Clinical application of reconstructed three dimensional magnetic resonance imaging in cardiovascular diseases.

为了评估心血管解剖，我们在下一台工作站上开发了一种使用磁共振(MR)成像数据的低成本三维(3D)重建系统。这个系统的前一个版本有几个问题。重建全心脏和大血管需要多层螺旋CT扫描，由于采用多层螺旋CT自旋回波技术的多层螺旋CT门控成像，不能自然重建主动脉弓、肺动脉等弯曲或曲折的结构。没有看到其他结构后面的结构。为了解决这些问题，我们使用轴位、冠状位和矢状位图像来减少每个方向上的切片数目，改进模压技术以自然重建弯曲或弯曲的结构，并应用半透明技术来评估重叠的结构。通过输入切片数目、切片厚度、切片间的间隙厚度和每个方向图中第一个切片的位置数据来确定三个轴位数据中的空间位置。为了改进建模，通过三维空间曲线连接轮廓的几何中心，并确定每个心脏结构的中心轴。将轮廓投影到与中心轴垂直的平面上，并进行半自动处理，直到得到一个像素的轮廓。然后进行具有透明度的表面绘制，并将每个结构进行叠加。我们在环主动脉扩张症和矫正的大动脉转位的患者中尝试了这些改进的技术。通过这些改进，可以自然地重建弯曲或弯曲的结构，并能很好地评估叠加结构。由于我们可以在每个方向上以较少的切片数重建三维图像，因此使用常规MR检查的数据重建三维图像成为可能。

To assess the cardiovascular anatomy, we have developed a low cost three dimensional (3D) reconstruction system using magnetic resonance (MR) imaging data on a NeXT workstation. The former version of this system had several problems. It needed many slices to reconstruct the whole heart and great vessels because we used multisectional and multiphasic EGG-gated MR images by the spin-echo technique in the only axial view, It was not able to reconstruct naturally the curved or meandered structures such as the aortic arch and the pulmonary artery. The structures behind other structures were not seen. To conqure these problem, we used axial, coronal and sagittal images to reduced the number of slices in each directional view, improved the moleling technique to reconstruct the curved or meandered structures naturally and applied the partly transparent technique to evaluate the overlapped structures. Determination of spacial location in the data of three axis views were done by entering the number of slices, slice thickness, gap thickness between the slices and the locational data of the first slice in each directional view. In order to improve the modeling, geometric centers of the coutours were connected by a 3D space curve, and the central axis of each cardiac structure was determined. The contours are projected on the perpendicular plane to the central axis and semiautomatically processed until the contours of one pixel are obtained. Then the surface rendering with transparency was performed and the each structures were superimposed. We tried these modified technique in patients with annuloaortic ectasia and corrected transposition of the greatarteries. With these improvement the curved or meandered structures were reconstructed naturally and superimposed structures were evaluated well.As we can reconstruct 3D images well with less number of slices in each directional view, it becomes possible to reconstruct 3D images with using the data of a routine MR examination.