应用图像后处理技术测量和分析人体颈动脉分叉血管几何学指标

Measurement and analysis of geometric parameters of human carotid bifurcation using image post- processing technique

目的初步应用MR血管影像结合计算机三维图像后处理技术测量和分析在体颈动脉分叉的几何学属性指标，探讨不同年龄组该段血管形态的差异。方法搜集2005年至2007年经超声检查或DSA检查证实为颈动脉分叉正常或狭窄率小于30％的受检者57例，分为≤40岁组27例和〉40岁组30例，行颈动脉MR增强血管成像（CEMRA）检查，扫描所得减影图像经计算机图像后处理重建三维血管图像并测量颈动脉分叉的各项几何学指标。采用嵌套设计方差分析方法分析两组的各项测量指标的差异是否有统计学意义。结果〉40岁组和≤40岁组的颈动脉分叉几何学指标分别为：分叉角：70．268°±16．050°和58．857°±13．294°，颈内动脉（ICA）角：36．893°±11．837°和30．275°±9．533°，ICA非平面角：6．453°±5．009°和6．263°±4．250°，颈总动脉（CCA）曲率：0．023±0．011和0．014±0．005，ICA曲率：0．070±0．042和0．046±0．022，ICA／CCA直径比：0．693±0．132和0．728±0．106，颈外动脉（ECA）／CCA直径比：0．750±0．123和0．809±0．122，ECA／ICA直径比：1．103±0．201和1．127±0．195；分叉面积比：1．057±0．281和1．291±0．252。〉40岁组和≤40岁组的分叉角、ICA角、CCA曲率、ICA曲率、ECA／CCA直径比和分叉面积比的差异有统计学意义（F值分别为17．16、11．74、23．02、13．38、6．54、22．80，P值均〈0．05）。结论应用MR血管成像结合图像后处理方法实现了在体颈动脉分叉的三维立体重组和其各项几何学指标的测量，为进一步分析血管几何形态与血流动力学状态的关系以及其与动脉粥样硬化病变的发生与发展提供了一种崭新而简便易行的技术。

Objective To investigate variation in the carotid bifurcation geometry of adults of different age by MR angiography images combining image post-processing technique. Methods Images of the carotid bifurcations of 27 young adults （ ≤40 years old） and 30 older subjects （ 〉40 years old） were acquired via contrast-enhanced MR angiography. Three dimensional （3D） geometries of the bifurcations were reconstructed and geometric parameters were measured by post-processing technique. Results The geometric parameters of the young versus older groups were as follows： bifurcation angle （70. 268°± 16. 050 ° versus 58. 857 ° ± 13. 294 ° ）, ICA angle （36. 893 ° ± 11. 837 ° versus 30. 275 °± 9. 533 ° ）, ICA planarity （6. 453° ± 5. 009° versus 6. 263° ± 4. 250°） , CCA tortuosity （0. 023 ± 0. 011 versus 0. 014 ± 0. 005）, ICA tortuosity （ 0. 070 ± 0. 042 versus 0. 046 ± 0. 022 ）, ICA/CCA diameter ratio （ 0. 693 ± 0. 132 versus 0. 728± 0. 106）, ECA/CCA diameter ratio （0. 750 ± 0. 123 versus 0. 809 ± 0. 122）, ECA/ ICA diameter ratio （1. 103±0. 201 versus 1. 127 ± 0. 195）, bifurcation area ratio （1. 057 ± 0. 281 versus 1. 291 ± 0. 252 ）. There was significant statistical difference between young group and older group in bifurcation angle, ICA angle, CCA tortuosity, ICA tortuosity, ECA/CCA and bifurcation area ratio （ F = 17.16,11.74,23.02,13.38,6. 54,22. 80,respectively, P 〈0. 05）. Conclusions MR angiography images combined with image post-processing technique can reconstruct 3D carotid bifurcation geometry and measure the geometric parameters of carotid bifurcation in vivo individually. It provides a new and convenient method to investigate the relationship of vascular geometry and flow condition with atherosclerotic pathological changes.