Lag-One Coherence as a Metric for Ultrasonic Image Quality
Lag-One Coherence as a Metric for Ultrasonic Image Quality
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DOI：
10.1109/tuffc.2018.2855653
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发表时间：
2018-10-01
影响因子：
3.6
通讯作者：
Trahey, Gregg E.
中科院分区：
文献类型：
--
作者：
Long, Will;Bottenus, Nick;Trahey, Gregg E.
在复杂的成像环境中，例如在体内遇到的成像环境中，可靠地评估图像质量是一项重要但具有挑战性的任务。为了解决这一挑战，我们提出了一种新的成像度量，称为滞后一相干性（lag-one coherency，缩写为ECOMM），它利用最近邻阵列元素之间的空间相干性来提供热噪声和声噪声的局部测量。在本文中，我们推导出的理论，相关的对比度和对比度噪声比（CNR）的传统图像质量指标的通道噪声。仿真和幻影的研究进行验证这一理论，并比较的变异性，传统的度量。我们进一步评估的性能，匹配测量对比度，CNR，和时间相关性，从体内肝脏图像形成不同的机械指数（MI），以评估自适应声输出选择的可行性，使用声反馈。模拟和体模结果显示，在广泛的临床相关噪声水平范围内，相对于造影剂和CNR，EVR的变异性较低。与对比度和CNR的匹配测量值（分别为88.6%和85.7%的采集）相比，体内测量结果显示MI变化的单调性增加，这一稳定性得到了体内测量结果的支持。在没有热噪声的情况下，在高声学输出水平下，噪声强度与对比度（r = 0.74）和噪声强度与CNR（r = 0.66）之间的正相关性证明了噪声强度对稳态声学噪声的敏感性。结果表明，超声心动图提供了可重复的表征患者特定的图像质量趋势，证明了使用超声心动图选择声输出的可行性及其在体内图像质量评估中的应用。
Reliable assessment of image quality is an important but challenging task in complex imaging environments such as those encountered in vivo. To address this challenge, we propose a novel imaging metric, known as the lag-one coherence (LOC), which leverages the spatial coherence between nearest-neighbor array elements to provide a local measure of thermal and acoustic noise. In this paper, we derive the theory that relates LOC and the conventional image quality metrics of contrast and contrast-to-noise ratio (CNR) to channel noise. Simulation and phantom studies are performed to validate this theory and compare the variability of LOC to that of conventional metrics. We further evaluate the performance of LOC using matched measurements of contrast, CNR, and temporal correlation from in vivo liver images formed with varying mechanical index (MI) to assess the feasibility of adaptive acoustic output selection using LOC feedback. Simulation and phantom results reveal a lower variability in LOC relative to contrast and CNR over a wide range of clinically relevant noise levels. This improved stability is supported by in vivo measurements of LOC which show an increased monotonicity with changes in MI compared to matched measurements of contrast and CNR (88.6% and 85.7% of acquisitions, respectively). The sensitivity of LOC to stationary acoustic noise is evidenced by positive correlations between LOC and contrast (r = 0.74) and LOC and CNR (r = 0.66) at high acoustic output levels in the absence of thermal noise. Results indicate that LOC provides repeatable characterization of patient-specific trends in image quality, demonstrating feasibility in the selection of acoustic output using LOC and its application for in vivo image quality assessment.