Transmit beamforming has a strong impact on several factors that govern image quality, field-of-view, and frame-rate in ultrasound imaging. For cardiac applications, the visualization of fine structures and the ability to track their motion is equally important. Consequently, beamforming choices for echocardiography aim to optimize these trade-offs. Acoustic clutter can dramatically impact image quality and degrade the diagnostic value of cardiac ultrasound imaging. Clutter levels, however, are closely tied to the choice of beamforming configuration. This study aims to quantify the impact of transmit beamforming on clutter levels under in vivo conditions. The performance of focused as well as plane wave transmit configurations in fundamental and harmonic modes is evaluated under matched conditions. Contrast between the cardiac chambers and the interventricular septum is used as a surrogate for the level of clutter in a given imaging scenario. Under in vivo conditions, contrast was found to improve incrementally across the four beamforming configurations in the following order: fundamental-plane, fundamental-focused, harmonic-plane, and harmonic-focused. Using the fundamental-focused configuration as a reference, the harmonic-plane and harmonic-focused cases showed improvements in median contrast of 2.97 dB and 6.1 dB, respectively, while the fundamental-plane case showed a contrast deterioration of 1.23 dB. Contrast was also found to vary systematically as a function of imaging depth. Median contrast for the right ventricle (shallow chamber) was measured to be 2.96 dB lower than that in the left ventricle (deep chamber).

中文翻译：

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发射波束形成对经胸超声心动图杂波水平的影响


发射波束成形对控制超声成像中的图像质量、视场和帧速率的多个因素有很大影响。对于心脏应用，精细结构的可视化和跟踪其运动的能力同样重要。因此，超声心动图的波束形成选择旨在优化这些权衡。声学杂波会极大地影响图像质量并降低心脏超声成像的诊断价值。然而，杂波水平与波束形成配置的选择密切相关。本研究旨在量化体内条件下发射波束成形对杂波水平的影响。在匹配条件下评估基波和谐波模式下的聚焦波和平面波发射配置的性能。心室和室间隔之间的对比度被用作给定成像场景中杂波水平的替代指标。在体内条件下，发现四种波束形成配置的对比度按以下顺序逐渐改善：基波平面、基波聚焦、谐波平面和谐波聚焦。使用基波聚焦配置作为参考，谐波平面和谐波聚焦情况的中值对比度分别提高了 2.97 dB 和 6.1 dB，而基波平面情况的对比度恶化了 1.23 dB。还发现对比度作为成像深度的函数而系统地变化。测得右心室（浅室）的中位对比度比左心室（深室）低 2.96 dB。