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
 Friday, March 29th, 2024
BRL Home
About BRL
Publications
Projects
People
History
Facilities
Abstracts Database
Seminars
Downloads
Archives
Bioengineering Research Partnership
William D. O'Brien, Jr. publications:

Michael L. Oelze publications:

Aiguo Han publications:

BRL Abstracts Database

Search - a quick way to search the entire Abstracts Database.
 
Advanced Search - search specific fields within the Abstracts Database.
Title
Author
Journal
Volume
Year
Abstract Text
Sort by:     Title     Author     Journal     Year
Number of records to return:     10     20     30     50

Your search for ultrasound produced 3296 results.

Page 115 out of 330

Title Estimation of the acoustic impedance of lung versus level of inflation for different species and ages of animals.
Author Oelze ML, Miller RJ, Blue JP Jr, Zachary JF, O'Brien WD Jr.
Journal J Acoust Soc Am
Volume
Year 2008
Abstract In a previous study, it was hypothesized that ultrasound-induced lung damage was related to the transfer of ultrasonic energy into the lungs (W. D. O'Brien et al. 2002, “Ultrasound-induced lung hemorrhage: Role of acoustic boundary conditions at the pleural surface,” J. Acoust. Soc. Am. 111, 1102–1109). From this study a technique was developed to: 1) estimate the impedance (Mrayl) of fresh, excised, ex vivo rat lung versus its level of inflation (cm H2O) and 2) predict the fraction of ultrasonic energy transmitted into the lung (M. Oelze et al. 2003, “Impedance measurements of ex vivo rat lung at different volumes of inflation.” J. Acoust. Soc. Am. 114, 3384–3393). In the current study, the same technique was used to estimate the frequency-dependent impedance of lungs from rats, rabbits, and pigs of various ages. Impedance values were estimated from lungs under deflation (atmospheric pressure, 0 cm H2O) and three volumes of inflation pressure [7 cm H2O (5 cm H2O for pigs), 10 cm H2O, and 15 cm H2O]. Lungs were scanned in a tank of degassed 37 °C water. The frequency-dependent acoustic pressure reflection coefficient was determined over a frequency range of 3.5–10 MHz. From the reflection coefficient, the frequency-dependent lung impedance was calculated with values ranging from an average of 1.4 Mrayl in deflated lungs (atmospheric pressure) to 0.1 Mrayl for fully inflated lungs (15 cm H2O). Across all species, deflated lung (i.e., approximately 7% of the total lung capacity) had impedance values closer to tissue values, suggesting that more acoustic energy was transmitted into the lung under deflated conditions. Finally, the impedance values of deflated lungs from different species at different ages were compared with the thresholds for ultrasound-induced lung damage. The comparison revealed that increases in ultrasonic energy transmission corresponded to lower injury threshold values.


Title Estimation of the acoustic impedance of lung versus level of inflation for different species and ages of animals.
Author Oelze ML, Miller RJ, Blue JP Jr, Zachary JF, O'Brien WD Jr.
Journal J Acoust Soc Am
Volume
Year 2008
Abstract In a previous study, it was hypothesized that ultrasound-induced lung damage was related to the transfer of ultrasonic energy into the lungs (W. D. O'Brien et al. 2002, "Ultrasound-induced lung hemorrhage: Role of acoustic boundary conditions at the pleural surface," J. Acoust. Soc. Am. 111, 1102-1109). From this study a technique was developed to: 1) estimate the impedance (Mrayl) of fresh, excised, ex vivo rat lung versus its level of inflation (cm H(2)O) and 2) predict the fraction of ultrasonic energy transmitted into the lung (M. Oelze et al. 2003, "Impedance measurements of ex vivo rat lung at different volumes of inflation." J. Acoust. Soc. Am. 114, 3384-3393). In the current study, the same technique was used to estimate the frequency-dependent impedance of lungs from rats, rabbits, and pigs of various ages. Impedance values were estimated from lungs under deflation (atmospheric pressure, 0 cm H(2)O) and three volumes of inflation pressure [7 cm H(2)O (5 cm H(2)O for pigs), 10 cm H(2)O, and 15 cm H(2)O]. Lungs were scanned in a tank of degassed 37 degrees C water. The frequency-dependent acoustic pressure reflection coefficient was determined over a frequency range of 3.5-10 MHz. From the reflection coefficient, the frequency-dependent lung impedance was calculated with values ranging from an average of 1.4 Mrayl in deflated lungs (atmospheric pressure) to 0.1 Mrayl for fully inflated lungs (15 cm H(2)O). Across all species, deflated lung (i.e., approximately 7% of the total lung capacity) had impedance values closer to tissue values, suggesting that more acoustic energy was transmitted into the lung under deflated conditions. Finally, the impedance values of deflated lungs from different species at different ages were compared with the thresholds for ultrasound-induced lung damage. The comparison revealed that increases in ultrasonic energy transmission corresponded to lower injury threshold values.


Title Estimation of the scatterer distribution of the cirrhotic liver using ultrasound images.
Author Yamaguchi T, Hachiya H.
Journal Jpn J Appl Phys
Volume
Year 1998
Abstract In the B-mode image of the liver obtained by an ultrasonic imaging system, the speckled pattern changes with the progression of the disease such as liver cirrhosis. In this paper we present the statistical characteristics of the echo envelope of the liver, and the technique to extract information of the scatterer distribution from the normal and cirrhotic liver images using constant false alarm rate (CFAR) processing. We analyze the relationship between the extracted scatterer distribution and the stage of liver cirrhosis. The ratio of the area in which the amplitude of the processing signal is more than the threshold to the entire processed image area is related quantitatively to the stage of liver cirrhosis. It is found that the proposed technique is valid for the quantitative diagnosis of liver cirrhosis.


Title Estimation of the speed of ultrasound propagation in biological tissues: a beam-tracking method.
Author Ophir J.
Journal IEEE Trans UFFC
Volume
Year 1986
Abstract A pulse-echo beam-tracking method for the estimation of the speed of sound in tissue is described. We have shown that precision on the order of +/- 0.5 percent and accuracy on the order of 1 percent are obtainable in uniformly scattering foam phantoms using several echo-waveforms which are several centimeters long. The precision could be improved if 1) more uniform tissues or phantoms are used, 2) more uncorrelated echo-waveforms are examined, and 3) the length of each echo-waveform is extended. The potential effects due to refractive layers on the estimation are discussed.


Title Estimation of total attenuation and scatterer size from backscattered ultrasound waveforms.
Author Bigelow TA, Oelze ML, O'Brien WD Jr.
Journal J Acoust Soc Am
Volume
Year 2005
Abstract Quantitative ultrasound techniques using backscattered echoes have had limited success in vivo due to the frequency-dependent attenuation along the entire propagation path masking the frequency dependence of the backscatter. Herein, total attenuation and scatterer size are estimated simultaneously by an analysis of the in vivo backscattered power spectrum using two approaches. The simulations used to evaluate the two approaches used frequencies between 4 and 11 MHz with an effective scatterer radius of 25 ?m. The first approach was based on approximations of the in vivo backscattered power spectrum (i.e., assumed Gaussian function), wherein attenuation and size were estimated by assuming each was a Gaussian transformation performed on Gaussian power spectra. The approach had poor accuracy due to the backscattered power spectra not being sufficiently modeled by a Gaussian function. The second approach estimated attenuation and size by fitting a modified reference spectrum to the in vivo backscattered power spectrum without any assumptions about the shape of the spectrum. The accuracy of the size estimate was better than 20% for signal-to-noise ratio >6 dB, window lengths greater than 4 mm, and attenuation between 0 and 1 dB/cm-MHz. However, the precision quickly degraded with increasing noise, increasing attenuation, and decreasing window length.


Title Ethylene glycol-water mixture for use in ultrasound test objects.
Author Goldstein A, Langrill LN.
Journal J Clin Ultrasound
Volume
Year 1979
Abstract Ethylene glycol-water mixtures have been found suitable for use in ultrasound test objects. A plot of the required percentage of ethylene glycol with room temperature for an acoustic velocity of 1540 m/sec is presented to aid the clinical user. The.velocity measurements performed are shown to be dominated by near-field transient diffraction effects. A 30 percent ethylene glycol-water mixture has been found to have a constant acoustic velocity of 1638 +/- 3.5 m/sec over a wide temperature range (15.6 degrees C-38.4 degrees C). This mixture is suitable for a test object velocity standard. Proper use of the A.I.U.M. 100-mm test object is discussed.


Title Evaluating bone by ultrasound.
Author Liu P.
Journal Thesis(PhD): The University of Texas Southwestern Medical Center at Dallas
Volume
Year 2008
Abstract Bone fractures associated with osteoporosis, a major bone disease characterized by low density and high fracture risk, are common causes of disability and large medical care expenses around the world. Considering its low cost, high portability, and non-ionizing nature, non-invasive ultrasound techniques have been investigated as tools for evaluating bone quality and biomechanical competence. Quantitative ultrasound has been used clinically as a surrogate for the current gold standard measure in osteoporosis diagnosis - Bone Mineral Densitometry (BMD), which unfortunately utilizes ionizing radiation. This study proposes the application of a reflection ultrasound method to evaluate non-BMD properties of cancellous bone, including porosity and the microstructure of the trabecular network, all of which are directly related to bone morphological changes caused by osteoporosis and could result in better predictions of fracture risk. Computer simulations and phantom studies were adopted to guide the measurement of bone properties. In the computer simulations, the cellular model and the wire model of cancellous bone predict the backscattering dependence on porosity from two different perspectives, but reach the same result. This leads to the first conclusion that reflection ultrasound is not sensitive to the shape of a scatter of wavelength size but to the spacing between scatters. The in vitro cancellous bone study demonstrated that the average porosity is correlated with the density, while the local porosity depends upon the heterogenity of the cancellous bone. The average porosity of cancellous bone can be directly determined from ultrasound signals reflected from the bone. Results of the ex vivo and in vivo short bone studies in patella are in agreement with that of Ultrasound Critical-angle Reflectometry (UCR). Thus, the second conclusion of this dissertion is that reflection ultrasound can be an effective tool for assessing bone properties in vivo. During the short bone-mimicking phantom study, the first critical angle detected by UCR was shown to correspond to the solid ultrasound velocity and is independent of porosity, but its amplitude is strongly related to porosity; the second critical angle, corresponding to bulk ultrasound velocity, is stronger related to porosity, but the correlation between its amplitude and the porosity is weak.


Title Evaluating ultrasound propagation through tissue layers mapped from medical images.
Author Sun J, hynynen K.
Journal J Acoust Soc Am
Volume
Year 1998
Abstract No abstract available.


Title Evaluation of accuracy of a theoretical model for predicting the necrosed tissue volume during focused ultrasound surgery.
Author Damianou CA, Hynynen K, Fan X.
Journal IEEE Trans UFFC
Volume
Year 1995
Abstract The concept of thermal dose as a predictor for the size of the necrosed tissue volume during high-intensity focussed ultrasound surgery was tested. The sensitivity of the predicted lesion size to the uncertainties in the iso-dose constant, attenuation coefficient, and thermal dose threshold of necrosis was studied. The predicted lesion size appears to be independent of attenuation at some high attenuation values and certain depth in tissue. Thus, for a given target depth, a proper selection of frequency could minimize the lesion size variability due to uncertainty in the tissue attenuation. The predicted lesion size was less dependent on the uncertainties in the iso-dose constant and thermal dose of necrosis. The predictions of the model were compared with experimental data in rabbit muscle, and experimental data in cat and rat brain measured by others. The agreement was found to be good in most of the experiments. Similarly, the model was found to predict well the trends of increasing power and pulse duration.


Title Evaluation of an aperiodic phased array for prostate thermal therapies.
Author Hutchinson EB, Buchanan MT, Hynynen K.
Journal Proc IEEE Ultrason Symp
Volume
Year 1995
Abstract A 57 element aperiodic linear phased array was designed and constructed to investigate the feasibility of using transrectal ultrasound for thermal therapeutic treatment of diseases of the prostate. A method of reducing grating lobe levels by using optimized random distributions of unequally sized elements was used, which made it feasible to use larger elements and hence fewer elements and amplifier channels, while still achieving acceptable power field patterns. The heating capabilities of this array were investigated using an ex vivo perfused kidney for hyperthermia and fresh bovine liver for thermal surgery. The experiments demonstrated that the aperiodic array was capable of generating and controlling adequate power for the purposes of hyperthermia and thermal surgery.


Page 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85 | 86 | 87 | 88 | 89 | 90 | 91 | 92 | 93 | 94 | 95 | 96 | 97 | 98 | 99 | 100 | 101 | 102 | 103 | 104 | 105 | 106 | 107 | 108 | 109 | 110 | 111 | 112 | 113 | 114 | 115 | 116 | 117 | 118 | 119 | 120 | 121 | 122 | 123 | 124 | 125 | 126 | 127 | 128 | 129 | 130 | 131 | 132 | 133 | 134 | 135 | 136 | 137 | 138 | 139 | 140 | 141 | 142 | 143 | 144 | 145 | 146 | 147 | 148 | 149 | 150 | 151 | 152 | 153 | 154 | 155 | 156 | 157 | 158 | 159 | 160 | 161 | 162 | 163 | 164 | 165 | 166 | 167 | 168 | 169 | 170 | 171 | 172 | 173 | 174 | 175 | 176 | 177 | 178 | 179 | 180 | 181 | 182 | 183 | 184 | 185 | 186 | 187 | 188 | 189 | 190 | 191 | 192 | 193 | 194 | 195 | 196 | 197 | 198 | 199 | 200 | 201 | 202 | 203 | 204 | 205 | 206 | 207 | 208 | 209 | 210 | 211 | 212 | 213 | 214 | 215 | 216 | 217 | 218 | 219 | 220 | 221 | 222 | 223 | 224 | 225 | 226 | 227 | 228 | 229 | 230 | 231 | 232 | 233 | 234 | 235 | 236 | 237 | 238 | 239 | 240 | 241 | 242 | 243 | 244 | 245 | 246 | 247 | 248 | 249 | 250 | 251 | 252 | 253 | 254 | 255 | 256 | 257 | 258 | 259 | 260 | 261 | 262 | 263 | 264 | 265 | 266 | 267 | 268 | 269 | 270 | 271 | 272 | 273 | 274 | 275 | 276 | 277 | 278 | 279 | 280 | 281 | 282 | 283 | 284 | 285 | 286 | 287 | 288 | 289 | 290 | 291 | 292 | 293 | 294 | 295 | 296 | 297 | 298 | 299 | 300 | 301 | 302 | 303 | 304 | 305 | 306 | 307 | 308 | 309 | 310 | 311 | 312 | 313 | 314 | 315 | 316 | 317 | 318 | 319 | 320 | 321 | 322 | 323 | 324 | 325 | 326 | 327 | 328 | 329 | 330