Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States.
Department of Radiology, Harvard Medical School, Boston, United States.
Elife. 2022 Apr 29;11:e71186. doi: 10.7554/eLife.71186.
The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic arteries (diameter 50-300 µm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight magnetic resonance angiography (TOF-MRA)-which is well suited to high 3D imaging resolutions-has not been applied to imaging the pial arteries. Here, we provide a theoretical framework that outlines how TOF-MRA can visualize small pial arteries in vivo, by employing extremely small voxels at the size of individual vessels. We then provide evidence for this theory by imaging the pial arteries at 140 µm isotropic resolution using a 7 Tesla (T) magnetic resonance imaging (MRI) scanner and prospective motion correction, and show that pial arteries one voxel width in diameter can be detected. We conclude that imaging pial arteries is not limited by slow blood flow, but instead by achievable image resolution. This study represents the first targeted, comprehensive account of imaging pial arteries in vivo in the human brain. This ultra-high-resolution angiography will enable the characterization of pial vascular anatomy across the brain to investigate patterns of blood supply and relationships between vascular and functional architecture.
人脑的脑膜动脉血管是新皮质的唯一血液供应，但这些中观动脉（直径 50-300μm）的形态和拓扑结构的定量数据仍然很少。由于通常假设这些血管中的血流速度非常缓慢，因此不适合进行非侵入性的时间飞跃磁共振血管造影术（TOF-MRA）-这种技术非常适合高 3D 成像分辨率-尚未应用于脑膜动脉成像。在这里，我们提供了一个理论框架，概述了如何通过使用单个血管大小的极小体素来可视化体内的小脑膜动脉。然后，我们通过在 7 特斯拉（T）磁共振成像（MRI）扫描仪上使用 140μm 各向同性分辨率和前瞻性运动校正来对脑膜动脉进行成像，并提供了这一理论的证据，表明可以检测到直径为一个体素宽度的脑膜动脉。我们的结论是，脑膜动脉的成像不受血流缓慢的限制，而是受可实现的图像分辨率的限制。这项研究代表了首次在人类大脑中针对脑膜动脉进行体内成像的全面综合描述。这种超高分辨率血管造影术将能够描述整个大脑的脑膜血管解剖结构，以研究血液供应模式和血管与功能结构之间的关系。
