Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

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Title Comments on a recent paper by heuter et al. on ultrasonic lesions in the central nervous system.
Author Fry WJ.
Journal J Acoust Soc Am
Volume
Year 1956
Abstract The recent paper by Hueter et al. on ultrasonic lesions in the central nervous system, which appeared in a recent issue of this Journal (March, 1956), presents a rather limited view of this field and may lead to some misunderstandings.This note is a critical analysis of the Hueter paper. Some of the more important points discussed are: (1) The unique advantages of producing ultrasonic lesions in the brain by using dosages appropriate for selective action combined with focusing of the beam in contrast to the use of focusing alone. (2) The choice of an irradiation procedure in experiments designed for the elucidation of physical mechanisms of the action of ultrasound on tissue. (3) The specification of the acoustic variables required for a dosage description. (4) The inapplicability of Eyring's theory of viscosity, plasticity, and diffusion to the elucidation of observed dosage relations. (5) The clarification of the usage of the terminology, nontemperature effects. (6) The applicability of the reciprocity method for the calibration of thermo-couple probes.


Title Comments on a recent paper on cerebral ultrasonic irradiation.
Author Fry WJ.
Journal Ultrasonics
Volume
Year 1956
Abstract The purpose of this note is to first correct some recent misquoting of our work by Dr. P. A. Lindstr?m in a recent article 6), second, to comment on some statements by the same investigator, which have appeared in the literature 6,7) regarding the acoustic properties of brain tissue and the applicability of ultrasound in the production of localized lesions in the central nervous system.


Title Comparative analysis of logistic regression and artificial neural network for computer-aided diagnosis of breast masses.
Author Song JH, Venkatesh SS, Conant EA, Arger PH, Sehgal CM.
Journal Acad Radiol
Volume
Year 2005
Abstract Rationale and Objective. To compare logistic regression and artificial neural network for computer-aided diagnosis on breast sonograms. Materials and Methods. Ultrasound images of 24 malignant and 30 benign masses were analyzed quantitatively for margin sharpness, margin echogenicity, and angular variation in margin. These features and age of patients were used with two pattern classifiers, logistic regression, and an artificial neural network to differentiate between malignant and benign masses. The performance of two methods was compared by receiver operating characteristic (ROC) analysis. Results. The area under the ROC curve Az (+/- SD) of the logistic regression analysis was 0.853 +/- 0.059 with 95% confidence limit (0.760 ? 0.950). The area under the ROC curve of the artificial neural network analysis was 0.856 +/- 0.058 with 95% confidence limit (0.734 ? 0.936). Although both the logistic regression and the artificial neural network has the same area under the ROC curve, the shapes of two curves were different. At 95% sensitivity, the artificial neural network had 76.5% specificity, whereas logistic regression had 64.7% specificity. Conclusion. There was no difference in performance between logistic regression and the artificial neural network as measured by the area under the ROC curve. However at a fixed 95% sensitivity, the artificial neural network had higher (12%) specificity compared with logistic regression value.


Title Comparative study of the efficiency of short-wave, microwave and ultrasonic diathermy in heating the hip joint.
Author Lehmann JF, McMillan JA, Brunner GD, Blumberg JB.
Journal Arch Phys Med Rehabil
Volume
Year 1959
Abstract It is demonstrated in this study that the temperature of the hip joint could be raised to any desired level by application of ultrasound. Since the rise of temperature measured in that part of the joint directly exposed to ultrasound was much greater than that recorded where the ultrasonic beam had first traversed the bone, it seems advisable to treat the joint from all aspects. Readily accessible for treatment in the human are the anterior, superior, and posterior aspects of the hip. Microwave and short-wave diathermy did not produce a temperature within the therapeutic range in the hip joint. It is assumed that the experimental findings obtained with these forms of energy can be explained by the differences in the depth of penetration, the most important determinant being the thickness of the subcutaneous fat and musculature covering the area being treated.


Title Comparing elastographic strain images with modulus images obtained using nanoindentation: Preliminary results using phantoms and tissue samples.
Author Srinivasan S, Krouskop T, Ophir J.
Journal Ultrasound Med Biol
Volume
Year 2004
Abstract Conventional elastography involves quasistatic mechanical compression (external or internal) of the tissue under ultrasonic insonification to obtain radiofrequency (RF) A-lines before and after compression. Cross-correlation of the pre- and postcompression A-lines results in displacement images with axial gradients that produce the strain images (strain elastograms). Though the strain elastograms show structural similarities to the modulus images, they are not related in a simple way to the modulus images because these trains depend on both modulus and geometry of the materials being deformed. Therefore, a quantification of the similarities between the strain and modulus images may enhance the interpretation confidence of strain elastograms in depicting tissue structure. To demonstrate similarities between modulus images and strain elastograms, a feasibility study of using nanoindentation to obtain modulus images of thin slices of tissue and tissue-mimicking phantoms (agar-gelatin mixtures) was performed first, with encouraging results. This was followed by a comparison of modulus images and strain elastograms obtained from the same sample slices. The experimental results indicated that, under certain experimental conditions, it is feasible to perform quantitative comparisons between strain images (using elastography) and modulus images. A good visual, as well as quantitative, correspondence between structures in the modulus and strain images could be obtained at a 3-mm scale.


Title Comparison of acoustic fields radiated from piezoceramic and piezocomposite focused radiators.
Author Cathignol D.
Journal J Acoust Soc Am
Volume
Year 1999
Abstract The acoustic field radiated from piezoelectric transducers is usually predicted supposing that the transducer vibrates in thickness mode. However, different reports have shown that not only thickness vibrations were excited, but also plate waves. These waves are responsible for discrepancy between the experimental acoustic fields and those predicted by the Rayleigh integral. It could be supposed that the plate waves are strongly attenuated in piezocomposite materials, as mechanical cross-talk between neighboring elements of the composite structure is fairly weak. A similar effect could be achieved in piezoceramic material by employing a heavy backing, which partially damps the plate waves. These opportunities of plate wave damping are investigated in the present paper. Three transducers are studied, which have identical geometrical characteristics, but are made from different materials. The plate waves in these transducers are indirectly compared by measuring corresponding ultrasound fields and comparing them with theoretically predicted field. It is shown that plate wave patterns are strongly material dependent and that it is only for piezocomposite sources (even when highly focused) that Rayleigh integral modeling can accurately predict the pressure field distribution. © 1999 Acoustical Society of America.


Title Comparison of algorithms for estimating ultrasound attenuation when predicting cervical remodelling in a rat model.
Author Bigelow TA, Labyed Y, mcfarlin BL, Gupta ES, O'Brien WD Jr.
Journal IEEE Int Ultrasonics Symp Proc
Volume
Year 2011
Abstract The future of biomedical imaging involves obtaining quantitative diagnostic information about tissue structure and function rather than just relying on qualitative structural assessments. Ultrasound attenuation or loss of signal within tissue can be used to quantify micro-structural changes in the tissue consistent with cervical remodeling. In order to obtain the best estimates, the algorithms used to estimate ultrasound attenuation (spectral log difference method,spectral difference method, and hybrid method) need to be optimized and compared. In this study, the effects of the inhomogeneities within the ROI on the accuracy of the 3 algorithms were studied, and the optimal ROI size (number of independent echoes laterally and number of pulse lengths axially) was quantified for each method. The conclusions were then validated by analyzing an ultrasound image of a pregnant rat cervix from a custom-made high-frequency ultrasound imaging system.


Title Comparison of an acousto-optic and a radiation force method of measuring ultrasonic power.
Author Haran ME, Cook BD, Stewart HF.
Journal J Acoust Soc Am
Volume
Year 1975
Abstract During the interim period while nationally acceptable methods of measurement of referential standards for ultrasonic power are being developed, comparisons are needed among measurement techniques currently used. This is particularly necessary for determining the acoustic power from ultrasonic medical devices. Such a comparison was made between an optical and a radiation force technique to measure the ultrasonic power output of a 1-MHz 1-in.-diameter PZT crystal from 70 mW to 2.3 W total acoustic power. The optical technique flows the theory of Raman and Nath, assaying the diffraction of monochromatic light by ultrasound. In addition, a correction factor is introduced into the calculation of the phase retardation parameter and eliminates the need to determine the pathlength of the light through the sound. The radiation force technique relates the change of position of an air-backed, self-centering, reflecting float to the ultrasonic power. A linear regression analysis between the square of the voltage applied to the crystal and the measured power of each method was used. For a 99% confidence level, there is no statistical difference between the measurements over the range of power investigated, although the variance of the optical measurements was significantly lower than that of the radiation force.


Title Comparison of biparietal diameter and femur length in the third trimester: Effects of gestational age and variation in fetal growth.
Author Wolfson RN Peisner DB Chik LL Sokol RJ.
Journal J Ultrasound Med
Volume
Year 1986
Abstract A multiple regression-based statistical model capable of quantitatively comparing two or more sonographic parameters for the effects of gestational age, variation in fetal growth and error in sonographic measurement is presented and then used to compare the biparietal diameter and femur length as estimators of gestational age in late pregnancy. A total of 311 patients were studied between 24 and 42 weeks' gestation. Variation in fetal growth was expressed as the birth weight percentile for gestational age. Biparietal diameter and femur length correlated equally well with gestational age. However, the biparietal diameter was more than twice as sensitive as the femur length to variation in fetal growth. Femur length had a larger error associated with its measurement. These results suggest that the biparietal diameter and femur length in late pregnancy are equal estimators of gestational age; that the femur length is a more stable estimator of gestational age when fetal growth deviates from normal; and that the femur length is technically more difficult to obtain.


Title Comparison of diastolic filling models and their fit to transmitral Doppler contours.
Author Nudelman S, Manson AL, Hall AF, Kovacs SJ Jr.
Journal Ultrasound Med Biol
Volume
Year 1995
Abstract Anatomic/physiologic and kinematic mathematical models of diastolic filling which employ (lumped) parameters of diastolic function have been used to predict or characterize transmitral flow. The ability to determine model parameters from clinical transmitral flow, the Doppler velocity profile (DVP), is equivalent to solving the "inverse problem" of diastole. Systematic model-to-model and model-to-data comparison has never been carried out, in part due to the requirement that DVPs be digitized by hand. We developed, tested and verified a computerized method of DVP acquisition and reproduction, and carried out numerical determination of model-to-model and model-to-data goodness-of-fit. The transmitral flow velocity of two anatomic/physiologic models and one kinematic model were compared. Each model's ability to fit computer-acquired and reproduced transmitral DVPs was assessed. Results indicate that transmitral flow velocities generated by the three models are 'graphically indistinguishable and are able to fit the E-wave of clinical DVPs with comparable mean-square errors. Nonunique invertibility of the anatomic/physiologic models was verified, i.e., multiple sets of model parameters could be found that fit a single DVP with comparable mean-square error. The kinematic formulation permitted automated, unique, model-parameter determination, solving the "inverse problem" for the Doppler E-wave. We conclude that automated, quantitative characterization of clinical Doppler E-wave contours using this method is feasible. The relation of kinematic parameters to physiologic variables is a subject of current investigation.


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