Nyúl L G, Udupa J K, Zhang X
IEEE Trans Med Imaging. 2000 Feb;19(2):143-50. doi: 10.1109/42.836373.
One of the major drawbacks of magnetic resonance imaging (MRI) has been the lack of a standard and quantifiable interpretation of image intensities. Unlike in other modalities, such as X-ray computerized tomography, MR images taken for the same patient on the same scanner at different times may appear different from each other due to a variety of scanner-dependent variations and, therefore, the absolute intensity values do not have a fixed meaning. We have devised a two-step method wherein all images (independent of patients and the specific brand of the MR scanner used) can be transformed in such a way that for the same protocol and body region, in the transformed images similar intensities will have similar tissue meaning. Standardized images can be displayed with fixed windows without the need of per-case adjustment. More importantly, extraction of quantitative information about healthy organs or about abnormalities can be considerably simplified. This paper introduces and compares new variants of this standardizing method that can help to overcome some of the problems with the original method.
磁共振成像（MRI）的一个主要缺点是缺乏对图像强度的标准且可量化的解释。与其他成像方式不同，例如X射线计算机断层扫描，同一患者在同一台扫描仪上于不同时间拍摄的MR图像，由于各种与扫描仪相关的变化，可能彼此看起来不同，因此绝对强度值没有固定的意义。我们设计了一种两步法，通过这种方法，所有图像（与患者以及所使用的MR扫描仪的特定品牌无关）都可以进行变换，使得对于相同的协议和身体区域，在变换后的图像中，相似的强度将具有相似的组织意义。标准化图像可以用固定窗口显示，无需针对每个病例进行调整。更重要的是，关于健康器官或异常情况的定量信息提取可以大大简化。本文介绍并比较了这种标准化方法的新变体，这些变体有助于克服原始方法的一些问题。
