Late gadolinium-enhancement cardiac magnetic resonance identifies postinfarction myocardial fibrosis and the border zone at the near cellular level in ex vivo rat heart.
Late gadolinium-enhancement cardiac magnetic resonance identifies postinfarction myocardial fibrosis and the border zone at the near cellular level in ex vivo rat heart.
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DOI：
10.1161/circimaging.108.835793
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发表时间：
2010-11
期刊：
影响因子：
--
通讯作者：
Arai AE
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文献类型：
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作者：
Schelbert EB;Hsu LY;Anderson SA;Mohanty BD;Karim SM;Kellman P;Aletras AH;Arai AE
使用比以前研究高1000倍的分辨率，我们研究了1)晚期Gd增强(LGE)心脏磁共振(CMR)跟踪慢性心肌梗死(MI)纤维化的程度；以及2)不同“平滑”梗死边缘的中间信号强度和部分体积平均与纤维化和存活心肌细胞的杂乱混合物之间的关系。SD大鼠结扎冠状动脉造成心肌梗死。2个月后，静脉注射0.3 mmol/kg Gd后10min处死大鼠。用50×50×50微米体素的三维梯度回波序列在7特斯拉的LGE图像与组织切片(Masson‘s Tichrome)进行比较。纤维化平坦区与LGE区相关性良好(y=1.01x-0.01；r2=0.96p<；0.001)。此外，LGE图像常规检测到2-4个细胞厚的存活心肌细胞的裂隙，这些裂隙分隔纤维组织条带。虽然LGE清楚地检测到以中等信号强度体素为特征的纤维化和存活心肌细胞的无序混合物，但当图像分辨率降低到与显著部分体积平均一致的临床分辨率时，明显的中等信号强度心肌的百分比显著增加(p<；0.01)。这些数据为检测心肌梗死后纤维化在几乎细胞水平上提供了重要的LGE验证。虽然LGE可以检测到不同类型的纤维化斑块和存活的心肌细胞作为中等信号强度的斑块，但中等信号强度体素的百分比与分辨率有关。因此，在临床分辨率下，区分梗死周边区和LGE平均部分体积是具有挑战性的。
Using a resolution 1000 fold higher than prior studies, we studied 1) the degree to which late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) tracks fibrosis from chronic myocardial infarction (MI); and 2) the relationship between intermediate signal intensity and partial volume averaging at distinct “smooth” infarct borders versus disorganized mixtures of fibrosis and viable cardiomyocytes. Sprague Dawley rats underwent MI by coronary ligation. Two months later rats were euthanized 10 minutes after administration of 0.3 mmol/kg intravenous gadolinium. LGE images ex vivo at 7 Tesla with a 3D gradient echo sequence with 50x50x50 micron voxels were compared with histologic sections (Masson’s trichrome). Planimetered histologic and LGE regions of fibrosis correlated well (y = 1.01x – 0.01; R2=0.96; p<0.001). In addition, LGE images routinely detected clefts of viable cardiomyocytes 2–4 cells thick that separated bands of fibrous tissue. While LGE clearly detected disorganized mixtures of fibrosis and viable cardiomyocytes characterized by intermediate signal intensity voxels, the percentage of apparent intermediate signal intensity myocardium increased significantly (p<0.01) when image resolution was degraded to resemble clinical resolution consistent with significant partial volume averaging. These data provide important validation of LGE at nearly the cellular level for detection of fibrosis after MI. While LGE can detect heterogeneous patches of fibrosis and viable cardiomyocytes as patches of intermediate signal intensity, the percentage of intermediate signal intensity voxels is resolution dependent. Thus, at clinical resolutions, distinguishing the peri-infarct border zone from partial volume averaging with LGE is challenging.