Yim Peter J, Vasbinder G Boudewijn C, Ho Vincent B, Choyke Peter L
Department of Radiology, Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA.
IEEE Trans Med Imaging. 2003 Jul;22(7):875-81. doi: 10.1109/TMI.2003.815056.
Vascular disease produces changes in lumenal shape evident in magnetic resonance angiography (MRA). However, quantification of vascular shape from MRA is problematic due to image artifacts. Prior deformable models for vascular surface reconstruction primarily resolve problems of initialization of the surface mesh. However, initialization can be obtained in a trivial manner for MRA using isosurfaces. We propose a methodology for deforming the isosurface to conform to the boundaries of objects in the image with minimal a priori assumptions of object shape. As in conventional methods, external forces attract the surface toward edges in the image. However, smoothing is produced by a moment that aligns the normals of adjacent surface triangles. Notably, the moment produces no translational motion of surface triangles. The deformable isosurface was applied to a digital phantom of a stenotic artery, to MRA of three renal arteries with atherosclerotic disease and MRA of one carotid artery with atherosclerotic disease. Results of the surface reconstruction from the deformable model were compared with conventional X-ray angiography for the renal arteries. Measurement of the degree of stenosis of the renal arteries was within 12% +/- 6%. The deformable model provided improvements over the isosurface in all cases in terms of measurement of the degree of stenosis or improving the surface smoothness.
血管疾病会导致磁共振血管造影（MRA）中管腔形状发生明显变化。然而，由于图像伪影，从MRA定量血管形状存在问题。先前用于血管表面重建的可变形模型主要解决表面网格初始化的问题。然而，对于MRA，可以使用等值面以简单的方式获得初始化。我们提出了一种方法，用于使等值面变形以符合图像中物体的边界，且对物体形状的先验假设最少。与传统方法一样，外力将表面拉向图像中的边缘。然而，平滑是通过使相邻表面三角形的法线对齐的力矩产生的。值得注意的是，该力矩不会使表面三角形产生平移运动。将可变形等值面应用于狭窄动脉的数字模型、三条患有动脉粥样硬化疾病的肾动脉的MRA以及一条患有动脉粥样硬化疾病的颈动脉的MRA。将可变形模型的表面重建结果与肾动脉的传统X射线血管造影进行比较。肾动脉狭窄程度的测量误差在12%±6%以内。在所有情况下，就狭窄程度的测量或改善表面平滑度而言，可变形模型都比等值面有改进。
