|
|
|
BRL Abstracts Database |
Your search for ultrasound produced 3296 results. Page 225 out of 330
Title |
Seizing the science of ultrasound-beyond imaging and into physiology and therapeutics. |
Author |
McPherson DD,Holland CK. |
Journal |
J Am Coll Cardiol |
Volume |
|
Year |
2003 |
Abstract |
No abstract available. |
Title |
Selected biological effects of ultrasound. |
Author |
Dunn F. |
Journal |
Book Chapter |
Volume |
|
Year |
1982 |
Abstract |
No abstract available. |
Title |
Selective action of ultrasound on nerve tissue. |
Author |
Fry WJ, Barnard JW. |
Journal |
Conv Rec IRE |
Volume |
|
Year |
1954 |
Abstract |
A description of the ultrasonic method of producing selective accurately localized lesions in central nervous systems is presented. The apparatus and technique are briefly described. Results of a study of ultrasonically produced lesions of the internal capsule of cats are discussed. The present state of our knowledge of the physical factors involved in the fundamental mechanism is outlined. |
Title |
Selective clinical ultrasound signals mediate differential gene transfer and expression in two human prostate cancer cell lines: LnCap and PC-3. |
Author |
Tata DB, Dunn F, Tindall DJ. |
Journal |
Biochem Biophys Res Commun |
Volume |
|
Year |
1997 |
Abstract |
Low intensity ultrasound signals, similar to that employed in clinical.therapy, are found to mediate differential gene transfer and expression of the Green Fluorescence Protein (GFP) reporter in two human prostate cancer cell lines, LnCap and PC-3. Cell suspensions in the presence or in the absence of GFP (44.5nM) were treated at 37 degrees C under a standing wave condition. Cells were exposed to either continuous wave, 932.7kHz ultrasound, or to several independent bursts, each burst comprising a 20% duty cycle.(932.7kHz) sine wave. The burst "repetition" frequency was varied from 10Hz to 10kHz in several different experiments and each treatment received a net identical ultrasound energy exposure. Transient GFP expression levels in viable cells were monitored by flow cytometry. The findings revealed a strong ultrasound tone-burst frequency dependence on the transfection efficiencies. Interestingly, the ultrasound signal parameters which are routinely employed in clinical therapy did not yield any statistically significant enhancement in transfection efficiency relative to their sham counterparts. |
Title |
Self-guided ultrasound phased arrays for noninvasive surgery. |
Author |
Ebbini ES. |
Journal |
Proc SPIE |
Volume |
|
Year |
2001 |
Abstract |
A dual-mode high-power ultrasound phased array with imaging capability to allow for self-guidance in noninvasive thermal surgery is described. Criteria governing the design of such dual-mode arrays to allofor high therapeutic efficiency and adequate image contrast in the target volume are given. Experimental results for characterization of the array in both the imaging and therapy modes are given. Having established the dual-mode capabilities of this array, we have recently conducted a series of experiments in forming discrete and volumetric lesions in freshly excised tissue samples. Experimental results demonstrating the feasibility of visualizing the lesion formation process are presented. Images formed before and after discrete lesion formation have consistently shown increased level of echogenicity at the lesion location. Similar results were obtained for volumetric lesions. These results show that the spatial mapping of the lesion size and shape based ultrasound images obtained using the therapeutic array is feasible. |
Title |
Semi-automatic determiantion of ultrasonic velocity and absorption in liquids. |
Author |
Kessler LW, Hawley SA, Dunn F. |
Journal |
Acustica |
Volume |
|
Year |
1971 |
Abstract |
A reliable semi-automatic pulse technique for rapidly determining the velocity and absorption of ultrasound in liquids over the frequency range from 1MHz to 200 MHz is described. The acoustic path length is changed at a known constant rate and the velocity of sound is determined from the length of time for the path length to change by an integral number of wavelengths. The absorption is determined from the slope of the line which results from recording logarithmically the received pulse amplitude as a function of the instantaneous path length. |
Title |
Semiautomatic detection of microbubble ultrasound contrast agent destruction applied to definity® using support vector machines. |
Author |
hakk A, Lavarello R, O'Brien WD, Jr. |
Journal |
Proc IEEE Ultrasonic Symposium |
Volume |
|
Year |
2007 |
Abstract |
For different applications such as imaging, drug delivery, and tissue perfusion measurement, it is necessary to know the inertial cavitation (IC) threshold of ultrasonic contrast agent (UCA) microbubbles. Even though the influence of the
incident acoustical pressure, frequency and pulse duration (PD)in the regime of the microbubble’s response is well established,the investigation of the IC threshold is essential for the accuracy of some measurement techniques and for ultrasound safety. The goal of our work was to find the IC threshold for the FDAapproved UCA Definity®. The dependency of the threshold on the peak rarefactional pressure and PD of an incident toneburst was investigated. The experiments performed to estimate IC thresholds yield a large amount of data to be classified in the five following classes: Noise, Oscillation, Collapse, Multiple Bubbles and Unknown. A reduction of the manually to classified
data was reduced by using a semiautomatic algorithm in order to achieve a low variance in the IC estimates. Further more significant features to distinguish between classes were found and tested. The development of a heuristic algorithm to detect events of thee class Collapse was not successful due to the fact
that the classes were overlapping and some signals could not be classified to a single class. Therefore, a semiautomatic algorithm using support vector machines was developed. |
Title |
Semiautomatic three-dimensional segmentation of the prostate using two-dimensional ultrasound images. |
Author |
Wang Y, Cardinal HN, Downey DB, Fenster A. |
Journal |
Med Phys |
Volume |
|
Year |
2003 |
Abstract |
In this paper, we report on two methods for semiautomatic three-dimensional (3-D) prostate boundary segmentation using 2-D ultrasound images. For each method, a 3-D ultrasound prostate image was sliced into the series of contiguous 2-D images, either in a parallel manner, with a uniform slice spacing of 1 mm, or in a rotational manner, about an axis approximately through the center of the prostate, with a uniform angular spacing of 5 degrees. The segmentation process was initiated by manually placing four points on the boundary of a selected slice, from which an initial prostate boundary was determined. This initial boundary was refined using the Discrete Dynamic Contour until it fit the actual prostate boundary. The remaining slices were then segmented by iteratively propagating this result to an adjacent slice and repeating the refinement, pausing the process when necessary to manually edit the boundary. The two methods were tested with six 3-D prostate images. The results showed that the parallel and rotational methods had mean editing rates of 20% and 14%, and mean (mean absolute) volume errors of -5.4% (6.5%) and -1.7% (3.1%), respectively. Based on these results, as well as the relative difficulty in editing, we conclude that the rotational segmentation method is superior. |
Title |
Semiparametric analysis of heterogeneous data using varying-scale generalized linear models. |
Author |
Xie M, Simpson DG, Carroll RJ. |
Journal |
Am Stat Assoc |
Volume |
|
Year |
2008 |
Abstract |
This article describes a class of heteroscedastic generalized linear regression models in which a subset of the regression parameters are rescaled nonparametrically, and develops efficient semiparametric inferences for the parametric components of the models. Such models provide a means to adapt for heterogeneity in the data due to varying exposures, varying levels of aggregation, and so on. The class of models considered includes generalized partially linear models and nonparametrically scaled link function models as special cases. We present an algorithm to estimate the scale function nonparametrically, and obtain asymptotic distribution theory for regression parameter estimates. In particular, we establish that the asymptotic covariance of the semiparametric estimator for the parametric part of the model achieves the semiparametric lower bound. We also describe bootstrap-based goodness-of-scale test. We illustrate the methodology with simulations, published data, and data from collaborative research on ultrasound safety. |
Title |
Semiparametric inference. |
Author |
He Z. |
Journal |
Thesis(PhD): Univ of Illinois |
Volume |
|
Year |
2010 |
Abstract |
Semi-parametric and nonparametric modeling and inference have been widely studies during the lat two decades. In this manuscript, we do statistical inference based on semi-parametric and nonparametric models in several different scenarios.Firstly, we develop a semi-parametric additivity test for nonparametric muti-dimensional model. The test statistic can test two or higher way interactions and achieve the biggest local power when the interaction terms have Tukey's format. Secondly, we develop a two step interactive estimating algorithm for generalized linear model with nonparametric varying dispersion. The algorithm is derived for heteroscedastic error generalized linear model, but it can be extended to more general setting for example censored data.Thirdly, we develop a multivariate intersection-union bioequivalence test. the intersection-union test is uniform more powerful compare with the common used test for mutivariate bioequivalence. Fourthly, we extend the multivariate bioquivalence test to functional dat, which can also be considered as high dimensional multivariate data. we develop two bioequivalence test based on L2 and L∞ norm. We illustrate the issues and methodology by both simulation and the context of ultrasound safety, back-scatter coefficient vs frequency study as well as a pharmacokinetics study.
|
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
|
|
|
|