一种表征残肢血管结构变形的参数方法

A parametric method for characterization of deformation in the residuum vasculature

目的论证改进的Hausdorff距离(modified Hausdorff-distance,MH)对残端血管树结构变化的影响规律。方法从CT断层扫描获得临床病例血管模型数据,在MIMICS 10.0中通过设置"控制点间距"(distance between control points,DCP)参数得到残肢血管的中心线模型,在MATLAB软件中编程施加变形,并计算和分析参数MH。根据转轴位置的不同,按照参与变形的血管节点数目、血管总长逐渐增大的顺序,将变形分为C_1、C_2、C_3、C_44种情况。结果 MH随着血管旋转角度的增加而增大,但由于参与变形血管模型的最大旋转半径和血管总长不同,呈现不同的增长趋势。随血管旋转角度增加,MH从C1到C4均逐渐增大,C_2到C_3变化最大,C_3到C_4变化最小。其中,C_2最大旋转半径和血管总长比C_1分别增加了22.2%和91.3%,C_4最大旋转半径和血管总长比C_3分别增加了14.1%和26.8%,而MH则最大变化了60.4%和4.5%。结论 MH可有效表征残端血管结构的变化,可近似认为在残肢中MH与血管变形角度呈正比,且最大旋转半径对MH的影响较大,同时发现DCP<3 mm可有效避免参数设置的影响。另外,MH还可用于其他血管树结构变化和比较的研究。

Objective To demonstrate the relationship between modified Hausdorff distance（ MH） and the spatial change of arterial vasculature in residuum. Methods Data of the vascular model were obtained from CT scans of clinical cases,and a centerline model of the residuum vasculature was established by setting the appropriate parameter of distance between control points（ DCP） in MIMICS 10. 0. Deformation was applied on the model through compiling the program in MATLAB. The MH values before and after the deformation were calculated and analyzed. According to different locations of the rotation axis,the deformation was divided into four cases（ C1,C2,C3,C4） on the basis of growth order in node numbers and total length of the vasculature. Results MH increased with the increment of the vascular rotation angle,but due to different maximum rotation radius and total length of the vascular vessel,4 deformed models showed different growth trends. With the rotation angle increasing,MH gradually increased from C1 to C4. The maximum change occurred from C2 to C3,and minimal change occurred from C3 to C4. Specifically,the maximum rotation radius and total length of the vessels from C1 to C2 increased by 22. 2% and 91. 3%,while those from C3 to C4 increased by 14. 1% and 26. 8%,respectively.Moreover,the maximum change of MH value was 60. 4% from C1 to C2 and 4. 5% from C3 to C4. Conclusions MH can be an effective parameter to indicate spatial change of the residuum vasculature. MH of the residuum vasculature is proportional to deformation angle of the vessel,and the maximum rotation angle has a significant influence on MH. Moreover,when DCP is smaller than 3 mm,the influence of parameter setting can be avoided effectively. In addition,MH can also be applied in the studies of vasculature change and comparison.