磁共振弥散加权成像和组织病理学检测深低温停循环动物术后早期脑损伤

Detection of early brain injury in a piglet model after deep hypothermic circulatory arrest with magnetic resonance imaging

目的探讨磁共振弥散加权成像在术后脑损伤中应用价值并分析其与术后动物组织病理学的相关性。方法18只3～5个月中华小型猪，体质量25—30b，分为3组，A组为对照组，仅行全麻，开胸，不进行体外循环；B组在20℃下停循环120rain，术后存活1天；C组20℃下停循环120min，术后存活2天。磁共振弥散加权成像和组织病理学检测深低温停循环术后实验猪脑损伤情况。结果深低温停循环术后动物脑组织新皮质和海马区均可发现苏木精一伊红、原位凋亡阳性细胞。弥散加权成像提示B组有5只动物出现大脑皮质高信号，3只T2WI高信号；C组6只动物均出现大脑皮质高信号，5只T2WI高信号。B、C动物海马区均未发现弥散加权成像高信号。结论磁共振弥散加权成像是一种可靠和无创的检测深低温停循环术后早期脑损伤的方法，优于常规磁共振检查；而且这种损伤主要是大脑皮质受损为主。DHCA术后的MRI和组织病理学检测无很好的相关性。DHCA术后的MRI和组织病理学检测无很好的相关性。

Objective Optimal detection of deep hypothermic circulatory arrest （DHCA）-induced early brain injury is important but the effective technique is still not available in the present. The relationship between diffusion-weighted imaging （DWI） and histopathological changes in DHCA-induced piglet brain injury model were analyzed. Methods Eighteen pigs un- derwent deep hypothermic circulatory arrest and were divided into three groups： group A （ n = 6 ） served as control, only under- went anesthesia and thoracotomy, without extracorporeal circulation. Group B （ n = 6） served as underwent deep hypothermic circulatory arrest at 20 ℃ for 120 rain, survived for 1 day. Group C （n =6） served as underwent deep hypothermic circulatory arrest at 20 ℃ for 120 min, survived for 2 days. Diffusion-weighted imaging and histopathology were used to study the brain injury. Results There were hematoxylin-eosin （ ＋ ） and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling （ ＋ ） cells in cerebral cortex and hippocampus. Hyperintensity was most evident in the cerebral cortex in group B and group C with diffusion-weighted imaging, but it was not seen in hippocampus in both groups. There were 5 and 6 piglets can be seen hy- perintensity with diffusion-weighted imaging sequence in group B and group C respectively. Hyperintensity was also seen in T2WI sequence in 3 and 5 piglets in group B and group C respectively. Conclusion The study demonstrates the feasibility of diffusion-weighted imaging on evaluation of brain injury after deep hypothermic circulatory arrest and cerebral cortex was selec- tively vulnerable to cell injury. It is superior to conventional imaging.