Baldewsing Radj A, de Korte Chris L, Schaar Johannes A, Mastik Frits, van der Steen Antonius F W
Biomedical Engineering, Thoraxcenter, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands.
Ultrasound Med Biol. 2004 Jun;30(6):803-13. doi: 10.1016/j.ultrasmedbio.2004.04.005.
Intravascular ultrasound (US) elastography measures in an artery the arterial radial strain and displays it in an elastogram. An elastogram adds diagnostic information, such as the proneness of a plaque to rupture and its material composition. However, radial strain depends upon the material properties of an artery, including geometry and used catheter position. Therefore, there is not always a one-to-one correspondence between radial strain and rupture-proneness or material composition. Both the dependence and the correspondence can be quantified after a proper finite element model (FEM) is available. Therefore, this paper proposes a FEM and shows that it can model the arterial strain behavior. Its modelling capability was evaluated by comparing simulated with measured elastograms. Measured elastograms were processed from radiofrequency (RF) data obtained in vitro from six objects: a vessel-mimicking phantom and five excised human atherosclerotic coronary arteries. A FEM was created for each object and used to simulate an elastogram; the material properties and geometry of the FEM were obtained from the histology of the object. Comparison was performed upon high strain regions (HStR), because these regions have proven to contain plaques that show the hallmarks of vulnerable plaques. Eight HStR were automatically identified from the five arteries. Statistical tests showed that there was no significant difference between simulated and corresponding measured elastograms in location, surface area or mean strain value of a HStR. The results demonstrate that the FEM can simulate elastograms measured from arteries. As such, the FEM may help in quantifying strain-dependencies and assist in tissue characterization by reconstructing a Young's modulus image from a measured elastogram.
血管内超声（US）弹性成像可测量动脉中的动脉径向应变，并将其显示在弹性图中。弹性图可提供诊断信息，例如斑块破裂的倾向及其材料成分。然而，径向应变取决于动脉的材料特性，包括几何形状和所用导管的位置。因此，径向应变与破裂倾向或材料成分之间并不总是一一对应的关系。在获得合适的有限元模型（FEM）后，这种依赖性和对应关系都可以进行量化。因此，本文提出了一种有限元模型，并表明它可以模拟动脉应变行为。通过将模拟弹性图与实测弹性图进行比较，对其建模能力进行了评估。实测弹性图是根据从六个物体体外获得的射频（RF）数据处理而成的：一个血管模拟体模和五条切除的人类动脉粥样硬化冠状动脉。为每个物体创建了一个有限元模型，并用于模拟弹性图；有限元模型的材料特性和几何形状是从物体的组织学中获得的。对高应变区域（HStR）进行了比较，因为这些区域已被证明含有显示易损斑块特征的斑块。从五条动脉中自动识别出八个高应变区域。统计测试表明，在高应变区域的位置、表面积或平均应变值方面，模拟弹性图与相应的实测弹性图之间没有显著差异。结果表明，有限元模型可以模拟从动脉测得的弹性图。因此，有限元模型可能有助于量化应变依赖性，并通过从实测弹性图重建杨氏模量图像来辅助组织表征。
