Visualizing the Radial and Circumferential Strain Distribution Within Vessel Phantoms Using Synthetic-Aperture Ultrasound Elastography
Visualizing the Radial and Circumferential Strain Distribution Within Vessel Phantoms Using Synthetic-Aperture Ultrasound Elastography
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DOI：
10.1109/tuffc.2012.2370
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发表时间：
2012-08-01
影响因子：
3.6
通讯作者：
Doyley, Marvin M.
中科院分区：
文献类型：
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作者：
Korukonda, Sanghamithra;Doyley, Marvin M.
无创弹性成像 (NIVE) 生成的弹性图难以解释，因为 NIVE 将传感器坐标系中的应变可视化。在本文中，我们假设将法向应变弹性图和剪切应变弹性图转换到血管坐标系将产生更好的应变弹性图。为了证实这一假设，我们从模拟和物理血管模型中获取了合成孔径 (SA) 超声数据。在这两项研究中，SA 回波帧都是根据稀疏换能器阵列采集的数据重建的。模拟研究是使用同质和异质体模进行的，但在实验研究中，我们使用改进的超声扫描仪从同质（n = 1）和异质（n = 3）血管体模获取SA数据。通过对波束形成的射频回波帧进行二维互相关分析来估计轴向和横向位移。我们通过将法向应变弹性图和剪切应变弹性图转换到血管坐标系来生成径向和周向应变弹性图。结果表明：1）从模拟数据获得的径向和周向应变弹性图的相对均方根误差约为0.1％； 2) 实验采集的径向和周向应变弹性图的弹性成像对比噪声比 (CNRe) 在 10 到 40 dB 之间，弹性成像信噪比 (SNRe) 在 10 到 35 dB 之间，具体取决于成像过程中使用的主动传输元件的数量； 3) 使用少于 8 个主动传输元件生成的径向和周向应变弹性图不如使用更多数量的主动传输元件计算的结果； 4) 除了使用最稀疏换能器阵列获得的斑块之外，应变弹性图中斑块很明显。这项研究表明，合成孔径超声系统可以无创地可视化径向和周向应变。
Noninvasive elastography (NIVE) produces elastograms that are difficult to interpret because NIVE visualizes strain in the transducer coordinate system. In this paper, we hypothesized that transforming normal and shear strain elastograms to the vessel coordinate system will produce better strain elastograms. To corroborate this hypothesis, we acquired synthetic-aperture (SA) ultrasound data from simulated and physical vessel phantoms. In both studies, SA echo frames were reconstructed from data acquired with a sparse transducer array. The simulation study was performed with homogeneous and heterogenous phantoms, but in the experimental study we used a modified ultrasound scanner to acquire SA data from homogeneous (n = 1) and heterogeneous (n = 3) vessel phantoms. Axial and lateral displacements were estimated by performing two-dimensional cross-correlation analysis on the beamformed RF echo frames. We generated radial and circumferential strain elastograms by transforming normal and shear strain elastograms to the vessel coordinate system. The results revealed: 1) radial and circumferential strain elastograms acquired from simulated data had a relative root mean squared error on the order of 0.1%; 2) experimentally acquired radial and circumferential strain elastograms had elastographic contrast-to-noise ratio (CNRe) between 10 and 40 dB, and elastographic signal-to-noise ratio (SNRe) between 10 and 35 dB, depending on the number of active transmission elements employed during imaging; 3) radial and circumferential strain elastograms produced with fewer than 8 active transmission elements were inferior to those computed with a greater number of active elements; and 4) plaques were evident in the strain elastograms, except in those obtained with the sparsest transducer array. This study demonstrated that a synthetic-aperture ultrasound system could visualize radial and circumferential strain noninvasively.