AND FREQUENCY CONTROL
| A PUBLICATION OF THE IEEE ULTRASONICS, FERROELECTRICS AND FREQUENCY CONTROL SOCIETY |  |
(ISSN 0885-3010)
| IEEE TRANSACTIONS ON | ||||||
| ULTRASONICS,
FERROELECTRICS,
AND FREQUENCY CONTROL |
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| 2001 | VOLUME 48 | ITUCER |
(ISSN 0885-3010)
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January 2001 - Image courtesy of W. F. Walker, T. J. Mondzelewski, F. J. Fernandez, M. J. McAllister of the University of Virginia, R. E. Davidsen of ATL Ultrasound, and C. A. Toth of Duke University Radiation Force Images of Tissue Mimicking Phantoms The cover depicts B-Mode and radiation force images obtained from tissue mimicking phantoms. The color bar indicates maximum radiation force induced displacement on a scale of microns. Phantoms were formed of acrylamide gel with graphite added as a scattering agent. Phantoms were extremely soft with elastic moduli of roughly 1 Pa. |
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March 2001 - Image courtesy of E. D. Light and S. W. Smith (Department of Biomedical Engineering, Duke University, Durham, NC 27708) and J. O. Fiering (Department of Electrical and Computer Engineering, Duke University). The cover shows our work with two dimensional array transducers for real time volumetric imaging. Fig. 1(a) is a 2-D array transducer built on a multi-layer flex (MLF) interconnect. Fig. 1(b and c) shows real time orthogonal B-scans from a 5-MHz 2-D array transducer built on this flex. The images show the right ventricle, left ventricle, mitral valve, aortic valve, and the intra-ventricular septum from an open-chested sheep. Fig. 2(a) is a 5.0-MHz 2-D array transducer built on an MLF designed to fit into a 12 French catheter for intracardiac scanning. Fig. 2(b) shows a B-scan of an excised sheep left atrium showing the pulmonary veins. Fig. 2(c) is the corresponding real time C-scan showing the os of the two veins. UFFC article detailing this work: J. O. Fiering, P. Hultman, W. Lee, E. D. Light, and S. W. Smith. "High-density flexible interconnect for two-dimensional ultrasound arrays," IEEE Trans. Ultrason., Ferroelect., Freq. Contr., vol. 47, no. 3, pp. 764-770, 2000. |
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May 2001 - Images courtesy of Elisa Konofagou, Brian Garra, and Jonathan Ophir, University of Texas Medical School, Houston and University of Vermont Medical Center Sonograms and corresponding elastograms of benign and malignant breast tumors in vivo. The elastograms were generated unsing a compression of approximately 1% (i.e., 0.01 strain). Black and white denote stiffer (lower strain) and softer (higher strain) tissue areas, respectively. In the benign case, the patient was in the sitting position (i.e., the direction of compression was along the body), and in the malignant case, the patient was supine (i.e., the direction of compression was perpendicular to the body). The elastograms can play a complimentary role to sonography, not only for tumor detection but also tumor characterization. The measured transverse diameter of benign tumors on elastograms is almost always the same or smaller than their diameter on sonography (upper panel); that of cancers is generally larger on elastograms than on sonograms (lower panel). This could be explained by the fact that benign breast tumors generally have smooth regular borders and are loosely bound to the surrounding tissues. Cancers are usually characterized by their firm desmoplastic reactions within the surrounding tissue. Therefore, in the latter case, some of the surrounding tissue could be included as part of the tumor measurement in elastography by being forced to follow the tumor motion during compression. Using the combination of tumor measured strain and the difference between the sonographic and elastographic tumor measured diameter, the differentiation between benign and malignant tumors has been previously shown to be feasible. This work was supported in part by a Program Project Grant P01-CA64597 from the National Cancer Institute to the University of Texas. |
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July 2001 - These images were taken from a paper published in this issue of the Transactions. Top: The sound field produced by an array transducer is a superposition of wavelets of different amplitude, frequency, and phase. This interference is very subtle, and computer simulations showed that the highest peak negative pressures can occur lateral in a sector image. Bottom: Bubble destruction (color) was measured in a gelatin contrast phantom and plotted on top of a B-mode gray-scale image of the phantom together with the simulated pressure field (blue, solid lines). The results support the hypothesis that the occurence of peak negative pressures and bubble destruction are correlated. |
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September 2001 - Graphics preparation by T. Stengelin Scanning Acoustic Force Microscopy (SAFM) is a simple and powerful technique for the investigation of ultrasonic surface waves. It combines the detection of sub-Å amplitudes with nanometer lateral resolution. The cover image shows the SAFM amplitude of a circular SAW transducer (inner diameter, 4 µm) on (100) GaAs. Waves are launched in preferred directions with high electromechanical coupling for SAWs and PSAWs. Thanks to J.S. Harris, the DFG, the DAAS, and the NSF for supporting this work. |
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November 2001 Comparison of histology (top) and elasticity micrograph (bottom) of an engineered smooth muscle tissue construct. The histology sections clearly delineate a smooth muscle cell layer near the top of a construct consisting of a polyglycolic acid fiber (PGA) scafolding seeded with smooth muscle cells and implanted in a rat model. Note that the smooth muscle cell layer is missing from an unseeded control construct on the right. Strain images of the same samples obtained with an elasticity microscope are presented in the lower row. The noninvasive elasticity microscope clearly identifies the smooth muscle cell layer in the seeded construct. |