Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
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William D. O'Brien, Jr. publications:

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Title Effect of mode conversion on ultrasonic heating at tissue interfaces.
Author Haken BA, Frizzell LA, Carstensen EL.
Journal Proc Ultrason Symp IEEE
Volume
Year 1992
Abstract A number of investigators have observed localized heating by ultrasound beams near impedance discontinuities within tissues. It has been suggested that mode conversion to shear waves at impedance discontinuities and subsequent absorption of these waves in a very small distance was the explanation for this heating. A mathematical model for mode conversion at a plane interface between two viscoelastic media is presented. Longitudinal and shear properties are used to calculate the amount of mode conversion that occurs at muscle-air and muscle-bone interfaces. Shear waves in bone are found to be an important source of heating, but shear waves in the muscle provide a negligible effect on heating at the interface.


Title Effect of mode conversion on ultrasonic heating at tissue interfaces.
Author Haken BA.
Journal Thesis(BS): Univ of Illinois
Volume
Year 1992
Abstract A number of investigators have observed localized heating by ultrasound near impedence discontinuities within tissues. It has been suggested that mode conversion to shear waves at impedence discontinuities and subsequent absorption of these waves in a very small distance were the explainations for this heating. A mathematical model for mode conversion at a plane interface between two viscoelastic media is presented. Longtiudinal and shear properties are used to calculate the amount of mode conversion that occurs at muscle-bone and muscle-air interfaces. Shear waves in bone are found to be an important source of heating, but shear waves in the muscle provide a negligible effect on heating at the interface.


Title Effect of overpressure and pulse repetition frequency on cavitation in shock wave lithotripsy.
Author Sapozhnikov OA Khokhlova VA Bailey MR Williams JC Jr McAteer JA Cleveland RO Crum LA.
Journal J Acoust Soc Am
Volume
Year 2002
Abstract Cavitation appears to contribute to tissue injury in lithotripsy. Reports have shown that increasing pulse repetition frequency [(PRF) 0.5-100 Hz] increases tissue damage and increasing static pressure (1-3 bar) reduces cell damage without decreasing stone comminution. Our hypothesis is that overpressure or slow PRF causes unstabilized bubbles produced by one shock pulse to dissolve before they nucleate cavitation by subsequent shock pulses. The effects of PRF and overpressure on bubble dynamics and lifetimes were studied experimentally with passive cavitation detection, high-speed photography, and B-mode ultrasound and theoretically. Overpressure significantly reduced calculated (100-2 s) and measured (55-0.5 s) bubble lifetimes. At 1.5 bar static pressure, a dense bubble cluster was measured with clinically high PRF (2-3 Hz) and a sparse cluster with clinically low PRF (0.5-1 Hz), indicating bubble lifetimes of 0.5-1 s, consistent with calculations. In contrast to cavitation in water, high-speed photography showed that overpressure did not suppress cavitation of bubbles stabilized on a cracked surface. These results suggest that a judicious use of overpressure and PRF in lithotripsy could reduce cavitation damage of tissue while maintaining cavitation comminution of stones.


Title Effect of phase errors on field patterns generated by an ultrasound phased-array hyperthermia applicator.
Author Wang H, Ebbini E, Cain CA.
Journal IEEE Trans UFFC
Volume
Year 1991
Abstract The effect of phase quantization errors and Gaussian distributed random phase errors on field patterns synthesized by a rectangular ultrasound phased array hyperthermia applicator is studied. The parameters defined show that, over the range of four-bit to one-bit quantization, the simulated, patterns degrade with increasing phase errors. However, the overall shape and position of the foci remain unchanged. Simulation results show that, even with one-bit phase quantization, or with a Gaussian distributed random phase error of standard deviation of about 52 degrees , the applicator can still produce useful, if not particularly clean, power deposition patterns. Thus, the power deposition patterns are remarkably stable tolerating quite large phase error levels. This suggests that the power deposition patterns inside the body may be relatively insensitive to phase errors due to tissue inhomogeneities.


Title Effect of prenatal exposure to diagnostic.ultrasound on the development of mice.
Author Hande MP, Devi PU.
Journal Radiat Res
Volume
Year 1992
Abstract Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz,.approximately 65 mW) for 10 min on Day 3.5 (preimplantation period), 6.5.(early organogenesis period), or 11.5 (late organogenesis period) of gestation..Sham-exposed controls were maintained for comparison. Exposed as well as.control fetuses were dissected out on the 18th day of gestation, and changes in.total mortality, body weight, body length, head length, brain weight, sex ratio,.and microphthalmia were recorded. Exposure on Day 3.5 of gestation resulted in.a small increase in the resorption rate and a significant reduction in fetal body.weight. A low fetal weight and an increase in the number of growth-retarded.fetuses were produced by exposure on Day 6.5 postcoitus. A statistically.nonsignificant increase in the incidence of microphthalmia was induced in fetuses.exposed on Day 6.5 or Day 11.5 of gestation. These results indicate that.ultrasound may have some adverse effects on the mouse embryos depending on.the developmental stage at which the exposure occurred. .


Title Effect of prenatal ultrasound exposure on adult behavior in mice.
Author Hande MP, Devi PU, Karanth KS.
Journal Neurotoxicol Teratol
Volume
Year 1993
Abstract Pregnant Swiss mice were exposed to diagnostic levels of ultrasound (3.5 MHz, Maximum acoustic output: ISPTP = 1 W/cm2 and ISATA = 240 mW/cm2, acoustic power = 65 mW) for 10 min on days 11.5 or 14.5 postcoitus (PC). At 3 and 6 months postpartum, offspring were subjected to the following behavioral tests: bright and dark arena test for locomotor/exploratory activity and passive avoidance test for learning and memory. Anxiolytic activity and latency in learning were noticed in the ultrasound-treated animals. The effect was more pronounced in the 14.5 days PC group than in the 11.5 days PC group. But memory was not affected in the ultrasound-exposed animals. There was a nonsignificant decrease in the total locomotor activity at 6 months of age in all the exposed animals. Thus, the present data demonstrate that exposure to diagnostic ultrasound during late organogenesis period or early fetal period in mice may cause changes in postnatal behavior as evidence by selected adult offspring behavioral tests. However, any conclusive statement in this regard should await results from more detailed investigations. .


Title Effect of prenatal ultrasound screening on perinatal outcome. RADIUS Study Group.
Author Ewigman BG, Crane JP, Frigoletto FD, LeFevre ML, Bain RP, McNellis D.
Journal N Engl J Med
Volume
Year 1993
Abstract BACKGROUND. Many clinicians advocate routine ultrasound screening during pregnancy to detect congenital anomalies, multiple-gestation pregnancies, fetal growth disorders, placental abnormalities, and errors in the estimation of gestational age. However, it is not known whether the detection of these conditions through screening leads to interventions that improve perinatal outcome. METHODS. We conducted a randomized trial involving 15,151 pregnant women at low risk for perinatal problems to determine whether ultrasound screening decreased the frequency of adverse perinatal outcomes. The women randomly assigned to the ultrasound-screening group underwent one sonographic examination at 15 to 22 weeks of gestation and another at 31 to 35 weeks. The women in the control group underwent ultrasonography only for medical indications, as identified by their physicians. Adverse perinatal outcome was defined as fetal death, neonatal death, or neonatal morbidity such as intraventricular hemorrhage. RESULTS. The mean numbers of sonograms obtained per woman in the ultrasound-screening and control groups were 2.2 and 0.6, respectively. The rate of adverse perinatal outcome was 5.0 percent among the infants of the women in the ultrasound-screening group and 4.9 percent among the infants of the women in the control group (relative risk, 1.0; 95 percent confidence interval, 0.9 to 1.2; P = 0.85). The rates of preterm delivery and the distribution of birth weights were nearly identical in the two groups. The ultrasonographic detection of congenital anomalies had no effect on perinatal outcome. There were no significant differences between the groups in perinatal outcome in the subgroups of women with post-date pregnancies, multiple-gestation pregnancies, or infants who were small for gestational age. CONCLUSIONS. Screening ultrasonography did not improve perinatal outcome as compared with the selective use of ultrasonography on the basis of clinician judgment.


Title Effect of pulse polarity and energy on ultrasound-induced lung hemorrhage in adult rats.
Author Frizzell LA, Zachary JF, O'Brien WD Jr.
Journal J Acoust Soc Am
Volume
Year 2003
Abstract The objective of this study was to further assess the role of inertial cavitation in ultrasound-induced lung hemorrhage by examining the effect of pulse polarity at a common in situ (at the lung surface) peak rarefactional pressure [pr(in situ)] and at a common in situ pulse intensity integral (PIIin situ). A total of 60 rats was divided into three experimental groups of 20 animals per group and randomly exposed to pulsed ultrasound. The groups were exposed as follows: Group 1 to 0? polarity pulses (compression followed by rarefraction) at a pr(in situ) of 3.48 MPa and a PIIin situ of 4.78 Ws/m2, group 2 to 180? polarity pulses (rarefraction followed by compression) at a pr(in situ) of 3.72 MPa and a PIIin situ of 2.55 Ws/m2, and group 3 to 180? polarity pulses at a pr(in situ) of 4.97 MPa and a PIIin situ of 4.79 Ws/m2. For all experimental groups, the frequency was 2.46 MHz, the exposure duration was 240 s, the pulse repetition frequency was 2.5 kHz, and the pulse duration was 0.42 ?s. Six sham animals were also randomly distributed among the experimental animals. The lesion surface area and depth were determined for each rat as well as lesion occurrence (percentage of rats with lesions) per group. It was found that lesion occurrence and size correlated better with PIIin situ than with pr(in situ), suggesting that a mechanism other than inertial cavitation was responsible for the damage.


Title Effect of pulsed and continuous application of ultrasound on transport of ions through biologic membranes.
Author Lehmann JF, Krusen FH.
Journal Arch Phys Med Rehabil
Volume
Year 1954
Abstract No abstract available.


Title Effect of pulsed low-power ultrasound on.growing tissues. I. Developing mammalian and.insect tissue.
Author Pizzarello DJ, Vivino A, Madden B, Wolsky A, Keegan AF, Becker M.
Journal Exp Cell Biol
Volume
Year 1978
Abstract Pulsed ultrasound at 2.25 MHz was delivered by a transducer having an average power output of 1.5 mW to developing rat embryos in utero for 5 min and to larval and pupal stages of Drosophila melanogaster for 2.5 min. These exposures in some instances were lethal, in others growth inhibiting, and in still others, produced no detectable effect. Effects were dependent on stage of development at insonation.


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