Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

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Your search for ultrasound produced 3296 results.

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Title Evaluation of backscattering coefficients for excised human tissues: results, interpretation and associated measurements.
Author Nicholas D.
Journal Ultrasound Med Biol
Volume
Year 1982
Abstract Measurements are reported on the ultrasonic attenuation coefficient, the velocity of sound propagation and the differential scattering coefficient (for 180° scattering) for 3 types of freshly excised normal human tissues: liver, spleen and brain (white matter). The measurements are made as a continuous function of frequency in the range 0.7–7 MHz. The data for attenuation and scattering are consistent with a power law dependence on frequency though the latter are best described by a two-term fit. Comparison of the scattering data with theory suggests that two forms of tissue structure, with characteristic dimensions of approx. 1 and 0.02 mm, are predominantly responsible for scattering in the frequency range 0.5–5 MHz. The absolute value of backscattering for freshly excised human liver tissue at 1 MHz is 3.5 × 10−4cm−1Sr−1 rising to 9.0 × 10−4cm−1Sr−1 at 3 MHz. Extrapolation to total scattering suggests that the contribution of scattering to attenuation varies from approx. 2% at 1 MHz to 5.4% at 3 MHz.


Title Evaluation of calcification detectability in female breasts by ultrasound.
Author Filipczynski L, Kujawska T, Lypacewicz G.
Journal Arch Acoust
Volume
Year 1990
Abstract The authors investigated detectability of calcifications by means of shadow and echo methods for 5 MHz frequency. Computing the ultrasonic field distribution around a rigid sphere they determined the shadow range and hence the detectability condition for calcification diameter ? * 3 mm. For the echo method former investigations were continued improving the measurement technique and expanding the analysis. To determine the tissue signal background level measurements were performed on 82 breasts of healthy premenopause women. The boundaries of various tissues and inhomogeneities within cause interfering background and its level limits the detectability. The measurement results, confirmed statistically, were used for detectability determination in normal breast tissues [attenuation 1.1 dB/(cm x MHz)]. The calculations show that the minimum diameter of a detectable calcification ? = 0.4 mm for a normal breast. Jackson et al [18] and Kasumi [19,20] have demonstrated calcifications 0.1-0.5 mm in dia with frequencies of 4 and 7.5 MHz. These results are in general agreement with our theory if one takes into account the high (SD = 8 dB) scattering of the signal background measurement results. When detecting calcifications in the tumor anechoic area one obtains stressing of fine calcification echoes, thus increasing the detectability when comparing with the case of healthy breast tissues.


Title Evaluation of ciliary body detachment in hypotony.
Author Coleman DJ.
Journal Retina
Volume
Year 1995
Abstract PURPOSE: This article describes an anatomic classification for the hypotonous eye and links this classification with approaches to the surgical treatment of this condition. The classification is based on very-high-resolution ultrasound scans and three-dimensional reconstruction of planar ultrasound scans. METHODS: Standard 10-MHz B-scans and very-high-resolution (40-60 MHz) scans were performed with a planar motor system using the immersion method. The anatomic changes in the hypotonous eye were classified and correlated with clinical and ultrasonographic findings at the time of therapeutic intervention and after resolution of the hypotonous condition. RESULTS: Hypotony is defined as low intraocular pressure most commonly due to ciliary body detachment or ciliary body dysfunction. With ciliary body detachment, three anatomically related causative types were identified: tractional hypotony, which has ultrasonographically demonstrable proliferative vitreociliopathy with membrane attachments between the ciliary body, iris, and formed vitreous; dehiscence hypotony, which has a modification in the scleral acoustic architecture consistent with a scleral break or wound dehiscence; and primary type hypotony, which has ciliary body detachment but no ultrasonographically demonstrable tractional component or scleral anatomic modification, but may have an iris scleral separation. CONCLUSIONS: Each type of ciliary body detachment hypotony may have a different management approach, so high-resolution ultrasound, particularly when shown with sequencing or three-dimensional displays to demonstrate the extent of detachment, can aid in the selection and implementation of appropriate therapy.


Title Evaluation of classification strategies using quantitative ultrasound markers and a thyroid cancer rodent model
Author Montero ML, Zenteno O, Castaneda B, Oelze M, Lavarello R
Journal IEEE Int Ultrasonics Symp Proc
Volume
Year 2014
Abstract The incidence rate of diagnosed thyroid cancer has increased over the last decades. Although ultrasonic imaging has increased the malignancy detection rate, current ultrasonography markers do not provide a sufficient level of diagnostic accuracy to replace the fine needle aspiration biopsy. Recently, studies have reported that significant differences were observed in the values of quantitative ultrasound (QUS) parameters derived from a thyroid cancer rodent model between normal/benign and malignant tissues. In the present study, the performance of a multi-parametric classification for the differentiation of thyroid cancer in this rodent model has been evaluated. The experimental database consisted of 32 mice having different predispositions to developing thyroid abnormalities; 6 of them developed thyroid cancer papillary carcinoma (PTC), 5 follicular variant papillary thyroid carcinoma (FV-PTC), 6 developed benign tumors (c-cell adenoma) and 15 did not develop any thyroid abnormalities. Backscattered data was obtained from excised thyroid tissues using a 40 MHz, f/3 single element transducer. A total of five QUS parameters were derived from the ultrasound data: two from backscatter coefficients (i.e., the effective scatterer diameter (ESD) and effective acoustic concentration (EAC)), two from envelope statistics (i.e., the μ and k parameters), and one from ultrasound attenuation (i.e., attenuation coefficient slope). A twoclass classification between normal/benign and malignant cases was performed using linear discriminant analysis with both one and two-dimensional feature spaces. When using a two dimensional feature space, it was found that the combination of EAC and 10/μ resulted in both a sensitivity and specificity of 100%.


Title Evaluation of ohmic instrument company model UPM-30 ultrasound power meter.
Author Abzug JL.
Journal Rep U S Dept HEW
Volume
Year 1978
Abstract The Bureau of Radiological Health and the National Bureau of Standards have evaluated a comercially available ultrasound power meter designed to measure the outputs from ultrasonic physical therapy units. The parameters investigated include accuracy, repeatability, temperature and position dependence, and ultrasound transmission medium dependence.


Title Evaluation of quantitative ultrasound tissue characterization of the cervix and cervical length in the prediction of premature delivery for patients with spontaneous preterm labor.
Author Tekesin I, Hellmeyer L, Heller G, Romer A, Kuhnert M, Schmidt S.
Journal Am J Obstet Gynecol
Volume
Year 2003
Abstract Objective: This study was to evaluate the predictive value of the uterine cervix tissue with the use of quantitative ultrasound gray level analysis for preterm delivery. Study design: Sixty-eight patients with preterm labor between 20 and 35 week s of gestation were included. When two-dimensional transvaginal ultrasound measurement of cervical length was completed, a region of interest of constant size was defined in the midsection of the posterior wall, and the tissue-specific gray scale was determined. Preterm delivery of <37 weeks of gestation was sought. Results: Twenty-eight patients (41.2%) were delivered preterm. The risk for preterm delivery was increased significantly in patients with cervical length of <2.5 cm (odds ratio, 7.67; 95% CI, 2.4-24.45), with Bishop score of >4 (odds ratio, 3.44;95%CI, 1.21-9.75), and with decreased mean gray scale value (odds ratio, 12.13; 95% CI, 3.69 ? 39.88). Parity and uterine contractions were not significant as predictors for preterm delivery, although preterm delivery remained nearly the same by uterine contractions (odds ratio, 0.92; 95% CI, 0.28-3.01). A mean scale value of <6.54 had the best cutoff value for the prediction of preterm delivery. For preterm deliver, a mean gray value <6.54 had a sensitivity of 82.1%, a specificity of 72.5%, a positive predictive value of 67.6%, and a negative predictive value 85.3%. Multiple logistic regression analysis indicated that, even when other variables are considered simultaneously, the mean gray scale value is the single best predictor of preterm delivery. Conclusion: Quantitative ultrasound tissue characterization of the uterine cervix predicts premature delivery and provides additional information in the prediction of potential premature delivery.


Title Evaluation of reactive hyperemia in the human limb by doppler ultrasound & nuclear magnetic resonance.
Author Strosin RG, Battocletti JH, Sances A Jr, Knox TA.
Journal J Clin Eng
Volume
Year 1988
Abstract The phenomenon of reactive hyperemia is used to demonstrate the potential clinical application of the continuous-wave NMR flowmeter in the measurement of the steady component of arterial blood flow. An ultrasound study of 15 normal volunteers showed steady flor to be small or nonexistent, particularly in the leg. Therefore, reactive hyperemia was used to induce a steady component in arterial blood flow. But since reactive hyperemia can be used to evaluate peripheral circulation in the human limb, the characteristics of reactive hyperemia are presented and studied for their own worth. A bi-directional Doppler ultrasound velocimeter was used to verify a normal steady component existing in limb blood flow as well as the nature of the change in blood flow caused by reactive hyperemia.


Title Evaluation of research reports: Bioeffects literature review.
Author Bioeffects Committee.
Journal Am Inst Ultrasound Med
Volume
Year 1984
Abstract No abstract available, report evaluations.


Title Evaluation of research reports: Bioeffects literature reviews.
Author Bioeffects committee of the American Institute of Ultrasound in Medicine; chaired by Frizzell LA.
Journal Rep AIUM
Volume
Year 1984
Abstract No abstract available.


Title Evaluation of the attenuation coefficients in normal and pathological breast.tissue.
Author Landini L, Sarnelli R.
Journal Med Biol Eng Comput
Volume
Year 1986
Abstract The authors report on measurements of frequency-dependent attenuation in normal and pathological breast tissue. Measurements were performed by using pulsed transmitted ultrasound. Five groups of breast specimens including fatty tissue, fibrofatty parenchyma and fibrosis, malignant tumours with and without productive fibrosis have been studied. The results of the attenuation measurements indicate that the attenuation coefficient is lower for tissues with large predominance of cells (fatty tissue, medullary carcinoma) and increases with collagen fibre content (infiltrating ductal carcinoma scirrhous type, fibrosis, fibrofatty). A comparative nonlinear (best fitting) and linear analysis of the attenuation curves shows that it does not matter whether one uses a linear or nonlinear equation to describe the attenuation curves.


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