Improved ultrasound imaging using elevated acoustic output

 描述(申请人提供)：超声波成像是美国最广泛使用的腹部成像方法之一。然而，据报道，在高达40%的患者中，超声图像质量对诊断不合格，这一挑战通常与肥胖有关。主要问题是缺乏穿透力和混响杂乱。我们假设，将机械指数(MI)从目前的1.9增加到2.4-3.4范围内，伴随着传输脉冲压力从40%增加到200%，将显著改善B型、谐波和多普勒图像质量。我们设计了这项提案，以专注于谐波成像。组织谐波成像(THI)是一种对混响杂波和离轴散射比基波成像更强的非线性成像方法，在改善超声成像质量方面取得了巨大的成功。然而，谐波信号电平比基波信号低15-20分贝，这就给DIF-fi患者的信噪比和深度穿透带来了挑战。诊断超声成像中使用的原位压力受到美国食品和药物管理局机械指数指南(MI&lt；1.9)事实上的上限的限制，该值是基于历史值，而不是与生物效应的科学证据fic联系在一起。在组织中没有 对于气体，只有在诊断频率和脉冲持续时间使用MI值大于5.0的情况下，才能报告基于空化的生物效应。美国超声医学研究所(AIUM)最近得出结论，如果在这一迄今未被探索的输出区域中的成像与相应的显著临床益处相关，则可以在不考虑无气体的非胎儿组织中增加空洞风险的情况下，证明超过FDA指南中推荐的最大MI达到原位估计值4.0时是合理的。我们已经获得了初步的活体数据，使用提升的MI谐波成像显示谐波信号水平增加了+20dB，穿透深度增加了40%，结构对比噪声比从12%-500%增加，从而使更多的结构能够可视化。这项工作的主要目标是优化提升的MI谐波图像质量，并量化由此产生的图像质量改善。fic的目标有3个：1)扩展我们的3D非线性模拟工具，对不同的组织属性和换能器fi曲线进行参数分析，以优化提升MI脉冲反转谐波成像中的谐波信号生成和图像质量，并确定在提升MI输出条件下水基估计和现场测量之间的关系。2)利用商用曲线腹部阵列和定制的大口径低频诊断阵列，在一台商用扫描仪上设计并实现了一个实时原型抬高MI系统。3)量化在计划进行腹部超声成像研究的患者以及已知有恶性肝脏肿块的患者中使用提升的mis所提供的成像性能的改善。

 DESCRIPTION (provided by applicant): Ultrasonic imaging is among the most widely used abdominal imaging modalities in the United States. However, ultrasonic image quality is reported to be insufficient for diagnosis in up to 40% of patients, a challenge often correlated with obesity. The major problems are lack of penetration and reverberation clutter. We hypothesize that increasing the Mechanical Index (MI) from the current limit of 1.9 to values in the 2.4-3.4 range, with concomitant transmit pulse pressure increases from 40 to 200%, will markedly improve B-mode, har- monic, and Doppler image quality. We have designed this proposal to focus on harmonic imaging. Tissue harmonic imaging (THI) is a nonlinear method that is more robust to reverberation clutter and off-axis scattering than fundamental imaging, and has found great success in improving ultrasonic image quality. However, har- monic signal levels are 15-20 dB lower than fundamental signals, which leads to challenges with signal-to-noise ratio and depth penetration in difficult-to-image patients. The in situ pressures used in diagnostic ultrasound imaging have been subject to a de facto upper limit established by the United States FDA guidelines for the Mechanical Index (MI<1.9), a value which is based upon historic values, rather than being linked to scientific evidence of bioeffects. In tissues without gas bodies, cavitation based bioeffects have only been reported at diagnostic frequencies and pulse durations using MI values greater than 5.0. The American Institute of Ul- trasound in Medicine (AIUM) recently concluded that exceeding the recommended maximum MI given in the FDA guidance up to an estimated in situ value of 4.0, could be warranted without concern for increased risk of cavitation in non-fetal tissues without gas bodies, if imaging in this heretofore unexplored output regime were associated with a corresponding significant clinical benefit. We have obtained preliminary in vivo data using elevated MI harmonic imaging demonstrating +20 dB increases in harmonic signal level, penetration depth increases of up to 40%, and structural contrast-to-noise ratio increases from 12-500%, enabling visualization of additional structures. The primary goals of this work are to optimize elevated MI harmonic image quality and to quantify the resulting image quality improvements. There are 3 specific aims: 1) To extend our 3D nonlinear simulation tools to perform a parametric analysis of varying tissue properties and transducer configurations to optimize harmonic signal generation and image quality in elevated MI pulse inversion har- monic imaging, and to determine the relationship between water-based estimates and in situ measurements in the elevated MI output regime. 2) To design and implement a real-time prototype elevated MI system using commercial curvilinear abdominal arrays and a custom designed prototype large aperture low frequency diag- nostic array on a commercial grade scanner. 3) To quantify improvements in imaging performance afforded by the use of elevated MIs in patients scheduled for ultrasonic abdominal imaging studies, and in patients known to have malignant liver masses.