IEEE Trans Ultrason Ferroelectr Freq Control. 2021 May;68(5):1721-1728. doi: 10.1109/TUFFC.2021.3050481. Epub 2021 Apr 26.
Contrast-enhanced ultrasound (CEUS) is a real-time imaging technique that allows the visualization of organ and tumor microcirculation by utilizing the nonlinear response of microbubbles. Nonlinear pulsing schemes are used exclusively in CEUS imaging modes in modern scanners. One important aspect of nonlinear pulsing schemes is the near-complete elimination of the linear signals that originate from tissue. Up until now, no study has investigated the performance of Verasonics scanners in eliminating the linear signals during CEUS and, by extension, the optimal pulsing sequences for performing CEUS. The aim of this article was to investigate linear signal cancellation of the Verasonics scanner performing nonlinear pulsing schemes with two different probes (L7-4 linear array and C5-2 convex array). We have considered two pulsing schemes: pulse inversion (PI) and amplitude modulation (AM). We have also compared our results from the Verasonics scanner with a clinical scanner (Philips iU22). We found that the linear signal cancellation of the transmitted pulse by Verasonics scanner was ~40 dB in AM mode and ~30 dB in PI mode when operated at 0.06 MI. The linear signal cancellation performance of Verasonics scanner was comparable with Philips iU22 scanner in focused AM mode and on average 3 dB better than Philips iU22 scanner in focused PI mode.
对比增强超声（CEUS）是一种实时成像技术，通过利用微泡的非线性响应，可以可视化器官和肿瘤的微循环。非线性脉冲方案仅在现代扫描仪的 CEUS 成像模式中使用。非线性脉冲方案的一个重要方面是几乎完全消除了源自组织的线性信号。到目前为止，还没有研究调查 Verasonics 扫描仪在 CEUS 期间消除线性信号的性能，以及执行 CEUS 的最佳脉冲序列。本文的目的是研究 Verasonics 扫描仪在使用两种不同探头（L7-4 线性阵列和 C5-2 凸阵）执行非线性脉冲方案时的线性信号消除情况。我们考虑了两种脉冲方案：脉冲反转（PI）和振幅调制（AM）。我们还将 Verasonics 扫描仪的结果与临床扫描仪（Philips iU22）进行了比较。我们发现，Verasonics 扫描仪在 0.06 MI 时以 AM 模式操作时，其发射脉冲的线性信号消除约为 40 dB，而在 PI 模式时约为 30 dB。Verasonics 扫描仪的线性信号消除性能与飞利浦 iU22 扫描仪在聚焦 AM 模式下相当，而在聚焦 PI 模式下平均比飞利浦 iU22 扫描仪好 3 dB。
