Method for the estimation and compensation of attenuating tissue layers by the acoustic observation of microbubbles for sonoporation therapy
Method for the estimation and compensation of attenuating tissue layers by the acoustic observation of microbubbles for sonoporation therapy
复制标题
用于声孔治疗的微泡声学观察估计和补偿衰减组织层的方法
DOI：
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
G. Schmitz
中科院分区：
文献类型：
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作者：
K. Hensel;G. Schmitz
超声穿孔的成功与否，即由于与微泡（MB）的相互作用而使细胞膜通透性瞬间增加，在很大程度上取决于声激励的参数。低的压力振幅导致低的声穿孔率，而高的压力振幅导致大量的死细胞。然而，由于组织衰减，治疗部位的压力不能可靠地预测。因此，我们提出了一种利用MB破坏的声学观测来估计和补偿衰减组织的新方法。声波分解过程中重复的MB失谐导致连续的MB破坏。将简化的微波破坏模型拟合到次谐波功率衰减中，提取微波破坏的特征时间常数。对于一系列焦点压力，这些时间常数由校准测量产生，以获得特征曲线。该特性曲线可用于估计和补偿中间组织层的衰减。为了验证该方法，使用Sonovue MB解决方案将单元件换能器的焦点放在流道上。第一步，在中心频率3.3 MHz的条件下，将焦点压力在150 kPa ~ 760 kPa之间变化，生成特征曲线。这些激发参数以前已被用于成功的超声治疗。第二步，在传感器和MB之间放置衰减乳胶层（2.4 dB和3.8 dB）。根据特性曲线，衰减估计为2.2 dB和4.6 dB，均方根误差（RMSE）为7.1%。衰减通过增加初始压力幅值通过逆估计衰减因子来补偿，以获得所需的MB行为。比较期望的和得到的特征时间常数，RMSE为22.9%。实验结果验证了所提方法的正确性。误差是由流动通道中MB浓度的不恒定和由于衰减的频率依赖性而改变的治疗脉冲引起的。通过采用所提出的方法，超声穿孔治疗的激发幅度可以自适应地增加以补偿组织衰减，从而产生最佳超声穿孔率所需的MB行为。在超声治疗期间进一步的在线监测将允许调节兴奋参数。
The success of sonoporation, the transient increase of cell membrane permeability due to the interaction with microbubbles (MB), strongly depends on the parameters of the acoustic excitation. Low pressure amplitudes result in a low sonoporation rate, whereas high pressure amplitudes cause high numbers of dead cells. However, due to tissue attenuation the pressure at the therapy site cannot be predicted reliably. Consequently, we present a new method for the estimation and compensation of attenuating tissue by the acoustic observation of MB destruction. Repetitive MB insonification during sonoporation causes successive MB destruction. A simplified model for MB destruction is fitted to the subharmonic power decay to extract characteristic time constants for MB destruction. For a range of focal pressures, these time constants are generated from calibration measurements to obtain a characteristic curve. This characteristic curve can be employed to estimate and compensate the attenuation of intermediate tissue layers. To validate this method, the focus of a single element transducer is placed on a flow channel with Sonovue MB solution. In a first step, the characteristic curve is generated by varying the focal pressure between 150 kPa and 760 kPa with a central frequency of 3.3 MHz. These excitation parameters have been employed for successful sonoporation therapy before. In a second step, attenuating latex layers (2.4 dB and 3.8 dB) were placed between transducer and MB. Based on the characteristic curve, the attenuation was estimated to be 2.2 dB and 4.6 dB, resulting in a root mean squared error (RMSE) of 7.1%. The attenuation was compensated by increasing the initial pressure amplitude by the inverse estimated attenuation factor in order to obtain the desired MB behavior. Comparing the desired and the resulting characteristic time constant, a RMSE of 22.9% was obtained. The results verify the proposed method. Errors are caused by inconstant MB concentration in the flow channel and an altered therapy pulse due to the frequency dependency of the attenuation. By employing the proposed method, the excitation amplitude for sonoporation therapy can be adaptively increased to compensate tissue attenuation, yielding the desired MB behavior for the optimal sonoporation rate. Further online monitoring during sonoporation therapy would allow the adjustment of excitation parameters.
影响因子：
20.1
作者：
JAYAWEERA, AR;EDWARDS, N;KAUL, S
通讯作者：
KAUL, S
影响因子：
2.9
作者：
Azencott, Harold R.;Peter, Gary F.;Prausnitz, Mark R.
通讯作者：
Prausnitz, Mark R.