Glasgow Experimental MRI Centre (GEMRIC), Division of Clinical Neuroscience, Garscube Estate, University of Glasgow, Glasgow, Scotland.
Stroke. 2009 Dec;40(12):3864-8. doi: 10.1161/STROKEAHA.109.559021. Epub 2009 Sep 24.
Stroke-prone spontaneously hypertensive rats (SHRSP) are a highly pertinent stroke model with increased sensitivity to focal ischemia compared with the normotensive reference strain (Wistar-Kyoto rats; WKY). Study aims were to investigate temporal changes in the ischemic penumbra in SHRSP compared with WKY.
Permanent middle cerebral artery occlusion was induced with an intraluminal filament. Diffusion- (DWI) and perfusion- (PWI) weighted magnetic resonance imaging was performed from 1 to 6 hours after stroke, with the PWI-DWI mismatch used to define the penumbra and thresholded apparent diffusion coefficient (ADC) maps used to define ischemic damage.
There was significantly more ischemic damage in SHRSP than in WKY from 1 to 6 hours after stroke. The perfusion deficit remained unchanged in WKY (39.9+/-6 mm(2) at 1 hour, 39.6+/-5.3 mm(2) at 6 hours) but surprisingly increased in SHRSP (43.9+/-9.2 mm(2) at 1 hour, 48.5+/-7.4 mm(2) at 6 hours; P=0.01). One hour after stroke, SHRSP had a significantly smaller penumbra (3.4+/-5.8 mm(2)) than did WKY (9.7+/-3.8, P=0.03). In WKY, 56% of the 1-hour penumbra area was incorporated into the ADC lesion by 6 hours, whereas in SHRSP, the small penumbra remained static owing to the temporal increase in both ADC lesion size and perfusion deficit.
First, SHRSP have significantly more ischemic damage and a smaller penumbra than do WKY within 1 hour of stroke; second, the penumbra is recruited into the ADC abnormality over time in both strains; and third, the expanding perfusion deficit in SHRSP predicts more tissue at risk of infarction. These results have important implications for management of stroke patients with preexisting hypertension and suggest ischemic damage could progress at a faster rate and over a longer time frame in the presence of hypertension.
易发生中风的自发性高血压大鼠（SHRSP）是一种与正常血压参考株（Wistar-Kyoto 大鼠；WKY）相比，对局灶性缺血更为敏感的高度相关中风模型。本研究旨在比较 SHRSP 与 WKY 之间在中风后缺血半影区的时间变化。
采用管内线栓法诱导永久性大脑中动脉闭塞。在中风后 1 至 6 小时进行弥散加权（DWI）和灌注加权（PWI）磁共振成像，使用 PWI-DWI 不匹配来定义半影区，用表观扩散系数（ADC）阈值图来定义缺血性损伤。
中风后 1 至 6 小时，SHRSP 的缺血性损伤明显多于 WKY。WKY 的灌注缺损保持不变（1 小时时为 39.9+/-6 mm(2)，6 小时时为 39.6+/-5.3 mm(2)），但 SHRSP 的灌注缺损却出人意料地增加（1 小时时为 43.9+/-9.2 mm(2)，6 小时时为 48.5+/-7.4 mm(2)；P=0.01）。中风后 1 小时，SHRSP 的半影区明显小于 WKY（3.4+/-5.8 mm(2)比 9.7+/-3.8，P=0.03）。在 WKY 中，1 小时的半影区有 56%在 6 小时时被 ADC 病变所包含，而在 SHRSP 中，由于 ADC 病变和灌注缺损的时间增加，较小的半影区保持不变。
首先，与 WKY 相比，SHRSP 在中风后 1 小时内的缺血性损伤和较小的半影区显著增加；其次，在两种株系中，半影区随着时间的推移逐渐被 ADC 异常所包含；第三，SHRSP 不断扩大的灌注缺损预示着更多的组织有梗死的风险。这些结果对患有高血压的中风患者的管理具有重要意义，表明在存在高血压的情况下，缺血性损伤可能以更快的速度和更长的时间框架进展。
