Department of Biomedical Engineering, University of Arizona College of Engineering, Tucson, Arizona, USA.
Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona, USA.
J Neuroimaging. 2023 Jul-Aug;33(4):534-546. doi: 10.1111/jon.13115. Epub 2023 May 14.
Cerebrovascular dynamics and pathomechanisms that evolve in the minutes and hours following traumatic vascular injury in the brain remain largely unknown. We investigated the pathophysiology evolution in mice within the first 3 hours after closed-head traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH), two significant traumatic vascular injuries.
We took a multimodal imaging approach using photoacoustic imaging, color Doppler ultrasound, and MRI to track injury outcomes using a variety of metrics.
Brain oxygenation and velocity-weighted volume of blood flow (VVF) values significantly decreased from baseline to 15 minutes after both TBI and SAH. TBI resulted in 19.2% and 41.0% ipsilateral oxygenation and VVF reductions 15 minutes postinjury, while SAH resulted in 43.9% and 85.0% ipsilateral oxygenation and VVF reduction (p < .001). We found partial recovery of oxygenation from 15 minutes to 3 hours after injury for TBI but not SAH. Hemorrhage, edema, reduced perfusion, and altered diffusivity were evident from MRI scans acquired 90-150 minutes after injury in both injury models, although the spatial distribution was mostly focal for TBI and diffuse for SAH.
The results reveal that the cerebral oxygenation deficits immediately following injuries are reversible for TBI and irreversible for SAH. Our findings can inform future studies on mitigating these early responses to improve long-term recovery.
颅脑创伤后数分钟至数小时内的脑血管动力学和病理机制仍知之甚少。我们研究了闭合性颅脑创伤（TBI）和蛛网膜下腔出血（SAH）后 3 小时内小鼠的病理生理学演变，这两种创伤性血管损伤都很重要。
我们采用多模态成像方法，使用光声成像、彩色多普勒超声和 MRI 来跟踪使用各种指标的损伤结果。
TBI 和 SAH 后，脑氧合和血流速度加权体积（VVF）值从基线显著降低至 15 分钟。TBI 导致伤后 15 分钟同侧氧合和 VVF 分别减少 19.2%和 41.0%，而 SAH 导致同侧氧合和 VVF 分别减少 43.9%和 85.0%（p<.001）。我们发现 TBI 伤后 15 分钟至 3 小时的氧合部分恢复，但 SAH 则没有。两种损伤模型在伤后 90-150 分钟的 MRI 扫描中均可见出血、水肿、灌注减少和弥散改变，但 TBI 的空间分布主要为局灶性，而 SAH 则为弥漫性。
研究结果表明，TBI 损伤后立即出现的脑氧合不足是可逆的，而 SAH 则是不可逆的。我们的发现可以为未来减轻这些早期反应以改善长期恢复的研究提供信息。
