|
|
|
BRL Abstracts Database |
|
Your search for ultrasound produced 3296 results. Page 109 out of 330
| Title |
Effects of ultrasound on the steady-state transmembrane pH gradient and the permeability of acetic acid through bilayer lipid membranes. |
| Author |
Pohl P, Rosenfeld E, Millner R. |
| Journal |
Biochim Biophys Acta |
| Volume |
|
| Year |
1993 |
| Abstract |
The irradiation of bilayer lipid membranes with continuous ultrasound of a frequency of 8.2 MHz and a spacial peak time average (SPTA) intensity of 0.4 W/cm2 reduces the thickness of the unstirred layer up to 40% of its initial value under our conditions. This result was obtained from measurements of the transmembrane potential which appears after the addition of a protonophore in the presence of a gradient of acetic acid. Ultrasound exposure decreases this potential when the pH of the buffer solutions is much higher than the pK of CH3COOH and has no effect at low pH values. The latter can be explained by a simultaneous increase of the permeability of acetic acid and the buffer substances, respectively, due to ultrasound irradiation |
| Title |
Effects of ultrasound. |
| Author |
Lehmann, Biegler |
| Journal |
Book Chapter |
| Volume |
|
| Year |
1954 |
| Abstract |
No abstract available. |
| Title |
Effects on mature mouse oocytes of ultrasound treatment applied before in vitro fertilisation. |
| Author |
Puissant F, Lejeune B, Leroy F. |
| Journal |
IRCS J Med Sci |
| Volume |
|
| Year |
1984 |
| Abstract |
Although diagnostic ultrasound is currently used for assessing follicular growth (1-3) and for oocyte retrieval (4, 5), little attention has been paid to the possible consequences of this treatment on oocytes and to their development after fertilisation (6-8). We have therefore investigated the effects of applying pulse ultrasound to superovulated mouse oocytes under conditions similar to those used for clinical purposes. The results were evaluated in terms of the in vitro fertilisation rate, the percentage and speed of early development and the proportion of embryos implanted after transfer to pseudopregnant females. |
| Title |
Efficacy of sonothrombolysis in a rat model of embolic ischemic stroke. |
| Author |
Daffertshofer M, Huang Z, Fatar M, Popolo M, Schroeck H, Kuschinsky W, Moskowitz MA, Hennerici MG. |
| Journal |
Neuroscience Letters |
| Volume |
|
| Year |
2004 |
| Abstract |
The key goal in the treatment of acute ischemic stroke is fast vessel recanalization. Thrombolysis with recombinant tissue plasminogen activator (rt-PA) is efficient in humans but mean time for recanalization is within hours. Ultrasound bio-effects has been shown to facilitate rt-PA mediated thrombolysis in peripheral arteries. We used an embolic stroke model in the rat. In all rats we induced an ischemic stroke by a selective occlusion of the middle cerebral artery with whole blood clots. From an entire collective of 54 rats 47 completed the protocol (n=7 died early). Four different groups (no treatment n=6; full dose rt-PA treatment only [10 mg/kg per body weight] n=14, half dose rt-PA treatment plus ultrasound n=10, and full dose rt-PA treatment plus ultrasound n=17) were investigated. We found a significant reduction of absolute as well as relative infarct volume in the full dose rt-PA plus ultrasound group (81?72 mm3; P<0.05) in comparison to untreated rats (253?159 mm3; P<0.05) as well as in comparison to rats treated with full dose rt-PA only (167?91 mm3; P<0.05). There were five intracranial bleedings giving a bleeding rate of 9.3%. In summary: ultrasound treatment in addition to rt-PA is more effective than single rt-PA treatment in reducing infarct volume and safe with regard to bleeding. |
| Title |
Efficient array beam forming by spatial filtering for ultrasound B-mode imaging. |
| Author |
Kim KS, Insana MF. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2006 |
| Abstract |
This paper proposes an efficient array beam-forming method using spatial matched filtering (SMF) for ultrasonic imaging. In the proposed method, ultrasonic waves are transmitted from an array subaperture with fixed transmit focus as in conventional array imaging. At receive, radio frequency echo signals from each receive channel are passed through a spatial matched filter that is constructed based on the system transmit-receive spatial impulse response. The filtered echo signals are then summed without time delays. The filter concentrates and spatially registers the echo energy from each element so that the pulse-echo impulse response of the summed output is focused with acceptably low side lobes. Analytical beam pattern analysis and simulation results using a linear array show that this spatial filtering method can improve lateral resolution and contrast-to-noise ratio as compared with conventional dynamic receive focusing (DRF) methods. Experimental results with a linear array are consistent but point out the need to address additional practical issues. Spatial filtering is equivalent to synthetic aperture methods that dynamically focus on both transmit and receive throughout the field of view. In one common example of phase aberrations, the SMF method was degraded to a degree comparable to conventional DRF methods. |
| Title |
Efficient array beam forming by spatial filtering for ultrasound B-mode imaging. |
| Author |
Kim KS, Liu J, Insana MF. |
| Journal |
J Acoust Soc Am |
| Volume |
|
| Year |
2003 |
| Abstract |
This paper proposes an efficient array beam-forming method using spatial matched filtering (SMF) for ultrasonic imaging. In the proposed method, ultrasonic waves are transmitted from an array subaperture with fixed transmit focus as in conventional array imaging. At receive, radio frequency echo signals from each receive channel are passed through a spatial matched filter that is constructed based on the system transmit-receive spatial impulse response. The filtered echo signals are then summed without time delays. The filter concentrates and spatially registers the echo energy from each element so that the pulse-echo impulse response of the summed output is focused with acceptably low side lobes. Analytical beam pattern analysis and simulation results using a linear array show that this spatial filtering method can improve lateral resolution and contrast-to-noise ratio as compared with conventional dynamic receive focusing (DRF) methods. Experimental results with a linear array are consistent but point out the need to address additional practical issues. Spatial filtering is equivalent to synthetic aperture methods that dynamically focus on both transmit and receive throughout the field of view. In one common example of phase aberrations, the SMF method was degraded to a degree comparable to conventional DRF methods. |
| Title |
Efficient convolution kernels for computerized tomography. |
| Author |
Kenue SK, Greenleaf JF. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
1979 |
| Abstract |
Three concepts are presented: 1) Extended kernels: The Ramachandran-Lakshminarayanan convolution kernel has one zero between each non-zero value in the spatial domain. By extending the kernel in Fourier space, it is shown that each extension leads to two additional zeros in the spatial domain of the convolution kernel, thus decreasing the required number of multiplications necessary for convolution. Any known kernel can be extended and in the limit of extension a simple backprojection reconstruction is obtained. 2) Binary kernels: A technique for generating binary approximations to any convolution kernel is described. Excluding the central element, all other elements of the kernel are approximated by an even power of two; thus, multiplications are replaced by shift operations in the convolution procedure. 3) Recursive convolution: It is shown how additions can be saved by using a recursive formulation which generates new elements in the convolution procedure utilizing only a few summation steps. Results from both extended kernels and their binary approximations are described for simulated phantoms and ultrasound data obtained from breast scans of patients. |
| Title |
Einfache Ultrashall-Resonatoren zur Messung von Dampfung und Geschwindigkeit unter 100 kHz in Milliliter-Flussigkeitsproben. (Simple ultrasound resonators for measurement of attenuation rate below 100 kHz in milliliter liquid samples.) -Article is in Ge |
| Author |
Eggers F, Richmann KH. |
| Journal |
Forschr Akust - FASE/DAGA |
| Volume |
|
| Year |
1994 |
| Abstract |
No abstract available. |
| Title |
Elastographic characterization of HIFU-induced lesions in canine livers. |
| Author |
Rightetti R, Kallel F, Stafford RJ, Price RE, Krouskop TA, Hazle JD, Ophir J. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1999 |
| Abstract |
The elastographic visualization and evaluation of high-intensity focused ultrasound (HIFU)-induced lesions were investigated. The lesions were induced in vitro in freshly excised canine livers. The use of different treatment intensity levels and exposure times resulted in lesions of different sizes. Each lesion was clearly depicted by the corresponding elastogram as being an area harder than the background. The strain contrast of the lesion/background was found to be dependent on the level of energy deposition. A lesion/background strain contrast between -2.5 dB and -3.5 dB was found to completely define the entire zone of tissue damage. The area of tissue damage was automatically estimated from the elastograms by evaluating the number of pixels enclosed inside the isointensity contour lines corresponding to a strain contrast of -2.5, -3 and -3.5 dB. The area of the lesion was measured from a tissue photograph obtained at approximately the same plane where elastographic data were collected. The estimated lesion areas ranged between approximately 10 mm2 and 110 mm2. A high correlation between the damaged areas as depicted by the elastograms and the corresponding areas as measured from the gross pathology photographs was found (r2 = 0.93, p value < 0.0004, n = 16). This statistically significant high correlation demonstrates that elastography has the potential to become a reliable and accurate modality for HIFU therapy monitoring. |
| Title |
Elastographic imaging of thermal lesions in soft tissue: A preliminary study in vitro. |
| Author |
Stafford RJ, Kallel F, Price RE, Cromeens DM, Krouskop TA, Hazle JD, Ophir J. |
| Journal |
Ultrasound Med Biol |
| Volume |
|
| Year |
1998 |
| Abstract |
The use of elastography for the visualization of thermal lesions in biological soft tissue in vitro was investigated. Thermal lesions were created in samples of postmortem ovine kidney using a surgical neodymium: YAG (Nd:YAG) laser. The kidney samples were cast in gel, and elastographic images of the lesions were constructed using sonographic information and external markers to locate the region of interest. Gross pathology of the kidney samples confirmed the dimensions of the lesions. Good correlation between the lesion length along the laser fiber axis and maximum diameter measured off of the fiber axis determined from elastographic images and gross pathology photographs was found. |
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
|
|
|
|
