on steady state conditions. These results indicate that experimental values agree with the heating theory

Meeting Minutes: Minutes Duval County Hospital Authority , 1969-11-25

Meeting minutes of the Duval County Hospital Authority. The meeting discussed new names for the hospital, public relations activities, and a financial bid for cobalt that is essential laboratory equipment

Spring Commencement [Program], May 27, 1947

The program of the commencement ceremonies, including a list of institutional leadership, a list of the departments by college, awards given at the ceremonies, and a list of undergraduate and graduate degree candidates.https://scholarworks.uni.edu/commencement_programs/1164/thumbnail.jp

GPR Application – Non-destructive Technology for Verification of Thicknesses of Newly Paved Roads in Slovakia

AbstractThe paper focuses on the use of non-destructive testing technology for measurement of asphalt and unbound pavement structure layer thicknesses for quality control and quality assurance within the context of civil engineering project handover process. In addition to layer thickness information, the pavement roughness was also verified using 3D accelerometer technique and IRI parameters were calculated and analyzed. This presentation summarizes the technology and results of a project where a special section of highway R2 Žiar nad Hronom bypass in the length of 5.2km was selected for the non-destructive testing. The processing and interpretation consists of extensive data sets presented as longitudinal profiles from survey of each lane of road. The designed layer thicknesses of the road were then compared with measured thickness data. In addition, a comprehensive presentation of the results in GIS view was produced to ensure the subsequent decision-making process easy to execute

Antigenic Profile of African Horse Sickness Virus Serotype 4 VP5 and Identification of a Neutralizing Epitope Shared with Bluetongue Virus and Epizootic Hemorrhagic Disease Virus

AbstractAfrican horse sickness virus (AHSV) causes a fatal disease in horses. The virus capsid is composed of a double protein layer, the outermost of which is formed by two proteins: VP2 and VP5. VP2 is known to determine the serotype of the virus and to contain the neutralizing epitopes. The biological function of VP5, the other component of the capsid, is unknown. In this report, AHSV VP5, expressed in insect cells alone or together with VP2, was able to induce AHSV-specific neutralizing antibodies. Moreover, two VP5-specific monoclonal antibodies (MAbs) that were able to neutralize the virus in a plaque reduction assay were generated. To dissect the antigenic structure of AHSV VP5, the protein was cloned inEscherichia coliusing the pET3 system. The immunoreactivity of both MAbs, and horse and rabbit polyclonal antisera, with 17 overlapping fragments from VP5 was analyzed. The most immunodominant region was found in the N-terminal 330 residues of VP5, defining two antigenic regions, I (residues 151–200) and II (residues 83–120). The epitopes were further defined by PEPSCAN analysis with 12mer peptides, which determined eight antigenic sites in the N-terminal half of the molecule. Neutralizing epitopes were defined at positions 85–92 (PDPLSPGE) for MAb 10AE12 and at 179–185 (EEDLRTR) for MAb 10AC6. Epitope 10AE12 is highly conserved between the different orbiviruses. MAb 10AE12 was able to recognize bluetongue virus VP5 and epizootic hemorrhagic disease virus VP5 by several techniques. These data will be especially useful for vaccine development and diagnostic purposes

Montana Kaimin, September 30, 1981

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/8234/thumbnail.jp