Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden. Department of Clinical Sciences, Karolinska Institutet, Stockholm, Sweden. Author to whom any correspondence should be addressed.
Phys Med Biol. 2018 Nov 23;63(23):235008. doi: 10.1088/1361-6560/aaec2b.
Ultrasound elastography has shown potential for improved plaque risk stratification. However, no clear consensus exists on what output metric to use, or what imaging parameters would render optimal plaque differentiation. For this reason we developed a combined ex vivo and in vitro setup, in which the ability to differentiate phantom plaques of varying stiffness was evaluated as a function of plaque geometry, push location, imaging plane, and analysed wave speed metric. The results indicate that group velocity or phase velocity ⩾1 kHz showed the highest ability to significantly differentiate plaques of different stiffness, successfully classifying a majority of the 24 analysed plaque geometries, respectively. The ability to differentiate plaques was also better in the longitudinal views than in the transverse view. Group velocity as well as phase velocities <1 kHz showed a systematic underestimation of plaque stiffness, stemming from the confined plaque geometries, however, despite this group velocity analysis showed lowest deviation in estimated plaque stiffness (0.1 m s compared to 0.2 m s for phase velocity analysis). SWE results were also invariant to SWE push location, albeit apparent differences in signal-to-noise ratio (SNR) and generated plaque particle velocity. With that, the study has reinforced the potential of SWE for successful plaque differentiation; however the results also highlight the importance of choosing optimal imaging settings and using an appropriate wave speed metric when attempting to differentiate different plaque groups.
超声弹性成像是一种有潜力的改善斑块风险分层的方法。然而，对于应该使用什么输出指标或什么样的成像参数才能实现最佳斑块区分，目前还没有明确的共识。出于这个原因，我们开发了一种结合了离体和在体的设置，在此设置中，评估了区分不同刚度的幻影斑块的能力，作为斑块几何形状、推送位置、成像平面和分析波速指标的函数。结果表明，群速度或相速度≥1kHz 显示出区分不同刚度斑块的最高能力，成功分类了分析的 24 种斑块几何形状中的大多数。与横向视图相比，纵向视图中区分斑块的能力也更好。群速度以及相速度<1kHz 显示出对斑块刚度的系统性低估，这源于受限的斑块几何形状，然而，尽管如此，群速度分析显示出对估计斑块刚度的偏差最小（0.1 m/s，相比之下，相速度分析为 0.2 m/s）。SWE 结果也不受 SWE 推送位置的影响，尽管在信噪比（SNR）和产生的斑块粒子速度方面存在明显差异。因此，该研究强调了 SWE 用于成功区分斑块的潜力；然而，结果也强调了在尝试区分不同斑块组时选择最佳成像设置和使用适当的波速指标的重要性。
