Lee J N, Riederer S J, Bobman S A, Farzaneh F, Wang H Z
Magn Reson Med. 1986 Feb;3(1):33-43. doi: 10.1002/mrm.1910030106.
MR image synthesis has previously been developed as a means of retrospectively optimizing contrast of arbitrary materials in MR images. The first step of this process is to form computed N(H), T1, and T2 images from source images acquired at a variety of echo delay and repetition times. The second step is to take these computed images, along with operator-selected timing parameters, and mathematically generate a synthesized image. Computation is carried out pixel by pixel according to the equation describing the chosen pulse sequence. This paper presents a study of design considerations for a digital image processor capable of rapidly performing the second step, the actual synthesis. In this work the computations inherent to image synthesis are identified, and the feasibility of performing them in high-speed hardware examined. An analysis of the imprecision due to bit-limited calculations shows that an error bound of 0.4% is possible with a 16-bit processor design. A method is described which uses a commercially available image processor by which images can be synthesized according to any of the standard pulse sequences in less than 600 ms.
磁共振成像（MR）图像合成技术此前已被开发出来，作为一种回顾性优化MR图像中任意物质对比度的手段。该过程的第一步是根据在各种回波延迟和重复时间采集的源图像，生成计算得到的N(H)、T1和T2图像。第二步是将这些计算得到的图像与操作员选择的定时参数一起，通过数学方法生成合成图像。根据描述所选脉冲序列的方程逐像素进行计算。本文介绍了一种对能够快速执行第二步（即实际合成）的数字图像处理器的设计考量研究。在这项工作中，确定了图像合成所固有的计算，并研究了在高速硬件中执行这些计算的可行性。对因有限位计算导致的不精确性分析表明，采用16位处理器设计时，误差界限可达0.4%。本文描述了一种方法，该方法使用市售图像处理器，可在不到600毫秒的时间内根据任何标准脉冲序列合成图像。
