Guo Xiaoya, Giddens Don P, Molony David, Yang Chun, Samady Habib, Zheng Jie, Mintz Gary S, Maehara Akiko, Wang Liang, Pei Xuan, Li Zhi-Yong, Tang Dalin
Department of Mathematics, Southeast University, Nanjing 210096, China.
Department of Medicine, Emory University School of Medicine, Atlanta, GA 30307.
J Biomech Eng. 2018 Apr 1;140(4):0410051-04100512. doi: 10.1115/1.4038263.
Accurate cap thickness and stress/strain quantifications are of fundamental importance for vulnerable plaque research. Virtual histology intravascular ultrasound (VH-IVUS) sets cap thickness to zero when cap is under resolution limit and IVUS does not see it. An innovative modeling approach combining IVUS and optical coherence tomography (OCT) is introduced for cap thickness quantification and more accurate cap stress/strain calculations. In vivo IVUS and OCT coronary plaque data were acquired with informed consent obtained. IVUS and OCT images were merged to form the IVUS + OCT data set, with biplane angiography providing three-dimensional (3D) vessel curvature. For components where VH-IVUS set zero cap thickness (i.e., no cap), a cap was added with minimum cap thickness set as 50 and 180 μm to generate IVUS50 and IVUS180 data sets for model construction, respectively. 3D fluid-structure interaction (FSI) models based on IVUS + OCT, IVUS50, and IVUS180 data sets were constructed to investigate cap thickness impact on stress/strain calculations. Compared to IVUS + OCT, IVUS50 underestimated mean cap thickness (27 slices) by 34.5%, overestimated mean cap stress by 45.8%, (96.4 versus 66.1 kPa). IVUS50 maximum cap stress was 59.2% higher than that from IVUS + OCT model (564.2 versus 354.5 kPa). Differences between IVUS and IVUS + OCT models for cap strain and flow shear stress (FSS) were modest (cap strain <12%; FSS <6%). IVUS + OCT data and models could provide more accurate cap thickness and stress/strain calculations which will serve as basis for further plaque investigations.
准确的帽厚度以及应力/应变量化对于易损斑块研究至关重要。当帽厚度低于分辨率极限且血管内超声（IVUS）无法检测到时，虚拟组织学血管内超声（VH-IVUS）会将帽厚度设为零。本文介绍了一种结合IVUS和光学相干断层扫描（OCT）的创新建模方法，用于帽厚度量化以及更准确的帽应力/应变计算。在获得知情同意后采集了体内IVUS和OCT冠状动脉斑块数据。将IVUS和OCT图像合并以形成IVUS + OCT数据集，双平面血管造影提供三维（3D）血管曲率。对于VH-IVUS将帽厚度设为零的部分（即无帽），添加帽，将最小帽厚度分别设为50和180μm，以生成用于模型构建的IVUS50和IVUS180数据集。基于IVUS + OCT、IVUS50和IVUS180数据集构建3D流固耦合（FSI）模型，以研究帽厚度对应力/应变计算的影响。与IVUS + OCT相比，IVUS50低估平均帽厚度（27个切片）34.5%，高估平均帽应力45.8%（分别为96.4与66.1 kPa）。IVUS50的最大帽应力比IVUS + OCT模型高59.2%（分别为564.2与354.5 kPa）。IVUS与IVUS + OCT模型在帽应变和血流剪应力（FSS）方面的差异较小（帽应变<12%；FSS<6%）。IVUS + OCT数据和模型能够提供更准确的帽厚度以及应力/应变计算，这将为进一步的斑块研究奠定基础。
