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The optimization of ultrasonic contrast agent destruction for the assessment of blood perfusion.

机译：超声造影剂破坏的优化，用于评估血液灌注。

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摘要

Contrast-assisted perfusion estimation is accomplished by detecting contrast agent microbubbles as they are transported via blood vessels into a tissue of interest. Ultrasound contrast agent microbubbles can be destroyed with a destructive imaging mode, and then the inflow of new contrast agent microbubbles can be observed with a non-destructive imaging mode. Mean velocity, the time required for the echo intensity to reach 80% of the original intensity, and vascular density are estimated from the characteristic exponential rise of the received signal intensity from a perfused region of tissue. The imaging process requires three steps: contrast agent destruction, nondestructive detection, and parameter estimation.; The destruction threshold of contrast agent microbubbles is characterized experimentally in order to specify the optimal imaging conditions for the destructive imaging mode. The optimization of fragmentation as a function of imaging parameters and contrast agent resting radius suggests that small resting radius, high transmission pressure, and low transmission frequency increase the probability of destruction.; A novel non-destructive imaging mode is developed, based on subharmonic oscillations that can be generated in contrast agent microbubbles. Excellent contrast agent enhancement can be accomplished with subharmonic imaging, phase-inversion, and a wall filter, yielding a mean contrast agent-to-tissue ratio of 23 dB. Furthermore, subharmonic imaging can be generated in contrast agent microbubbles with imaging conditions that do not cause fragmentation.; A two-step estimation scheme is designed for estimating the initial value, the final value, and the slope of the characteristic rising exponential received echo intensity over time.; The destructive imaging mode, using high pressure and low frequency insonation, and the non-destructive imaging mode, using phase-inversion subharmonic imaging, are implemented on a Siemens Elegra scanner. An in-vitro experimental system is employed to compare the performance of the blood velocity estimator, as predicted by the model, with the performance observed experimentally. (Abstract shortened by UMI.)
机译：通过检测造影剂微泡，当造影剂微泡通过血管输送到目标组织中时，可以完成造影剂辅助的灌注估算。可以用破坏性成像模式破坏超声造影剂微泡，然后可以在非破坏性成像模式下观察新造影剂微泡的流入。平均速度，回波强度达到原始强度的80％所需的时间以及血管密度是根据来自组织灌注区域的接收信号强度的特征性指数上升来估算的。成像过程需要三个步骤：造影剂破坏，无损检测和参数估计。通过实验表征造影剂微泡的破坏阈值，以便为破坏性成像模式指定最佳成像条件。根据成像参数和造影剂静置半径对碎片的优化表明，较小的静置半径，较高的传输压力和较低的传输频率会增加破坏的可能性。基于可以在造影剂微泡中产生的亚谐波振荡，开发了一种新颖的非破坏性成像模式。亚谐波成像，相位反转和壁滤器可实现出色的造影剂增强效果，平均造影剂与组织之比为23 dB。此外，可以在造影剂微泡中产生亚谐波成像，其成像条件不会引起破裂。设计了两步估计方案，用于估计初始值，最终值以及特征上升指数接收回波强度随时间的斜率。在西门子Elegra扫描仪上实现了使用高压和低频声波的破坏性成像模式，以及使用相反转亚谐波成像的非破坏性成像模式。采用体外实验系统，以比较模型预测的血流速度估算器的性能与实验观察到的性能。 （摘要由UMI缩短。）

著录项

  • 作者

    Chomas, James Edmond.;

  • 作者单位

    University of Virginia.;

  • 授予单位 University of Virginia.;
  • 学科 Engineering Biomedical.; Health Sciences Radiology.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 171 p.
  • 总页数 171
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;预防医学、卫生学;
  • 关键词

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