hemorrhage 发表于 2025-3-30 12:06:52
Gradientsng how these different intensities are arranged in space to produce an image. There are a number of ways of doing this, but in this section, we will be concerned only with the most widely used method: two dimensional Fourier transform (“2DFT”) reconstruction.旧石器 发表于 2025-3-30 14:40:40
The Slice Select Gradientdient imposes a gradual change in the main magnetic field from the head to the foot end of the patient. If we graph the z gradient with the magnitude of the magnetic field on the y axis and the position along the long axis of the body on the x axis, then we obtain the straight line shown in the grapenlist 发表于 2025-3-30 18:26:57
The Phase Encoding Gradiention just as we did for the x axis. However, if we did that, then we would not be able to uniquely specify whether a given frequency belonged to the x or the y axis, and the computer would get confused and render us an improper image reconstruction. So we must do something else, and in fact, all comm疲劳 发表于 2025-3-30 23:35:27
http://reply.papertrans.cn/63/6203/620243/620243_54.pngOutmoded 发表于 2025-3-31 03:33:32
http://reply.papertrans.cn/63/6203/620243/620243_55.png