灌注造影显微CT三维重建研究骨痂微血管新生

MicroCT based angiography for studying neovascularization of long bone fracture repair in a rat model

目的探讨灌注造影显微CT（MicroCT）扫描三维重建在研究大鼠骨折愈合时骨痂微血管变化的可行性及意义。方法60只雄性Sprague—Dawley（SD）大鼠，随机分为实验组及对照组（每组30只），制作标准的右侧股骨中段闭合骨折模型，术后1、2、3、4、8周处死大鼠。实验组大鼠行腹主动脉远端血管造影后，使用MicroCT断层扫描标本，并选取同一兴趣区测定血管体积、体积分数和血管平均直径。对照组骨痂通过免疫组织化学染色法测定血管内皮生长因子（VEGF）及血管内皮生长因子受体2（VEGFR-2）的表达。结果实验组血管体积、体积分数在术后第3周达到高峰，分别为（196．00±20．33）mm3和（6．70±0．74）％；而血管直径在第4周显著增加，为（109．00±12．15）μm（P〈0．05）。对照组显示VEGF和VEGFR-2的表达在术后第2周明显增加，阳性细胞数分别为113．40±9．17和51．80±4．24（P〈0．05）。结论灌注造影MicroCT扫描三维重建可无创提供直观的高分辨率三维微血管像，并精确定量微血管量与直径。

Objective To explore microcomputed tomography （MicroCT） based angiography for exhibiting the neovascularization/angiogenesis of a callus on a rat femoral fracture model. Methods After a closed fracture establishment, 60 male SD rats were randomized into2 groups （30 in each group）and kill- ed at the time point of 1, 2, 3, 4 and 8 weeks The callus in experimental group were scanned by MicroCT and 3-D vasculature images were reconstructed. Vessel size distribution, total vessel volume and volume fraction were quantified. The callus in control group were assessed by using immunohistochemisty for ob- serving the expression of vascular endothelial growth factor （VEGF） and VEGF receptor 2 （VEGFR-2）. Results MicroCT based angiography provided native 3-D vasculature images to iconicly revea] the states of neovascularization. And the total vessel volume and volume fraction peaked at 3 weeks （ P 〈 0. 05 ） ： （ 196. 00 ± 20. 33 ） mm3 and （ 6. 70 ± 0. 74 ） % respectively; Immunohistochemistry of callus sections showed the expression of VEGF and VEGFR-2 occurred in the early stage of fracture healing and peaked at 2 weeks, the number of positive cells were （ 113.40 ± 9.17 ） and （51.80 ± 4. 24） respectively （ P 〈 0. 05）. Conclusion MicroCT based angiography atraumaticly provided high-resolution, quantitative, 3- dimention, and objective data analysis. MicroCT based angiography is a robust methodology for evaluation of vascular networks in the callus of a small animal.