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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 147 out of 330
| Title |
In situ exposimetry: The ovarian ultrasound examination. |
| Author |
Siddiqi TA, O'Brien WD Jr, Meyer RA, Sullivan JM, Miodovnik M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1991 |
| Abstract |
We have constructed a specialized in vivo exposimetry system and developed and tested customized software using specially fabricated hydrophones. We placed the hydrophones in the lateral vaginal fornix as close to the ovary as possible (usually 1–2 cm from the ovary) and determined selected first-order and second-order ultrasonic field quantities during a routine ultrasound examination of the ovary. Our sonographic measurements yielded mean ultrasound beam path distances of 7.6 cm. (n =18) in the presence of a distended bladder and 7.0 cm. (n = 25) in the presence of an empty bladder with an average group insertion loss of 6.2 dB and 7.3 dB, respectively. Using a Fixed Attenuation Model, the tissue attenuation coefficient value was 2.98 dB/MHz; whereas for the Overlying Tissue Model the value was 0.72 dB/cm-MHz. These data are both specific and unique in that they have been systematically obtained in situ. |
| Title |
In situ human obstetrical ultrasound exposimetry: Estimates of derating factors for each of three different tissue models. |
| Author |
Siddiqi TA, O'Brien WD Jr, Meyer RA, Sullivan JM, Miodovnik M. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1995 |
| Abstract |
A specialized in vivo exposimetry system was developed to acquire transabdominal in situ ultrasound exposure quantities in obstetric patients. Under surgical conditions, the sterilized 7-element calibrated linear array hydrophone was introduced into the uterus under direct ultrasound guidance and placed in direct contact with the products of conception, usually in the saggital midplane of the uterine cavity. Twenty-five patients with empty bladders and 10 patients with full bladders were studied at gestational ages between 7 and 20 weeks. In the empty bladder condition, the sound beam traversed the anterior abdominal wall, uterus, amniotic fluid and fetal parts and in the full bladder condition, the sound beam also traversed the fluid-filled bladder. Each study was conducted with a 3 MHz, mechanical sector transducer in combination with an ATL Ultramark 4 diagnostic ultrasound imaging system. Calibration data were recorded after completion of each in vivo patient study. The acquired exposimetry data from the 35 obstetric patients were used to evaluate the appropriateness of three tissue attenuation models, viz., fixed path, homogeneous and overlying. All three tissue models yield a mean attenuation coefficient value of about a factor of 3 to 4 greater than their respective minimum values. In the case of the overlying and homogeneous tissue models, there was a statistically significant correlation between their calculated attenuation coefficients and total distance for the combined data set whereas there was no such dependency for the calculated fixed-path tissue model. In summary, any one of the three tissue models may be used to estimate in utero acoustic quantities during the first and second trimesters of human pregnancy based on this study. |
| Title |
In utero exposure to diagnostic ultrasound: a 6-year follow-up. |
| Author |
Lyons EA, Dyke C, Toms M, Cheang M. |
| Journal |
Radiology |
| Volume |
|
| Year |
1988 |
| Abstract |
A 6-year follow-up study of height and weight was conducted between 1975 and 1983 in a total of 149 sibling pairs of the same sex, one of whom had been exposed to diagnostic ultrasound in utero. The data were analyzed for the entire sample group, as well as for subgroups defined by sex, gestational age at delivery, birth order, and gestational age at time of first exposure to ultrasound. No statistically significant differences of head circumference at birth or of height and weight between birth and 6 years of age were found between ultrasound-exposed and unexposed siblings. In our sample population, exposure of fetuses to ultrasound did not significantly affect growth in childhood up to 6 years of age. |
| Title |
In utero measurement of ultrasonically induced fetal mouse temperature increases. |
| Author |
Carnes KI, Drewniak JL, Dunn F. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1991 |
| Abstract |
The temperature increase in the murine fetus, exposed in vivo to 1 MHz ultrasound in the spatial-peak temporal-average intensity range 0.5 to 10 W/cm2 for durations of 30 to 400 s, was determined with implanted thermocouples at 9, 12 and 15 days of gestation by a method that preserved the normal uterine environment. The results show that the temperature increase is related approximately linearly to the energy flux It, where I is the acoustic intensity and t is the exposure duration. The temperature increase was observed to be nearly the same for the 9- and 12-day fetuses but less for day-15 specimens, possibly due to the smaller size in early gestation and increased vascularization in later gestation. The results are compared with calculations based on a model of a pair of nested parallelpipeds for which the properties of the outer body remain unchanged, the dimensions and absorption coefficient of the inner body increase with gestational age and the perfusion constant varies with gestational age. |
| Title |
In vitro and in vivo imaging of peptide-encapsulated polymer nanoparticles for cancer biomarker activated drug delivery |
| Author |
Kulsharova GK, Lee MB, Cheng F, Haque M, Choi H, Kim K, O'Brien WD Jr, Liu GL |
| Journal |
IEEE Trans Nanobiosci |
| Volume |
|
| Year |
2013 |
| Abstract |
Gelatin nanoparticles coated with Cathepsin D-specific peptides were developed as a vehicle for the targeted delivery of the cancer drug doxorubicin (DOX) to treat breast malignancy.Cathepsin D, a breast cancer cell secretion enzyme, triggered the release of DOX by digesting the protective peptide-coating layer of nanoparticles. Fabricated nanoparticles were successfully detected with ultrasound imaging in both in vitro conditions and in vivo mouse cancer models. Cell viability experiments were conducted to determine the efficacy of iomarker activation specific to breast cancer cell lines. These experimental results were compared with the outcome of a viability experiment conducted on noncancerous cells. Viability decreased in human MCF7 mammary adenocarcinoma and mouse 4T1 mammary carcinoma cells, while that of noncancerous 3T3 fibroblast cells remained unaffected. Next, a real-time video of nanoparticle flow in mouse models was obtained using in vivo ultrasound imaging. The fluorescent profile of DOX was used as a means to examine nanoparticle localization in vivo . Results show the distribution of nanoparticles concentrated primarily within bladder and tumor sites of subject mice bodies. These findings support the use of biomarker coated nanoparticles in target specific therapy for breast cancer treatment. |
| Title |
In vitro calculation of flow by use of contrast ultrasonography. |
| Author |
Heidenreich PA, Wiencek JG, Zaroff JG, Aronson S, Segil LJ, Harper PV, Feinstein SB. |
| Journal |
J Am Soc Echocardiogr |
| Volume |
|
| Year |
1993 |
| Abstract |
Contrast echocardiography has been used for qualitative assessment of cardiac function, and its.potential for quantitative assessment of blood flow is being explored. With the development of an.ultrasound contrast agent capable of passage through the microcirculation, a mathematical model.based on classic dye dilution theory, and a digital ultrasound acquisition system, absolute.quantitation of myocardial perfusion may be feasible. This study validates the mathematical.model in a simple in vitro tube system. Flow was delivered at variable rates through an in vitro.tube system while a longitudinal section was imaged with a modified commercial ultrasound.scanner. Albunex contrast agent was injected, and videointensity data were captured and.analyzed off line. Time-intensity curves were generated, and flow was calculated by use of a.mathematical model derived from classic dye dilution mathematics. For 39 different flow rates,.ranging for 9.2 to 110 ml/seconds, a correlation coefficient of r = 0.928 (p < 0.001) with a slope.of 0.97 was calculated. We conclude that (1) contrast ultrasonography is capable of quantitative.determination of flow in an in vitro system, and (2) a mathematical model based on dye dilution.theory can be used to calculate flow with accuracy and precision. |
| Title |
In vitro classification of gallstones by quantitative echography. |
| Author |
Goedegebure A, van der Steen AF, Thijssen JM. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1992 |
| Abstract |
Gallstones (n = 20) were classified by dual energy Computer Tomography (CT) into three main classes: pure cholesterol stones (I), combination stones (II) and calcium stones (III). Further subclassification was possible by using morphological criteria. The acoustic measurements that were performed were measurements of the velocity of sound, the attenuation coefficient slope with frequency and intercept at 4.5 MHz, the attenuation coefficient slope per unit of time, the backscattering characteristics, and the appearance of B-mode echograms. The velocity of sound in calcium stones (c = 1695 +/- 107 m/s) was distinctly lower than in those containing some cholesterol (c > 2000 m/s). The attenuation coefficient slope ranged from 4.3 to 16.2 dB/cm MHz, the 4.5 MHz intercept from 21 to 66.2 dB/cm. The lowest values were found for the pure cholesterol stones (class IA), the highest values for subclass IIB (combination stones with shell).The attenuation coefficient slope per unit of time was distinctly lower (< 0.50 dB/microseconds MHz) for the cholesterol stones than for the combination and calcium stones (>0.64.dB/microseconds MHz). The backscattering spectrum was approximated by a straight line fit, and the slope for the cholesterol stones was lower than for the combination and calcium stones.(<0.75 dB/MHz vs. >1.0 dB/MHz, respectively). The latter two parameters were assessed by in vivo applicable methods. The front echo level was found to be more than 5 dB higher for class IIB as compared to the other classes, while the spectral backscatter level at 4.5 MHz was considerably higher for both classes IIB and III. The B-mode echograms showed that a strong front echo in combination with a strong attenuation of the remaining echo signals was mainly found for stones of classes IIB and III. A significant difference between the group of stones that are suitable for lithotripsy and dissolution treatment (classes IA, IB and IIA) and the nontreatable calcium-containing stones (classes IIB and III) was found for the velocity of sound (p <0.01), the attenuation coefficient slope per time unit (p <0.10), the slope of the backscattering spectrum (p <0.05) and the 4.5 MHz intercept (p <0.01). B-mode classification yielded no complete distinction of these two groups of stones. It can be concluded that in vivo assessment of quantitative characteristics (front reflection, backscattering characteristics, attenuation coefficient slope per unit of time) in combination with the B-mode characteristics might be useful for in vivo gallstone classification. |
| Title |
In vitro clumping of platelets exposed to low intensity ultrasound. |
| Author |
Miller DL, Nyborg WL, Whitcomb CC. |
| Journal |
Proc Twenty-second Annu Meet AIUM |
| Volume |
|
| Year |
1977 |
| Abstract |
No abstract available. |
| Title |
In Vitro Clumping of Platelets Exposed to Low Intensity Ultrasound. |
| Author |
Miller DL, Nyborg WL, Whitcomb CC. |
| Journal |
Ultrasound Med |
| Volume |
|
| Year |
1978 |
| Abstract |
No abstract available. |
| Title |
In vitro detection of cavitation induced by a diagnostic ultrasound system. |
| Author |
Holland CK, Roy RA, Apfel RE, Crum LA. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1992 |
| Abstract |
Experiments were performed in vitro to investigate the possibility of transient cavitation from short-pulse, diagnostic ultrasound under conditions comparable to clinical ultrasound examinations. An acoustic backscattering technique that utilizes 30-MHz pulsed ultrasound was employed to probe the potential of cavitation production by a clinical ultrasound scanner, specifically a Hewlett-Packard 77020A. Two calibrated, phased-array HP imaging transducers with 2.5- and 5.0- MHz operating frequencies were driven in M-mode (single cycle) and Doppler mode (4 cycles) by the HP imaging system. Hydrophonic polystyrene spheres with an average diameter of 0.245 ?m and Albunex, an echo contrast agent consisting of 1- to 10-?m bubbles with a human serum albumen coating, served as potential cavitation nuclei. Cavitation was detected in the water with polystyrene spheres at 2.5 MHz in both M-mode and Doppler mode at a peak negative acoustic pressure of 1.1 Mpa or greater. Insonification at 5.0 MHz in either mode did not produce a detectable amount of cavitation, even with peak negative pressures as high as 1.2 Mpa. Also, cavitation was not detected in water with the Albunex spheres at either frequency. |
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