基于振幅的回波模式声速层析成像
Amplitude-based echo-mode speed-of-sound tomography
AI总结：
该研究针对传统回波模式计算超声层析成像（CUTE）的空间分辨率受限及伪影问题，提出基于振幅的a-CUTE方法，模拟及体模、在体实验证实其分辨率提升与伪影减少的优势。
AI中文摘要：
组织的声速（SoS）是用于癌症或肝脂肪变性等疾病的无创零剂量诊断的有前景标志物。回波模式计算超声层析成像（CUTE）利用脉冲回波超声，通过分析不同发射和接收偏转角度对探测时的回波变化来获取空间分辨的SoS。传统分析聚焦于回波相移，将其解释为差分飞行时间（dToF）并与SoS关联。尽管已取得有前景的结果，但波束宽度与角孔径的权衡不仅限制了空间分辨率，还会在具有短尺度SoS变化的介质中产生伪影噪声。为克服此局限，我们提出一种替代方法：对每个回波，不将角度相关变化简化为单一参数（dToF），而是通过反演将像差轮廓与所有角度对检测到的回波振幅关联的模型，获取亚波束宽度分辨率的像差轮廓。我们在模拟中证明，与dToF-CUTE相比，这种基于振幅的（a-CUTE）方法可显著提升空间分辨率并减少伪影。物理体模及初步在体结果证实了该新方法在实际数据中的可行性。
英文摘要：
The tissue's speed of sound (SoS) is a promising marker for non-invasive and zero-dose diagnosis of diseases such as cancer or liver steatosis. Computed ultrasound tomography in echo mode (CUTE) retrieves spatially resolved SoS using pulse-echo ultrasound, by analysing the variation of echoes when probed with varying pairs of transmit- and receive-steering angles. This analysis conventionally focuses on the echo phase shift, which is interpreted as differential time-of-flight (dToF) and related to SoS. While promising results have been obtained, the trade-off between beamwidth and angular aperture not only limits spatial resolution but also leads to artefactual noise in media with short-scale SoS variations. To overcome this limitation, we propose an alternative approach: for each echo, instead of reducing the angle-dependent variations to a single parameter (the dToF), we retrieve aberration profiles with sub-beamwidth resolution by inverting a model that relates these profiles to the echo amplitudes detected for all angle pairs. We demonstrate in simulations that this amplitude-based (a-CUTE) approach results in substantially improved spatial resolution and reduced artifacts compared to dToF-CUTE. Physical phantom and preliminary in vivo results confirm the feasibility of this novel method in physical data.
