کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1761252 | 1019639 | 2007 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Attenuation and Size Distribution Measurements of Definity⢠and Manipulated Definity⢠Populations
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
آکوستیک و فرا صوت
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Attenuation and Size Distribution Measurements of Definity⢠and Manipulated Definity⢠Populations Attenuation and Size Distribution Measurements of Definity⢠and Manipulated Definity⢠Populations](/preview/png/1761252.png)
چکیده انگلیسی
The contrast agent Definity⢠has recently been shown to have substantial nonlinear activity at high ultrasound frequencies (>10 MHz). In this study, measurements were performed to characterize the frequency dependant attenuation properties of Definity⢠and populations of Definity⢠that had been modified to preferentially isolate smaller bubbles through decantation or mechanical filtration. A narrowband pulse-echo substitution method was employed with a series of four transducers covering the frequency range from 2 to 50 MHz. “Native” Definity⢠has peak in attenuation in the vicinity of 10 MHz and remains high until 50 MHz. This pattern is significantly different from other clinically approved agents and is consistent with recent reports of nonlinear activity at high frequencies. With increasing decantation times, the attenuation peak becomes more diffuse and occurs at progressively higher frequencies. By 3 h for example, attenuation continues to rise until 30 MHz. The bubble size distribution undergoes preferential skewing toward smaller bubbles with increasing decantation time. Between 30 s and 3 h, the mean bubble diameter goes from 3.99 to 0.98 micrometers. Mechanical filtration with 2 and 1 μm pores causes attenuation to rise until 15 and 40 MHz, respectively. Definity⢠can therefore be manipulated to improve its relative activity at higher frequencies (>10 MHz), which has implications for ultrasound biomicroscopy and intravascular ultrasound applications. Further, these results suggest that agent handling can have a substantial impact on size distributions affecting lower frequency applications. Shell friction estimates derived from these data are lower than those reported for larger bubbles at lower frequencies. (E-mail: goertz@sri.sunnybrook.utoronto.ca)
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ultrasound in Medicine & Biology - Volume 33, Issue 9, September 2007, Pages 1376-1388
Journal: Ultrasound in Medicine & Biology - Volume 33, Issue 9, September 2007, Pages 1376-1388
نویسندگان
David E. Goertz, Nico de Jong, Antonius F.W. van der Steen,