Cerebral Microcirculation Unit, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive MSC 1065, Building 10 Room B1D106, Bethesda, MD, 20892-1065, USA.
Transl Stroke Res. 2012 Mar;3(1):44-55. doi: 10.1007/s12975-011-0115-z. Epub 2011 Nov 16.
Collateral circulation, defined as the supplementary vascular network that maintains cerebral blood flow (CBF) when the main vessels fail, constitutes one important defense mechanism of the brain against ischemic stroke. In the present study, continuous arterial spin labeling (CASL) was used to quantify CBF and obtain perfusion territory maps of the major cerebral arteries in spontaneously hypertensive rats (SHRs) and their normotensive Wistar-Kyoto (WKY) controls. Results show that both WKY and SHR have complementary, yet significantly asymmetric perfusion territories. Right or left dominances were observed in territories of the anterior (ACA), middle and posterior cerebral arteries, and the thalamic artery. Magnetic resonance angiography showed that some of the asymmetries were correlated with variations of the ACA. The leptomeningeal circulation perfusing the outer layers of the cortex was observed as well. Significant and permanent changes in perfusion territories were obtained after temporary occlusion of the right middle cerebral artery in both SHR and WKY, regardless of their particular dominance. However, animals with right dominance presented a larger volume change of the left perfusion territory (23 ± 9%) than animals with left dominance (7 ± 5%, P < 0.002). The data suggest that animals with contralesional dominance primarily safeguard local CBF values with small changes in contralesional perfusion territory, while animals with ipsilesional dominance show a reversal of dominance and a substantial increase in contralesional perfusion territory. These findings show the usefulness of CASL to probe the collateral circulation.
侧支循环是指当主要血管发生故障时维持脑血流（CBF）的补充血管网络，是大脑对缺血性中风的重要防御机制之一。在本研究中，连续动脉自旋标记（CASL）用于定量 CBF，并获得自发性高血压大鼠（SHR）及其正常血压的 Wistar-Kyoto（WKY）对照的主要大脑动脉的灌注区域图。结果表明，WKY 和 SHR 均具有互补但明显不对称的灌注区域。在前（ACA）、中脑和后大脑动脉以及丘脑动脉的区域观察到右或左优势。磁共振血管造影显示，一些不对称性与 ACA 的变化有关。也观察到了脑膜循环，为皮层外层提供血液。在 SHR 和 WKY 中，无论其特定优势如何，临时阻断右侧大脑中动脉后均获得了灌注区域的显著和永久性变化。然而，右优势动物的左灌注区域的体积变化（23±9%）大于左优势动物（7±5%，P<0.002）。这些数据表明，对侧优势动物主要通过对侧灌注区域的小变化来保护局部 CBF 值，而同侧优势动物则会出现优势反转和对侧灌注区域的显著增加。这些发现表明 CASL 可用于探测侧支循环。
