Influence of shell properties on high-frequency ultrasound imaging and drug delivery using polymer-shelled microbubbles.
Influence of shell properties on high-frequency ultrasound imaging and drug delivery using polymer-shelled microbubbles.
复制标题
DOI：
10.1109/tuffc.2013.2537
复制
发表时间：
2013-01
期刊：
影响因子：
--
通讯作者：
Ketterling JA
中科院分区：
文献类型：
--
作者：
Chitnis PV;Koppolu S;Mamou J;Chlon C;Ketterling JA
本研究分为两部分，研究了静态超压条件下超声造影剂（UCA）的外壳破裂和20 MHz短脉冲群下UCA的次谐波成分。在甘油填充的试验箱中，对壳厚径比（STRR）为7.5、30、40、65和100 nm/μm的五种不同聚乳酸壳UCA进行静态超压试验。视频显微镜成像的UCAs的压力从2到330千帕超过90分钟。图像进行后处理，以获得破裂的压力阈值和单个微泡的直径。通过使稀释的UCA溶液流过放置在20 MHz换能器的几何焦点处的无壁流动体模，研究了单个UCA的后向散射。UCA进行了10- 20周期的音爆的声压范围从0.3到2.3 MPa。基于奇异值分解（SVD）的方法，以获得一个累积的次谐波得分（SHS）。不同的UCA类型表现出明显不同的破裂阈值，线性相关的STRR，但不相关的UCA大小。STRR = 100 nm/μm的UCA的破裂阈值比STRR = 7.5 nm/μm的UCA大4倍以上。聚合物壳UCA产生大量的次谐波响应，但20 MHz的激励的次谐波响应与STRR或UCA破裂压力无关。20个周期的激励导致SHS是用10个周期的短纯音激励的UCA的2至3倍。
This two-part study investigated shell rupture of ultrasound contrast agents (UCAs) under static overpressure conditions and the subharmonic component from UCAs subjected to 20-MHz tonebursts. Five different polylactide-shelled UCAs with shell-thickness-to-radius ratios (STRRs) of 7.5, 30, 40, 65, and 100 nm/μm were subjected to static overpressure in a glycerol-filled test chamber. A video microscope imaged the UCAs as pressure varied from 2 to 330 kPa over 90 min. Images were postprocessed to obtain the pressure threshold for rupture and the diameter of individual microbubbles. Backscatter from individual UCAs was investigated by flowing a dilute UCA solution through a wall-less flow phantom placed at the geometric focus of a 20-MHz transducer. UCAs were subjected to 10- and 20-cycle tonebursts of acoustic pressures ranging from 0.3 to 2.3 MPa. A method based on singular-value decomposition (SVD) was employed to obtain a cumulative subharmonic score (SHS). Different UCA types exhibited distinctly different rupture thresholds that were linearly related to their STRR, but uncorrelated with UCA size. The rupture threshold for the UCAs with an STRR = 100 nm/μm was more than 4 times greater than the UCAs with an STRR = 7.5 nm/μm. The polymer-shelled UCAs produced substantial subharmonic response but the subharmonic response to 20-MHz excitation did not correlate with STRRs or UCA-rupture pressures. The 20-cycle excitation resulted in an SHS that was 2 to 3 times that of UCAs excited with 10-cycle tonebursts.