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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 310 out of 330
| Title |
Ultrasound image segmentation with shape priors: Application to automatic cattle rib-eye area estimation. |
| Author |
Arias P, Pini A, Sanguinetti, Sprechmann P, Cancela P, Fernández A, Gómez A, Randall G. |
| Journal |
IEEE Trans Image Process |
| Volume |
|
| Year |
2007 |
| Abstract |
Automatic ultrasound (US) image segmentation is a difficult task due to the quantity of noise present in the images and the lack of information in several zones produced by the acquisition conditions. In this paper, we propose a method that combines shape priors and image information to achieve this task. In particular, we introduce knowledge about the rib-eye shape using a set of images manually segmented by experts. A method is proposed for the automatic segmentation of new samples in which a closed curve is fitted taking into account both the US image information and the geodesic distance between the evolving curve and the estimated mean rib-eye shape in a shape space. This method can be used to solve similar problems that arise when dealing with US images in other fields. The method was successfully tested over a database composed of 610 US images, for which we have the manual segmentations of two experts. |
| Title |
Ultrasound images corrected for refraction and attenuation: A comparison of new high resolution methods. |
| Author |
Johnson SA, Grenleaf JF, Rajagopalan B, Bahn RC. |
| Journal |
Proc Conf Comput Aided Tomogr Ultrason Med - Haifa |
| Volume |
|
| Year |
1978 |
| Abstract |
A reflection technique using focused or synthetically focused ultra-sound energy has been developed which permits the synthesis or reconstruction of images of reflection and acoustic impedance. This technique uses digitally sampled reflection and transmission data obtained from an aperture which enclosed or circumscribes the subject of study. Control of the waveform of the transmitted signal is an important feature. These and other new high resolution imaging methods are compared with older clinical techniques. The extension of waveform control to linear array imaging is discussed and example images are presented. The effect of apodizing linear arrays is demonstrated by sample images. The mixing of image point response functions for two points due to nonlinear data collection or compression is demonstrated. Images produced from a new iterative data inversion process are presented. Potential diagnostic medical applications are discussed. |
| Title |
Ultrasound images of human fetal development. |
| Author |
Birnholz JC. |
| Journal |
Am Sci |
| Volume |
|
| Year |
1984 |
| Abstract |
No abstract available. |
| Title |
Ultrasound imaging : an overview. |
| Author |
karrer HE, Dickey AM. |
| Journal |
Hewlett-Packard Journal |
| Volume |
|
| Year |
1983 |
| Abstract |
No abstract available. |
| Title |
Ultrasound imaging in operative neurosurgery. |
| Author |
Koivukangas J. |
| Journal |
Thesis(PhD): Univ of Oulu |
| Volume |
|
| Year |
1984 |
| Abstract |
no abstract available. |
| Title |
Ultrasound imaging in operative neurosurgery. |
| Author |
Koivukangas J. |
| Journal |
Thesis(PhD): Univ of oulu |
| Volume |
|
| Year |
1984 |
| Abstract |
No Abstract Available. |
| Title |
Ultrasound imaging of apoptosis in tumor response: novel preclinical monitoring of photodynamic therapy effects. |
| Author |
Banihashemi B, Vlad R, Debeljevic B, Giles A, Kolios MC, Czarnota GJ. |
| Journal |
Cancer Res |
| Volume |
|
| Year |
2008 |
| Abstract |
High-frequency ultrasound is a novel method to detect apoptotic cell death based on changes in cell morphology that cause alterations in the viscoelastic and, consequently, the acoustic properties of cell ensembles and tissues. In this study, we evaluated the first preclinical tumor-based use of high-frequency ultrasound spectroscopy to noninvasively monitor tumor treatment by following xenograft malignant melanoma tumor responses to photodynamic therapy (PDT) in vivo. We observed a time-dependant increase in ultrasound backscatter variables after treatment. The observed increases in spectroscopic variables correlated with morphologic findings, indicating increases in apoptotic cell death, which peaked at 24 hours after PDT. We analyzed the changes in spectral slope and backscatter in relation to apoptosis and histologic variations in cell nuclear size. Changes in spectral slope strongly correlated with the changes in mean nuclear size over time, associated with apoptosis, after PDT (P < 0.05). At 48 hours, a decrease in ultrasound backscatter was observed, which could be explained by an increase in cell nuclear degradation. In summary, we show that high-frequency ultrasound spectroscopic variables can be used noninvasively to monitor response after treatment in a preclinical tumor cancer model. These findings provide a foundation for future investigations regarding the use of ultrasound to monitor and aid the customization of treatments noninvasively based on responses to specific interventions. |
| Title |
Ultrasound imaging of apoptosis: High-resolution non-invasive monitoring of programmed cell death in vitro, in situ and in vivo. |
| Author |
Czarnota GJ, Kolios MC, Abraham J, Portnoy M, Ottensmeyer FP, Hunt JW, Sherar MD. |
| Journal |
Br J Cancer |
| Volume |
|
| Year |
1999 |
| Abstract |
A new non-invasive method for monitoring apoptosis has been developed using high frequency (40 MHz) ultrasound imaging. Conventional ultrasound backscatter imaging techniques were used to observe apoptosis occurring in response to anticancer agents in cells in vitro, in tissues ex vivo and in live animals. The mechanism behind this ultrasonic detection was identified experimentally to be the subcellular nuclear changes, condensation followed by fragmentation, that cells undergo during apoptosis. These changes dramatically increase the high frequency ultrasound scattering efficiency of apoptotic cells over normal cells (25- to 50-fold change in intensity). The result is that areas of tissue undergoing apoptosis become much brighter in comparison to surrounding viable tissues. The results provide a framework for the possibility of using high frequency ultrasound imaging in the future to non-invasively monitor the effects of chemotherapeutic agents and other anticancer treatments in experimental animal systems and in patients. |
| Title |
Ultrasound imaging using diffraction tomography in a cylindrical geometry. |
| Author |
Chambers DH, Littrup P. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
2002 |
| Abstract |
Tomographic images of tissue phantoms and a sample of breast tissue have been produced from an acoustic synthetic array system for frequencies near 500 kHz. The images for sound speed and attenuation show millimeter resolution and demonstrate the feasibility of obtaining high-resolution tomographic images with frequencies that can deeply penetrate tissue. The image reconstruction method is based on the Born approximation to acoustic scattering and is a simplified version of a method previously used by Andre (Andre, et. al., Int. J. Imaging Systems and Technology, Vol 8, No. 1, 1997) for a circular acoustic array system. The images have comparable resolution to conventional ultrasound images at much higher frequencies (3-5 MHz) but with lower speckle noise. This shows the potential of low frequency, deeply penetrating, ultrasound for high-resolution quantitative imaging. |
| Title |
Ultrasound imaging using variations of the iterative born technique. |
| Author |
Liu L, Zhang X, Broschat SL. |
| Journal |
IEEE Trans UFFC |
| Volume |
|
| Year |
1999 |
| Abstract |
The iterative Born method is an inverse technique that has been used successfully in ultrasound imaging. However, the calculation cost of the standard iterative Born method is high, and parallel computation is limited to the forward problem. In this work, two methods are introduced to increase the rate of convergence of the iterative Born algorithm. These methods are tested on three different objects. The results are promising, with both algorithms giving accurate results at lower computational cost. The first method, referred to as the coarse resolution initial value (CRIV) method, uses the iterative Born algorithm for a coarse grid to quickly estimate the initial value of the object to be reconstructed. From this initial value, the final image is obtained for a finer grid with additional iterations. The cost of this method is 40% less than that of the iterative Born technique. The second method, the quadriphase source (QS) method, simultaneously uses four single sources, and object reconstruction for each is performed in parallel; the reconstruction results for all four sources then are averaged to abtain the final image. The cost of this method is 20% less than that of the standard iterative Born method. When the object to be reconstructed is of low contrast and/or has a small phase shift, the QS method is very promising because parallel computation can be used to solve both the forward and inverse problems. However, the QS method fails for high contrast objects. |
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