Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
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William D. O'Brien, Jr. publications:

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Title Ultrasound enhances gene expression of liposomal transfection.
Author Unger EC, McCreery TP, Sweitzer RH.
Journal Invest Radiol
Volume
Year 1997
Abstract RATIONALE AND OBJECTIVES: Cationic liposomes are under development as delivery agents for gene therapy. The authors studied the effect of ultrasound on gene expression in cell cultures during liposomal transfection experiments. METHODS: Cationic liposomes of dipalmitoylethylphosphocholine and dioleoylphosphatidylethanolamine were used to transfect cultured HeLa, NIH/3T3, and C127I cells with the chloramphenicol acetyl transferase (CAT) gene. A cell viability assay was performed on cultured HeLa cells that were exposed to varying durations (5 seconds or 30 seconds) and intensities of 1 MHz continuous-wave therapeutic ultrasound after transfection, and gene expression was measured 48 hours later. RESULTS: Cells survived 30 seconds or less at a power level of 0.5 watts/cm2 but died when exposed for 60 seconds or longer. Exposures of 5 seconds and 30 seconds of ultrasound resulted in significant increases in gene expression in all three cell types tested in this experiment. CONCLUSIONS: Relatively low levels of ultrasound energy can be used to enhance gene expression from liposomal transfection. Additional experiments are needed to optimize this process and clarify the mechanisms involved.


Title Ultrasound enhances treatment.
Author Unknown.
Journal medical Alumni News
Volume
Year 1974
Abstract No abstract available.


Title Ultrasound examination frequencies appropriate for breast tissue: effects of frequency change on scattering and contrast resolution.
Author Kelly-Fry E, Holden RW, Jackson VP, Morris ST, Sanghvi NT.
Journal J Ultrasound Med
Volume
Year 1986
Abstract In a current research study, patients previously identified as having solid breast masses are examined by an automatic ultrasound instrument that incorporates a transducer pulsed under conditions which allow the operator to vary, without transducer replacement, frequency of the examining beam. Frequencies of 3.5, 4.5, 6.5 and 8 MHz are currently available. Frequencies above 8 MHz are scheduled for this investigation. An automatic, bi-plane scanning technique allows multiple frequency examinations at scanning planes of the mass that are mutually perpendicular. The primary purposes of these approaches are to: collect image data on the variation in the scattering characteristics of benign and malignant masses in order to further improve the diagnostic accuracy of ultrasound imaging; to evaluate the diagnostic importance of the increased backscatter from breastfat at higher frequencies. Our preliminary clinical studies, using separate 4 and 7.5 MHz transducers, indicated that as the frequency increases, the backscatter from breast fat is signifcantly greater than that from malignant and benign breast masses. Differences between the frequency dependent, backscatter value of fat and that of non-fatty breast masses allows, by means of frequency manipulation, dynamic control over some aspects of contrast resolution.


Title Ultrasound examination of symptomatic patients and its relation to ultrasound breast screning.
Author Kelly-Fry E, Harper AP.
Journal Proc 25th Annual meeting Am Inst Ultrasound Med
Volume
Year 1980
Abstract No abstract available.


Title Ultrasound examination of the breast.
Author Griffiths K.
Journal Med Ultrasound
Volume
Year 1978
Abstract Ultrasound examination of the breast provides considerable information about the tissue composition of the breast. The technique is useful for the detection and diagnosis of a variety of benign conditions such as fibroadenomas, fibroadenosis, duct ectasia, mammary dysplasia, and fatty infiltration and is particularly reliable in the detection of cysts and of liquid-filled ducts greater than 2 mm where its accuracy is greater than 98 percent. In combination with physical examination ultrasound allows the identification of 90 percent of malignant lesions over 1 cm in diameter. Because no ionizing radiation is employed, it is a safe examination and may be performed and repeated frequently in women of all ages. For these reasons in our clinic this technique is used as the first imaging procedure in breast examination. The results obtained in the ultrasonic examination of the breast will be described.


Title Ultrasound exposure decreases sperm production in men, animals.
Author Unknown.
Journal JAMA
Volume
Year 1976
Abstract No abstract available.


Title Ultrasound fields in an attenuating medium.
Author Jensen JA, Gandhi DR, O'Brien WD Jr.
Journal Proc Ultrason Symp IEEE
Volume
Year 1993
Abstract Ultrasound fields propagating in tissue will undergo changes in shape not only due to diffraction, but also due to the frequency dependent attenuation. Linear fields can be fairly well predicted for a non-attenuating medium like water by using the Tupholme-Stepanishen method for calculating the spatial impulse response, whereas the field cannot readily be found for an attenuating medium. In this paper we present a simulation program capable of calculating the field in a homogeneous attenuating medium. The program splits the aperture into rectangles and uses a far-field approximation for each of the rectangles and sums all contributions to arrive at the spatial impulse response for the aperture and field point. This approach makes it possible to model all transducer apertures, and the program can readily calculate the emitted, pulse-echo and continuous wave field. Attenuation is included by splitting it into a frequency dependent part and frequency independent part. The latter results in an attenuation factor that is multiplied onto the responses from the individual elements, and the frequency dependent part is handled by attenuating the basic one-dimensional pulse. The influence on ultrasound fields from attenuation is demonstrated.


Title Ultrasound fields in attenuating media.
Author Lerch R, Friedrich W.
Journal J Acoust Soc Am
Volume
Year 1986
Abstract For medical ultrasonic imaging and for nondestructive testing, the attenuation of pressure waves and the resulting shift in wave velocity are important features in commonly used transmission media such as biological tissue. An algorithm for the numerical evaluation of pressure field distributions generated by ultrasonic transducers is presented. The attenuation and dispersion of the sound transmission medium are taken into consideration. The sound fields are computed numerically for continuous wave as well as pulse excitation. The transducer has plane or gently curved geometry and is embedded in a plane rigid baffle. The numerically determined pressure fields are presented as 3D plots, as gray-scale images for a fixed time stamp (like a snapshot), or as isobars regarding the maximum values over time for each local point in the area under investigation. The algorithm described here can be utilized as a tool for design of ultrasound transducers, especially array antennas.


Title Ultrasound fiffraction and Fourier optical determination of average scatterer spacing in a random medium.
Author Lerner RM, Lee PPK, Waag RC.
Journal Rep Univ Rochester Dept Elect Eng
Volume
Year 1976
Abstract No abstract available.


Title Ultrasound findings in hepatitis.
Author Kurtz AB, Rubin CS, Cooper HS, Nisenbaum HL, Cole-Beuglet C, Medoff J, Goldberg BB.
Journal Radiology
Volume
Year 1980
Abstract A retrospective study of ultrasound images of the liver in patients with hepatitis was undertaken. Two distinct ultrasound patterns were detected. In acute hepatitis, the predominant findings were accentuated brightness and more extensive demonstration of the portal vein radicle walls and overall decreased echogenicity of the liver. Chronic hepatitis primarily revealed decreased brightness and number of portal vein radicle walls and verall increased liver echogenicity. In addition, the pathological severity closely paralleled these ultrasound patterns. A prospective study confirmed the same acute hepatitis ultrasound findings with close correlation to the clinical severity. These distinct ultrasound patterns will help to evaluate patients with suspected acute and chronic hepatitis and more accurately define intrahepatic causes of jaundice.


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