Fiber architecture in remodeled myocardium revealed with a quantitative diffusion CMR tractography framework and histological validation.
Fiber architecture in remodeled myocardium revealed with a quantitative diffusion CMR tractography framework and histological validation.
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DOI：
10.1186/1532-429x-14-70
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发表时间：
2012-10-12
期刊：
影响因子：
--
通讯作者：
Sosnovik DE
中科院分区：
文献类型：
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作者：
Mekkaoui C;Huang S;Chen HH;Dai G;Reese TG;Kostis WJ;Thiagalingam A;Maurovich-Horvat P;Ruskin JN;Hoffmann U;Jackowski MP;Sosnovik DE
心肌梗死后远区肌纤维重组的二维研究。然而，只有将肌纤维视为连续的三维实体，才能充分理解重建心脏的微观结构重组。因此，本研究的目的是开发一种定量3D弥散CMR心脏束状图技术，并应用该方法定量重建心脏远端区域的纤维结构。对正常人、羊、大鼠及梗死羊心脏进行体外弥散张量CMR。采用四阶龙格-库塔积分技术生成纤维束，并根据纤维束的中位数、平均值、最大值或最小螺旋角（HA）进行统计分类。从这些HA统计数据之间的关系中得出了一个通道一致性指数。采用相衬显微镜进行组织学验证。在正常心脏中，心内膜下和心外膜下肌纤维分别呈阳性和阴性，在心肌中部周围形成对称分布。然而，在梗死心脏的远区，观察到血凝素的显著正转移。HA阳性与阴性之比由正常心脏（0.96±0.16）降至重构心脏远区（0.22±0.08）（p<0.05）。形态学上证实了这一点，重构心脏远端区心膜下HA从正常心脏的- 52.03°±2.94°降至- 37.48°±4.05°（p < 0.05）。在重建心脏的远端区域观察到三维纤维连续体的显著重组。远区血凝素正向（向右）移位在心膜下最大，但涉及心肌的所有层。基于束状图的量化，首次在重建的心脏中进行，可能为评估梗死后左心室的局部变化提供一个框架。
The study of myofiber reorganization in the remote zone after myocardial infarction has been performed in 2D. Microstructural reorganization in remodeled hearts, however, can only be fully appreciated by considering myofibers as continuous 3D entities. The aim of this study was therefore to develop a technique for quantitative 3D diffusion CMR tractography of the heart, and to apply this method to quantify fiber architecture in the remote zone of remodeled hearts. Diffusion Tensor CMR of normal human, sheep, and rat hearts, as well as infarcted sheep hearts was performed ex vivo. Fiber tracts were generated with a fourth-order Runge-Kutta integration technique and classified statistically by the median, mean, maximum, or minimum helix angle (HA) along the tract. An index of tract coherence was derived from the relationship between these HA statistics. Histological validation was performed using phase-contrast microscopy. In normal hearts, the subendocardial and subepicardial myofibers had a positive and negative HA, respectively, forming a symmetric distribution around the midmyocardium. However, in the remote zone of the infarcted hearts, a significant positive shift in HA was observed. The ratio between negative and positive HA variance was reduced from 0.96 ± 0.16 in normal hearts to 0.22 ± 0.08 in the remote zone of the remodeled hearts (p<0.05). This was confirmed histologically by the reduction of HA in the subepicardium from −52.03° ± 2.94° in normal hearts to −37.48° ± 4.05° in the remote zone of the remodeled hearts (p < 0.05). A significant reorganization of the 3D fiber continuum is observed in the remote zone of remodeled hearts. The positive (rightward) shift in HA in the remote zone is greatest in the subepicardium, but involves all layers of the myocardium. Tractography-based quantification, performed here for the first time in remodeled hearts, may provide a framework for assessing regional changes in the left ventricle following infarction.