Baldewsing Radjkumarsing A, Danilouchkine Mikhail G, Mastik Frits, Schaar Johannes A, Serruys Patrick W, van der Steen Antonius F W
Department of Biomedical Engineering, Erasmus Medical Center, Rotterdam, The Netherlands.
IEEE Trans Inf Technol Biomed. 2008 May;12(3):277-89. doi: 10.1109/titb.2007.907980.
The rupture of thin-cap fibroatheroma (TCFA) plaques is a major cause of acute coronary events. A TCFA has a trombogenic soft lipid core, shielded from the blood stream by a thin, possibly inflamed, stiff cap. The majority of atherosclerotic plaques resemble a TCFA in terms of overall structural composition, but have a more complex, heterogeneous morphology. An assessment of the material distribution is vital for quantifying the plaque's mechanical stability and for determining the effect of plaque-stabilizing pharmaceutical agents. We describe a new automated inverse elasticity method, intravascular ultrasound (IVUS) modulography, which is capable of reconstructing a heterogeneous Young's modulus distribution. The elastogram (i.e., spatial strain distribution) of the plaque is the input for the method, and is measured using the clinically available technique, IVUS elastography. Our method incorporates a novel divide-and-conquer strategy, allowing the reconstruction of TCFAs as well as heterogeneous plaques with localized regions of soft, weakened tissue. The method was applied to ex vivo elastograms, which were simulated from the cross sections of postmortem human coronary plaques. To demonstrate the clinical feasibility of the method, measured elastograms from human atherosclerotic coronary arteries were analyzed. One elastogram was measured in vitro; the other, in vivo. The method approximated the true Young's modulus distribution of all simulated plaques, while the in vitro reconstruction was in agreement with histology. In conclusion, the IVUS modulography in combination with the IVUS elastography has strong potential to become an all-encompassing modality for detecting plaques, for assessing the information related to their rupture-proneness, and for imaging their heterogeneous elastic material composition.
薄帽纤维粥样硬化（TCFA）斑块破裂是急性冠脉事件的主要原因。TCFA有一个易形成血栓的软脂质核心，被一层薄的、可能发炎的硬帽与血流隔开。大多数动脉粥样硬化斑块在整体结构组成上类似于TCFA，但具有更复杂、异质性的形态。对物质分布的评估对于量化斑块的机械稳定性以及确定斑块稳定药物的效果至关重要。我们描述了一种新的自动逆弹性方法——血管内超声（IVUS）调制成像，它能够重建异质性的杨氏模量分布。斑块的弹性图（即空间应变分布）是该方法的输入，通过临床可用技术IVUS弹性成像进行测量。我们的方法采用了一种新颖的分治策略，能够重建TCFA以及具有局部软质、弱化组织区域的异质性斑块。该方法应用于从人冠状动脉死后斑块横截面模拟得到的离体弹性图。为了证明该方法的临床可行性，对来自人动脉粥样硬化冠状动脉的实测弹性图进行了分析。一幅弹性图是在体外测量的；另一幅是在体内测量的。该方法近似于所有模拟斑块的真实杨氏模量分布，而体外重建结果与组织学结果一致。总之，IVUS调制成像与IVUS弹性成像相结合有很大潜力成为一种全面的模式，用于检测斑块、评估与它们破裂倾向相关的信息以及对其异质性弹性物质组成进行成像。
