Schreiner S, Paschal C B, Galloway R L
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
J Comput Assist Tomogr. 1996 Jan-Feb;20(1):56-67. doi: 10.1097/00004728-199601000-00012.
Four methods of producing maximum intensity projection (MIP) images were studied and compared.
Three of the projection methods differ in the interpolation kernel used for ray tracing. The interpolation kernels include nearest neighbor interpolation, linear interpolation, and cubic convolution interpolation. The fourth projection method is a voxel projection method that is not explicitly a ray-tracing technique. The four algorithms' performance was evaluated using a computer-generated model of a vessel and using real MR angiography data. The evaluation centered around how well an algorithm transferred an object's width to the projection plane.
The voxel projection algorithm does not suffer from artifacts associated with the nearest neighbor algorithm. Also, a speed-up in the calculation of the projection is seen with the voxel projection method. Linear interpolation dramatically improves the transfer of width information from the 3D MRA data set over both nearest neighbor and voxel projection methods. Even though the cubic convolution interpolation kernel is theoretically superior to the linear kernel, it did not project widths more accurately than linear interpolation. A possible advantage to the nearest neighbor interpolation is that the size of small vessels tends to be exaggerated in the projection plane, thereby increasing their visibility.
The results confirm that the way in which an MIP image is constructed has a dramatic effect on information contained in the projection. The construction method must be chosen with the knowledge that the clinical information in the 2D projections in general will be different from that contained in the original 3D data volume.
研究并比较生成最大强度投影（MIP）图像的四种方法。
其中三种投影方法在用于光线追踪的插值内核方面有所不同。插值内核包括最近邻插值、线性插值和三次卷积插值。第四种投影方法是一种体素投影方法，它并非明确的光线追踪技术。使用计算机生成的血管模型以及真实的磁共振血管造影（MR angiography）数据对这四种算法的性能进行评估。评估主要围绕算法将物体宽度传递到投影平面的效果展开。
体素投影算法不存在与最近邻算法相关的伪影。此外，体素投影方法在投影计算速度上有所提升。与最近邻和体素投影方法相比，线性插值显著改善了从三维磁共振血管造影数据集传递宽度信息的效果。尽管三次卷积插值内核在理论上优于线性内核，但它在投影宽度方面并不比线性插值更准确。最近邻插值的一个可能优势在于，在投影平面中小血管的尺寸往往会被夸大，从而提高了它们的可见性。
结果证实，构建MIP图像的方式对投影中包含的信息有显著影响。在选择构建方法时必须认识到，二维投影中的临床信息通常会与原始三维数据体中包含的信息有所不同。
