创伤性脑损伤后动态CT灌注像的实验研究

Experimental study on hemodynamics of traumatic brain injury using dynamic CT perfusion image

目的采用64排螺旋CT对创伤性脑损伤大鼠进行动态灌注扫描,以了解脑损伤后局部脑灌注改变。方法45只成熟雄性SD大鼠分为3组:正常对照组、假手术组和实验组。3组均于大鼠脑损伤模型建立后1h、6h、24h、3d、7d、14d、21d分别行头颅CT灌注像(CT perfusion,CTP)扫描。选取伤侧损伤灶周围2mm内及健侧镜像区为观察兴趣区。CTP后取脑做脑损伤区域石蜡固定切片,在光镜下观察大脑皮层损伤区的病理改变。结果创伤后1 h损伤局部就有明显的脑血流量(cerebral blood flow,CBF)和脑血容量(cerebral blood volume,CBV)降低。伤后24h CBF、CBV开始增高,伤后3 d时达到高峰;伤后14d二者基本恢复正常。呈现损伤灶局部早期低灌注(1h左右),随后呈现高灌注(6h至7d),晚期脑灌注倾于正常的动态脑血液动力学变化。健侧CBF在伤侧CBF伤后3d明显增高时则呈下降趋势,而健侧CBV与正常组比较没有明显改变增高,反映了健侧完善的脑血管的自动调节功能。结论对创伤性脑损伤行动态CTP能够了解脑损伤后的血液流变学规律和脑血管的自动调节机制,为脑外伤后继发性脑损害的救治提供有针对性的实验研究基础。

Objective To investigate the changes of region cerebral homodynamic and cerebral vascular autoregnlation in traumatic brain injury （TBI） by dynamic CT perfusion （CTP） imaging in rat. Methods Forty-five SD rats underwent CTP, including 10 control rats and 35 TBI rats, on 1, 6, 24 h, and day 3, 7, 14, 21 after TBI. The region of interest （ROI） was located near traumatic area within 2 mm and mirror area of relative brain hemisphere. False color pictures and dynamic rCBF, rCBV, MTT and PS were obtained in different time. Pathological examination was also done. Results The rCBF, rCBV on 1 h after TBI was lower than that of control group, and significantly higher on 6 - 24 h after TBI. They reached the peak on day 3. PS had a similar change compared with rCBF, rCBV, but a longer duration. MTT showed to moderate changes except an isolated tide on 3 days after TBI. The rCBF on mirror area of relative brain hemisphere was almost stable except 3 days after TBI, which was lower than that of control group. Meanwhile, the rCBV on mirror area of relative brain hemisphere was normal. Conclusion CTP is an advanced technique to investigate the changes of region cerebral homodynamic and cerebral vascular autoregulation in TBI. The early hypoperfusion and next hyperperfusion around traumatic areas after TBI suggest that the dysfunction of cerebral vascular autoregnlation should be committed to the change of homodynamic in TBI.