Visualizing the cardiac conduction network using MR microscopy and diffusion

描述(申请人提供)：心脏负责将氧气和营养物质输送到身体的所有组织，并通过肌肉细胞的协调收缩来执行这一功能。当这些收缩发生协调时，心脏就会纤颤， 或者停止跳动。负责这种协调的特殊细胞系统是心脏传导网络，通常被称为浦肯野网络。这些专门的肌肉细胞迅速传递收缩信号，因此心脏底部的心脏组织几乎与心脏顶端的组织同时收缩。虽然我们知道这些特化细胞已经有一百多年了，但目前我们能够看到它们的唯一方法是取出心脏，并在光学显微镜下检查它的碎片。这些目前的技术是劳动密集型的，并且会导致组织的破坏。我们已经开发了一种非侵入性的方法，利用磁共振显微镜和扩散成像来确定这些特殊细胞的解剖位置。使用佛罗里达州盖恩斯维尔国家高场磁实验室的磁体，我们获得了迄今为止最高分辨率的心肌组织磁共振图像(7um各向同性分辨率)，并在分辨率低至40um的情况下进行了扩散成像。我们可以看到房室结、传导束、左、右束支，以及随后从室间隔延伸到室腔的纤维(如自由流动的浦肯野纤维)。我们建议进一步提高我们从心肌细胞中区分这些纤维的能力，并构建传导网络的图谱，以帮助未来的建模。我们还将比较这一网络在男性和女性年轻人中的解剖，因为在这个年龄段，心脏性猝死的发生率在性别之间有很大的不同。

DESCRIPTION (provided by applicant): The heart is responsible for transporting oxygen and nutrients to all tissues in the body, and it performs this function through the coordinated contraction of muscle cells. When coordination of these contractions occurs, the heart fibrillates, or stops beating. The systems of specialized cells that are responsible for this coordination are the cardiac conducting network, commonly referred to as the Purkinje network. These specialized muscle cells rapidly conduct signals to contract, so that the heart tissue at the base of the heart contracts at nearly the same time as tissue at the apex of the heart. Although we have known about these specialized cells for over a hundred years, the only way we are currently able to see them is if we remove the heart, and examine pieces of it under light microscopy. These current techniques are labor intensive, and result in destruction of tissue. We have developed a non-invasive means to determine the anatomical location of these specialized cells using magnetic resonance microscopy and diffusion imaging. Using magnets at the National High Field Magnet Laboratory in Gainesville, Florida, we have obtained the highest resolution MR images to date of myocardial tissue (7um isotropic resolution), and performed diffusion imaging at resolutions down to 40um. We are able to visualize the atrial-ventricular node, conducting bundle, left and right bundle branches, and subsequent fibers that extend down the ventricular septum of the heart and into the ventricular cavities (as free-running Purkinje fibers). We propose to further improve our ability to discriminate these fibers from cardiac muscle cells, and to construct atlases of the conduction network to aid in future modeling. We will also compare the anatomy of this network in both male and female young adults, since the incidence of sudden cardiac death is dramatically different between the genders at this age.