严重主动脉瓣狭窄时左心室细胞外重塑的T1映射和特征追踪成像
T1 mapping and feature tracking imaging of left ventricular extracellular remodeling in severe aortic stenosis.
作者信息
Wei Xiaoyu, Jian Xuhua, Xie Jiajun, Chen Rui, Li Xiaodan, Du Zhicheng, Zhong Xiaomei, Li Jinglei, Zhou Xiaobing, Ren Guanmin, Mei Yingjie, Liu Hui
机构信息
School of Medicine, South China University of Technology, Guangzhou, China.
Department of Radiology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.
出版信息
Cardiovasc Diagn Ther. 2020 Dec;10(6):1847-1857. doi: 10.21037/cdt-20-803.
BACKGROUND
Left ventricular (LV) extracellular remodeling is a critical process in aortic stenosis (AS), which is related to functional abnormalities. Data regarding the use of combined T1 mapping and feature tracking (FT) to assess LV extracellular remodeling in severe AS are scarce. This study aimed to investigate the ability of T1-derived and FT-derived parameters to identify and assess the changes in process of LV extracellular remodeling in patients with severe AS.
METHODS
A total of 49 patients with severe AS and 20 healthy volunteers were prospectively recruited. Modified look-locker inversion-recovery T1 mapping and FT imaging were performed in all participants using 3.0-T cardiac magnetic resonance imaging. The degree of myocardial fibrosis was quantified using Masson trichrome stain in biopsy specimens obtained intraoperatively from 13 patients and expressed as collagen volume fraction (CVF). Patients were divided into subgroups according to preserved LV ejection fraction (LVEF) (LVEF ≥50%) or reduced LVEF (LVEF <50%).
RESULTS
Regarding the diffuse fibrosis burden, extracellular volume (ECV) was statistically insignificant between patients with preserved LVEF) and controls (28.0%±3.3% 26.5%±2.3%, P>0.05). ECV in the reduced LVEF group (n=20) was significantly higher than that in the preserved LVEF group (n=29) (30.4%±3.9% 28.0%±3.3%, P<0.05). Regarding the myocardial strain, global longitudinal strain (GLS) showed increasing impairment from the control group to the preserved LVEF AS group to the reduced LVEF AS group (-23.4%±3.3% -18.6%±3.8% -11.2%±4.8%, P<0.05). A significant correlation was found between ECV and CVF (r=0.64, P=0.020), whereas the correlation between GLS and CVF was insignificant. Significant correlations were observed between GLS and LV mass index (r=0.72, P=0.006) and LVEF (r=0.82, P<0.001). However, no correlations were found between ECV and LV mass index (P=0.172) and between ECV and LVEF (P=0.339). Discrimination of patients with preserved LVEF from controls, GLS yielded the best diagnostic performance as defined by the area of under the curve (-0.83), and GLS, ECV, and post-T1 were significant discriminators after regression analysis.
CONCLUSIONS
In the process of LV extracellular remodeling in severe AS, ECV is the structural marker of extracellular fibrosis burden, and GLS is the functional marker before the fibrosis burden intensifies.
背景
左心室（LV）细胞外重塑是主动脉瓣狭窄（AS）的一个关键过程，与功能异常相关。关于联合使用T1映射和特征追踪（FT）来评估重度AS患者左心室细胞外重塑的数据很少。本研究旨在探讨T1衍生参数和FT衍生参数识别和评估重度AS患者左心室细胞外重塑过程中变化的能力。
方法
前瞻性招募了49例重度AS患者和20名健康志愿者。所有参与者均使用3.0-T心脏磁共振成像进行改良的锁相环反转恢复T1映射和FT成像。使用Masson三色染色对术中从13例患者获取的活检标本中的心肌纤维化程度进行量化，并表示为胶原体积分数（CVF）。根据左心室射血分数（LVEF）保留（LVEF≥50%）或降低（LVEF<50%）将患者分为亚组。
结果
关于弥漫性纤维化负担，LVEF保留的患者与对照组之间的细胞外容积（ECV）在统计学上无显著差异（28.0%±3.3%对26.5%±2.3%，P>0.05）。LVEF降低组（n=20）的ECV显著高于LVEF保留组（n=29）（30.4%±3.9%对28.0%±3.3%，P<0.05）。关于心肌应变，整体纵向应变（GLS）从对照组到LVEF保留的AS组再到LVEF降低的AS组显示出逐渐加重的损害（-23.4%±3.3%对-18.6%±3.8%对-11.2%±4.8%，P<0.05）。发现ECV与CVF之间存在显著相关性（r=0.64，P=0.020），而GLS与CVF之间的相关性不显著。观察到GLS与左心室质量指数（r=0.72，P=0.006）和LVEF（r=0.82，P<0.001）之间存在显著相关性。然而，未发现ECV与左心室质量指数之间（P=0.172）以及ECV与LVEF之间（P=0.339）存在相关性。将LVEF保留的患者与对照组区分开来，GLS产生了曲线下面积定义的最佳诊断性能（-0.83），并且在回归分析后，GLS、ECV和T1后值是显著的鉴别指标。
结论
在重度AS患者左心室细胞外重塑过程中，ECV是细胞外纤维化负担的结构标志物，而GLS是纤维化负担加剧前的功能标志物。
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