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BRL Abstracts Database |
Your search for ultrasound produced 3296 results. Page 48 out of 330
Title |
Automated three-dimensional ultrasound breast scanning in the compressed mammography position. |
Author |
Dines KA, Kelly-Fry E, Romilly-Haper AP. |
Journal |
J Ultrasound Med |
Volume |
|
Year |
1999 |
Abstract |
No abstract available. |
Title |
Automated three-dimensional ultrasound breast scanning in the craniocaudal mammography position. |
Author |
Dines KA, Kelly-Fry E, Romilly-Harper AP. |
Journal |
Proc Ninth Int Cong Ultrason Ex Breast |
Volume |
|
Year |
1995 |
Abstract |
None |
Title |
Automatic attenuation compensation for ultrasonic imaging. |
Author |
Hughes DI, Duck FA. |
Journal |
Ultrasound Med Biol |
Volume |
|
Year |
1997 |
Abstract |
A new method has been developed for the automatic correction for attenuation in ultrasonic pulse-echo imaging. By assuming that a specified relationship holds between local attenuation and local backscatter throughout each pulse-echo signal, a gain factor may be calculated that more appropriately compensates for attenuation at every depth. The rationale depends on the observation that, broadly speaking, materials that backscatter strongly also attenuate strongly. The new method has been evaluated by postprocessing clinical B-scans following video frame capture. The images formed demonstrated the success of the algorithm in imaging homogeneous tissues at a constant grey level, irrespective of variations in the attenuation of overlying tissue. For example, the fetal lung was imaged uniformly irrespective of the presence of rib or spine, and prostatic tissue was imaged uniformly through a partial bladder window. Spatial resolution and speckle patterns are retained. The method is suitable for real-time application. |
Title |
Automatic detection of ultrasound contrast microbubble shell rupture. |
Author |
Ammi AY, Bridal L, Mamou J, Wang GI, O'Brien WD Jr. |
Journal |
Proc Ultrason Symp IEEE |
Volume |
|
Year |
2006 |
Abstract |
Characterizing occurrence of ultrasound contrast agent (UCA) microbubble destruction is important for development of functional and therapeutic applications. Previously [Ammi, et. al., 2006], it was demonstrated that post-excitation acoustic emissions detected with passive cavitation detection (PCD) result from inertial cavitation (IC) of UCA after shell rupture. That work relied on time-consuming visual inspection of PCD data to identify IC signals and characterized only minimum rarefactional pressure thresholds for rupture of a single Optisontrade microbubble in the sampled population. This work introduces an algorithm for automatic detection of IC signals. The algorithm was applied to the 71424 waveforms in the PCD data set. At each incident frequency (0.9, 2.8 or 4.6 MHz) and pulse duration (3, 5 or 7 cycles) combination, ruptured microbubble occurrence with incident peak rarefactional pressure (PRP) was well described by a logistic regression curve with an inflection point near 50% occurrence and a plateau at 100%. With a 5-cycle pulse duration at 0.9, 2.8 and 4.6 MHz the incident PRPs leading to 5% microbubble rupture were 0.66, 0.83 and 1.1 MPa; and 1.1, 1.6 and 2.5 MPa for 50%. This automatic algorithm combined with the PCD approach provides a practical tool for the characterization of UCA destruction occurrence across a significant range of incident PRPs. |
Title |
Automatic midline echoencephalography. |
Author |
White DN. |
Journal |
Proc Int Symp Recent Adv Ultrasound Diagn - Dubrovnik |
Volume |
|
Year |
1977 |
Abstract |
No abstract available. |
Title |
Average dose absorbed by biological specimens in a diffuse ultrasonic exposure field. |
Author |
Christman CL. |
Journal |
J Acoust Soc Am |
Volume |
|
Year |
1981 |
Abstract |
A reverberation method has been investigated for determining the total acoustic energy absorbed by biological specimens exposed to ultrasound at clinical frequencies. The specimen is exposed to a diffuse ultrasonic field created in a small water-filled tank by a 1.0-MHz carrier signal, frequency modulated with white noise. Measurements of the total acoustic input power and the decay rate, both with and without the specimen, are used to determine average dose. Three different methods for measuring input power and one method for measuring decay rate have been investigated. Numerous performance tests have been used to assign uncertainty limits for the measurement of average dose. This new reverberation exposure method has been compared to the more traditional free-field exposure method by recording the temperature rise within anesthetized mice for both methods. These results will be used to estimate the exposure conditions for each method needed to produce the same average temperature rise within an animal.
|
Title |
Average velocity of ultrasound in the human female breast. |
Author |
Kossoff G, Kelly-Fry E, Jellins J. |
Journal |
J Acoust Soc Am |
Volume |
|
Year |
1973 |
Abstract |
A technique for measuring the in vivo average velocity of ultrasound in the human female breast was developed and applied to determine the range of such values in the breast of normal subjects in the approximate age ranges 20 to 80 years and in subjects with selected breast pathologies. Reasonable correlation of the velocity values with breast tissue type, as determined by x ray (mammography), was obtained, indicating that ultrasonic velocity data provide useful information on the main tissue constituents in the breast and that this technique should allow safe, long-term study of changes that may occur in the composition of such tissues. |
Title |
Average velocity of ultrasound in the human female breast. |
Author |
Kossoff G, Kelly-Fry E, Jellins J. |
Journal |
Ultrasound Symp |
Volume |
|
Year |
1973 |
Abstract |
No abstract available. |
Title |
Axial resolution in elastography. |
Author |
Righetti R, Ophir J, Ktonas P. |
Journal |
Ultrasound Med Biol |
Volume |
|
Year |
2002 |
Abstract |
The limits and trade-offs of the axial resolution in elastography were investigated using a controlled simulation study. The axial resolution in elastography was estimated as the distance between the full widths at half-maximum of the strain profiles of two equally stiff lesions embedded in a softer homogenous background. The results show that the upper bound of the axial resolution in elastography is controlled by the physical wave parameters of the ultrasound (US) system used to acquire the data (transducer center frequency and bandwidth). However, an inappropriate choice of the parameters used to process the US data (cross-correlation window length and shift between consecutive windows) may compromise the best resolution attainable. The measured elastographic axial resolution was found to be on the order of the ultrasonic wavelength. |
Title |
Axial stress distributions between coaxial compressors in elastography: An analytical model. |
Author |
Ponnekanti H, Ophir J, Cespedes I. |
Journal |
Ultrasound Med Biol |
Volume |
|
Year |
1992 |
Abstract |
We describe an analytical model to study the behavior of stress along the compression axis for different configurations of opposing circular compressors as applied to elastography. The method is based on a hypothesis that the axial stress at any point on the axis is the superposition of the individual components of the stresses dervied from the boundary conditions at either end. The determination of the axial stress behavior according to the model permits the correction of certain elastograms for depth-dependent stress. Experimental results have been presented to corroborate the model. |
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