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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 215 out of 330
| Title |
Real-time imaging with a new ultrasonic camera: Part I, in vitro experimental studies on transmission imaging of biological structures. |
| Author |
Marich KW, Zatz LM, Green PS, Suarez JR, Macovski A. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1975 |
| Abstract |
Results are described of in vitro biological experimentation using a new through-transmission ultrasonic camera system developed at the Stanford Research Institute. The camera system produces real-time focused, orthographic images of a 15 times 15 cm field. The in vitro studies, which.demonstrate the diagnostic potential of the new technique, include transmission images of selected excised organs such as liver, kidney, spleen, and uterus. In addition, preliminary studies evaluating ultrasonic image quality and the effect of out-of-focus structures are discussed. |
| Title |
Real-time imaging with a new ultrasonic camera: Part II, preliminary studies in normal adults. |
| Author |
Zatz LM, Marich EW, Green PS, Lipton MJ, Suarez JR, Macovski A. |
| Journal |
J Clin Ultrasound |
| Volume |
|
| Year |
1975 |
| Abstract |
A new transmission ultrasound camera system has provided focused images in real time through the abdomen of adult volunteers at average incident sound intensity levels of less than 1 mW/cm-2. The camera uses a unique acousto-mechanical lens/deflection system and a linear array of piezoelectric transducers to detect the ultrasound image. Bony structures and costal cartilages were clearly seen. The colon was regularly seen and the kidney could be outlined in several subjects. The stomach and duodenal bulb were demonstrated and peristalsis was observed using a barium contrast material. The camera has the potential of extending the use of ultrasound in clinical medicine by providing an ultrasound soft tissue imaging system analogous to an x-ray fluoroscope. The need for further clinical evaluation and research to improve the images is emphasized. |
| Title |
Real-time passive acoustic monitoring of HIFU-induced tissue damage. |
| Author |
Nandlall SD, Jackson E, Coussios CC. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2011 |
| Abstract |
Thermal ablation by high-intensity focused ultrasound (HIFU) shows great promise as a noninvasive cancer therapy. This work proposes a novel method of real-time HIFU treatment monitoring that uses the passively monitored acoustic signal emanating from the focus during HIFU exposure. We performed 212 exposures in seven freshly excised ox livers using 1.067-MHz HIFU at a 95% duty cycle for a range of insonation durations and acoustic intensities. Acoustic emissions were recorded using a 15-MHz passive detector aligned confocally and coaxially with the HIFU transducer. Lesion presence and size were ascertained by slicing the tissue in the transverse and axial focal planes post exposure. Our results demonstrate that successful formation of HIFU lesions in ex vivo ox liver is highly correlated with the presence of pronounced dips in the magnitude of the received signal at integer harmonics of the insonation frequency. A detector based on this observation predicted lesioning with >80% accuracy in regimes that were very likely to create lesions (≥60 J of energy) and had an error rate of <6% for exposures that were too short to cause lesioning (≤1 s long). The overall sensitivity and specificity of the detector were 75.6% and 74.2%, respectively. The proposed detector could therefore provide a low-cost means of effectively monitoring clinical HIFU treatments passively and in real time. |
| Title |
Real-time system for angle-independent US of blood flow in two.dimensions: initial results. |
| Author |
Bohs LN, Friemel BH, McDermott BA, Trahey GE. |
| Journal |
Radiology |
| Volume |
|
| Year |
1993 |
| Abstract |
The authors developed an ultrasound system that enables the speckle patterns produced by echoes from moving blood to be.tracked in real time. Unlike current color Doppler flow imagers, this system allows the measurement of blood velocities in any.direction within the imaging plane. The authors used this device to image flow in the human jugular vein and contrasted the.image with one obtained under similar circumstances with color Doppler flow imaging. The authors demonstrated that this.system can display in vivo lateral blood flow in real time. Further development of the system, including the incorporation of wall.filters to enhance weak blood echoes and parallel techniques to reduce data acquisition time, will allow clinical imaging of flow.with velocities of several meters per second in any direction without aliasing or dependence on the Doppler angle. |
| Title |
Real-time three-dimensional intracardiac echocardiography. |
| Author |
Light ED, Idriss SF, Wolf PD, Smith SW. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2001 |
| Abstract |
Using catheter-mounted 2-D array transducers, we have obtained real-time 3-D intracardiac ultrasound (US) images. We have constructed several transducers with 64 channels inside a 12 French catheter lumen operating at 5 MHz. The transducer configuration may be side-scanning or beveled, with respect to the long axis of the catheter lumen. We have also included six electrodes to acquire simultaneous electrocardiograms. Using an open-chest sheep model, we inserted the catheter into the cardiac chambers to study the utility of in vivo intracardiac 3-D scanning. Images obtained include a cardiac four-chamber view, mitral valve, pulmonic valve, tricuspid valve, interatrial septum, interventricular septum and ventricular volumes. We have also imaged two electrophysiological interventional devices in the right atrium, performed an in vitro ablation study, and viewed the pulmonary veins in vitro. |
| Title |
Real-time ultrasonic assessment of progressive proteoglycan depletion in articular cartilage. |
| Author |
Wang Q, Zheng YP, Quin L, Huang QH, Lam WL, Leung G, Guo X, Lu HB. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
2008 |
| Abstract |
The loss of proteoglycan (PG) is regarded as one of the early signs of osteoarthritis (OA), thus observing the progress of PG loss would be useful for the early detection of OA. In this study, high-frequency ultrasound was used to monitor and analyze the trypsin-induced progressive degeneration in articular cartilage. Full thickness cartilage-bone specimens (n = 10) prepared from normal bovine patellae were digested using 0.25% trypsin solution for different periods of time to evaluate the dynamics of the digestion process. The trypsin penetration front was observed in M-mode image, which was acquired using a nominal 50 MHz focused transducer. The transient speed of the digestion process was estimated from the image. The digestion fraction, which represents the ratio of the digestion depth to the total cartilage thickness, was estimated from ultrasound data and histology sections. With ultrasound, the digestion fraction observed in the 10 specimens ranged from 64% to 99% and was correlated to that measured by histology (R2 ≥ 0.63, p < 0.05). It was found that the digestion speed decreased nonlinearly with depth from 0.61 ± 0.16 μm/s (mean ± SD) in the superficial zone to 0.04 ± 0.02 μm/s in a region located at 70% of the cartilage thickness in depth. The relationship between the digestion depth and the exposure duration in trypsin could be described using a third order polynomial function. The full thickness of digested and undigested tissues was also measured using caliper, estimated from ultrasound data and histology sections, and compared. These findings indicate that ultrasound could provide useful information about the trypsin-induced progressive PG depletion in articular cartilage. Therefore, ultrasound represents a useful tool to evaluate the dynamics of models of OA in vitro in cartilage specimens in a research environment and this would ultimately help the in vitro examination of articular cartilage for research related to model of OA from the early stages of tissue degradation. |
| Title |
Recent advance of medical application of ultrasound developed by the ultrasonic research group in Juntendo University. |
| Author |
Wagai T, Tsuchidate M, Ito K, Ishii M, Katsumi S, Uematsu S, Ishikawa S, Takeuhi T, Ohashi H, Nonaka H, Takeuchi K, Abe Y, Arima M, Ouchi T, Kikuchi Y, Ide M, Uchida R |
| Journal |
Meet Diagn Use Ultrasound - Rotterdam |
| Volume |
|
| Year |
1963 |
| Abstract |
No abstract available. |
| Title |
Recent advances in sonodynamic approach to cancer therapy. |
| Author |
Umemura S, Kawabata K, Sasaki K, Yumita N, Umemura K, Nishigaki R. |
| Journal |
Ultrason Sonochem |
| Volume |
|
| Year |
1996 |
| Abstract |
Chemical agents such as porphyrins were found to be activated by ultrasound, producing significant antitumor effects. Hematoporphyrin (Hp) enhanced ultrasonically induced damage on sarcoma cells and shown a synergistic inhibitory effect on the tumor growth in combination with ultrasound at 2 MHz. Recently, other types of porphyrins such as protoporphyrin were also found to have such sonodynamic activities. Furthermore, it was found that sonochemical reactions can be greatly accelerated by superimposing the second harmonic onto the fundamental. The highest rate of iodine release from aqueous iodide was obtained at an acoustic intensity ratio between 1 MHz and 2 MHz of 1:1 while either one of the frequency components alone could not induce significant iodine release at the same total acoustic intensity. Second-harmonic superimposition in combination with sonodynamically active antitumor agents may have the potential for selective tumor treatment. |
| Title |
Recent advances in ultrasound assessment of occlusive arterial disease. |
| Author |
Fitzgerald DE, Gosling RG, Woodcock JP. |
| Journal |
N/A |
| Volume |
|
| Year |
1971 |
| Abstract |
No abstract available. |
| Title |
Recent developments in diagnostic ultrasound. |
| Author |
Shung KK. |
| Journal |
Crit Rev Biomed Eng |
| Volume |
|
| Year |
1987 |
| Abstract |
Ultrasound is being used increasingly in clinical diagnosis throughout the world in many medical specialties. Its major advantages over other imaging modalities are that it is minimally invasive, less expansive, and portable. Its resolution rivals that of X-ray computerized tomography and magnetic resonant imaging. Its limitations are that certain organs, such as lung and bone, are inaccessible by ultrasound, and that certain organs such as heart can only be accessed through limited acoustic windows. In recent years, great advances have been achieved in ultrasound imaging technology that make it even more versatile. Color Doppler flow imaging, parallel processing, Duplex scanning, and transesophageal imaging are just a few examples. In this paper, those developments, among others, are reviewed and their implications in clinical practice are discussed. |
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