Leung K Y Esther, Baldewsing Radjkumarsing A, Mastik Frits, Schaar Johannes Antonius, Gisolf Andries, van der Steen Antonius F W
Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
IEEE Trans Ultrason Ferroelectr Freq Control. 2006 Jul;53(7):1269-80. doi: 10.1109/tuffc.2006.1665075.
Rupture of vulnerable plaques in coronary arteries is the major cause of acute coronary syndromes. Most vulnerable plaques consist of a thin fibrous cap covering an atheromous core. These plaques can be identified using intravascular ultrasound (IVUS) palpography, which measures radial strain by cross-correlating RF signals at different intraluminal pressures. Multiple strain images (i.e., partial palpograms) are averaged per heart cycle to produce a more robust compounded palpogram. However, catheter motion due to cardiac activity causes misalignment of the RF signals and thus of the partial palpograms, resulting in less valid strain estimates. To compensate for in-plane catheter rotation and translation, we devised four methods based on block matching. The global rotation block matching (GRBM) and contour mapping (CMAP) methods measure catheter rotation, and local block matching (LBM) and catheter rotation and translation (CRT) estimate displacements of local tissue regions. These methods were applied to nine in vivo pullback acquisitions, made with a 20 MHz phased-array transducer. We found that all these methods significantly increase the number of valid strain estimates in the partial and compounded palpograms (P < 0.008). The best method, LBM, attained an average increase of 17% and 15%, respectively. Implementation of this method should improve the information coming from IVUS palpography, leading to better vulnerable plaque detection.
冠状动脉易损斑块破裂是急性冠状动脉综合征的主要原因。大多数易损斑块由覆盖粥样核心的薄纤维帽组成。这些斑块可以使用血管内超声（IVUS）触诊法来识别，该方法通过在不同腔内压力下对射频信号进行互相关来测量径向应变。每个心动周期对多个应变图像（即部分触诊图）进行平均，以生成更可靠的复合触诊图。然而，由于心脏活动引起的导管运动导致射频信号以及部分触诊图的错位，从而导致应变估计的有效性降低。为了补偿平面内导管的旋转和平移，我们设计了四种基于块匹配的方法。全局旋转块匹配（GRBM）和轮廓映射（CMAP）方法测量导管旋转，局部块匹配（LBM）以及导管旋转和平移（CRT）估计局部组织区域的位移。这些方法应用于使用20 MHz相控阵换能器进行的九次体内回撤采集。我们发现所有这些方法都显著增加了部分和复合触诊图中有效应变估计的数量（P < 0.008）。最佳方法LBM分别平均增加了17%和15%。实施该方法应能改善来自IVUS触诊法的信息，从而更好地检测易损斑块。
