Qiao Huiyu, Li Dongye, Cao Jingli, Qi Haikun, Han Yongjun, Han Hualu, Xu Huimin, Wang Tao, Chen Shuo, Chen Huijun, Wang Yajie, Zhao Xihai
Center for Biomedical Imaging Research, Department of Biomedical Engineering, Tsinghua University School of Medicine, Haidian District, Beijing, 100084, China.
Department of Radiology, Sun Yat-sen Memorial hospital, Sun Yat-sen University, Guangzhou, China.
J Cardiovasc Magn Reson. 2020 May 21;22(1):38. doi: 10.1186/s12968-020-00624-0.
It has been proved that multi-contrast cardiovascular magnetic resonance (CMR) vessel wall imaging could be used to characterize carotid vulnerable plaque components according to the signal intensity on different contrast images. The signal intensity of plaque components is mainly dependent on the values of T1 and T2 relaxation. T1 mapping recently showed a potential in identifying plaque components but it is not well validated by histology. This study aimed to validate the usefulness of in vivo T1 mapping in assessing carotid vulnerable plaque components by histology.
Thirty-four subjects (mean age, 64.0 ± 8.9 years; 26 males) with carotid plaques referred to carotid endarterectomy were prospectively enrolled and underwent 3 T CMR imaging from May 2017 to October 2017. The T1 values of intraplaque hemorrhage (IPH), necrotic core (NC) and loose matrix (LM) which were identified on multi-contrast vessel wall images or histology were measured on in-vivo T1 mapping. The IPHs were divided into two types based on the proportion of the area of fresh hemorrhage on histology. The T1 values of different plaque components were compared using Mann-Whitney U test and the agreement between T1 mapping and histology in identifying and quantifying IPH was analyzed with Cohen's Kappa and intraclass correlation coefficient (ICC).
Of 34 subjects, 19 had histological specimens matched with CMR imaging. The mean T1 values of IPH (651 ± 253 ms), NC (1161 ± 182 ms) and LM (1447 ± 310 ms) identified by histology were significantly different. The T1 values of Type 1 IPH were significantly shorter than that of Type 2 IPH (456 ± 193 ms vs. 775 ± 205 ms, p < 0.001). Moderate to excellent agreement was found in identification (kappa = 0.51, p < 0.001), classification (kappa = 0.40, p = 0.028) and segmentation (ICC = 0.816, 95% CI 0.679-0.894) of IPHs between T1 mapping and histology.
The T1 values of carotid plaque components, particularly for intraplaque hemorrhage, are differentiable, and the stage of intraplaque hemorrhage can be classified according to T1 values, suggesting the potential capability of assessment of vulnerable plaque components by T1 mapping.
已证实多对比心血管磁共振（CMR）血管壁成像可根据不同对比图像上的信号强度来表征颈动脉易损斑块成分。斑块成分的信号强度主要取决于T1和T2弛豫值。T1映射最近显示出在识别斑块成分方面的潜力，但尚未得到组织学的充分验证。本研究旨在通过组织学验证体内T1映射在评估颈动脉易损斑块成分方面的有用性。
前瞻性纳入34例接受颈动脉内膜切除术的颈动脉斑块患者（平均年龄64.0±8.9岁；26例男性），于2017年5月至2017年10月接受3T CMR成像。在多对比血管壁图像或组织学上识别出的斑块内出血（IPH）、坏死核心（NC）和疏松基质（LM）的T1值在体内T1映射上进行测量。根据组织学上新鲜出血面积的比例将IPH分为两种类型。使用Mann-Whitney U检验比较不同斑块成分的T1值，并使用Cohen's Kappa和组内相关系数（ICC）分析T1映射与组织学在识别和量化IPH方面的一致性。
34例受试者中，19例有与CMR成像匹配的组织学标本。组织学识别出的IPH（651±253ms）、NC（1161±182ms）和LM（1447±310ms）的平均T1值有显著差异。1型IPH的T1值明显短于2型IPH（456±193ms对775±205ms，p<0.001）。在T1映射与组织学之间，IPH的识别（kappa=0.51，p<0.001）、分类（kappa=0.40，p=0.028）和分割（ICC=0.816，95%CI 0.679-0.894）方面发现了中度至高度一致性。
颈动脉斑块成分的T1值，特别是斑块内出血的T1值是可区分的，并且可以根据T1值对斑块内出血的阶段进行分类，这表明T1映射在评估易损斑块成分方面具有潜在能力。
