Englmeier K H, Fink U, Haubner M, Becker C, Seemann M, Capeller W, Reiser M
Forschungszentrum für Umwelt und Gesundheit, Institut für Medizinische Informatik und Systemforschung, Oberschleissheim.
Radiologe. 1996 Apr;36(4):360-4. doi: 10.1007/s001170050083.
The objective of this study was to develop a method for 3D subtraction CT angiography and to optimize the visualization after semi-automatic segmentation. Ten patients with aneurysms of the abdominal aorta were examined using spiral CT. To reconstruct the vessels, as well as adjacent organs such as the liver and kidneys, one image data volume was acquired before and after injection of the contrast agent. The CT scans were obtained with a Siemens Somatom Plus 4. To improve the results of automatic segmentation, as well as visualization by maximum intensity projection (i.e. removal of bony structures), subtraction of both image volumes is necessary. However, small translation shifts disturb the subtraction process and produce artificial contours. To calculate the disparities along the three coordinate axes of two corresponding image volumes, a cepstrum filter is applied to a pair of image volumes. After detection of the disparities, which manifest as bright spots, the real shift of the two subsignals can be calculated. Translation of the corresponding image volume pairs to their correct positions improves the subtraction process. In all cases the size of the aneurysm and the abdominal organs could be better segmented and visualized. Application of the cepstrum filter and subtraction of the image volumes before and after contrast medium injection completely removes the bony structures in the image data and results in superior visualization results.
本研究的目的是开发一种三维减影CT血管造影方法，并在半自动分割后优化可视化效果。对10例腹主动脉瘤患者进行螺旋CT检查。为了重建血管以及肝脏和肾脏等相邻器官，在注射造影剂前后采集一个图像数据容积。CT扫描使用西门子Somatom Plus 4进行。为了改善自动分割的结果以及通过最大强度投影进行的可视化（即去除骨骼结构），需要对两个图像容积进行相减。然而，小的平移偏移会干扰相减过程并产生伪轮廓。为了计算两个相应图像容积沿三个坐标轴的视差，将倒谱滤波器应用于一对图像容积。在检测到表现为亮点的视差后，可以计算两个子信号的实际偏移。将相应的图像容积对平移到其正确位置可改善相减过程。在所有情况下，动脉瘤和腹部器官的大小都能得到更好的分割和可视化。应用倒谱滤波器并在注射造影剂前后对图像容积进行相减，可完全去除图像数据中的骨骼结构，并产生更好的可视化效果。
