The development of adaptive imaging techniques is contingent on the accurate and repeatable characterization of ultrasonic image quality. Adaptive transmit frequency selection, filtering, and frequency compounding all offer the ability to improve target conspicuity by balancing the effects of imaging resolution, the signal-to-clutter ratio, and speckle texture, but these strategies rely on the ability to capture image quality at each desired frequency. We investigate the use of broadband linear frequency-modulated transmissions, also known as chirps, to expedite the interrogation of frequency-dependent tissue spatial coherence for real-time implementations of frequency-based adaptive imaging strategies. Chirp-collected measurements of coherence are compared to those acquired by individually transmitted conventional pulses over a range of fundamental and harmonic frequencies, in order to evaluate the ability of chirps to recreate conventionally acquired coherence. Simulation and measurements in a uniform phantom free of acoustic clutter indicate that chirps replicate not only the mean coherence in a region-of-interest but also the distribution of coherence values over frequency. Results from acquisitions in porcine abdominal and human liver models show that prediction accuracy improves with chirp length. Chirps are also able to predict frequency-dependent decreases in coherence in both porcine abdominal and human liver models for fundamental and pulse inversion harmonic imaging. This work indicates that the use of chirps is a viable strategy to improve the efficiency of variable frequency coherence mapping, thus presenting an avenue for real-time implementations for frequency-based adaptive strategies.

中文翻译：

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传统和线性调频传输中的频率相关空间相干性

自适应成像技术的发展取决于超声图像质量的准确和可重复表征。自适应发射频率选择，滤波和频率合成都可以通过平衡成像分辨率，信噪比和斑点纹理的影响来提高目标显着性，但是这些策略依赖于在以下情况下捕获图像质量的能力：每个所需的频率。我们研究了宽带线性调频传输（也称为线性调频）的使用，以加快基于频率的组织空间相干性的询问，以实现基于频率的自适应成像策略的实时实现。将rp收集的相干性测量值与在一定范围的基频和谐波频率上通过单独传输的常规脉冲获得的相干性测量结果进行比较，以评估of产生的常规相干性的能力。在没有声杂波的统一体模中进行的仿真和测量表明，chi不仅复制了感兴趣区域中的平均相干，而且还复制了相干值在频率上的分布。猪腹部和人肝模型的采集结果表明，prediction的长度会提高预测的准确性。fundamental还能够预测猪腹部和人肝脏模型中相干的频率依赖性降低，以进行基本和脉冲反转谐波成像。