不懂的：

  1. 3DPR, UTE
  2. more twists → fewer total readouts, readout duty cycle, sampling density, SNR efficiency(the loss in SNR as compared to uniform density sampling)
  3. 为什么RES和FOV必须满足这样的条件？

  1. 为什么两条相邻的interleave最短距离要满足 >1/FOV 的条件？

    non-uniform sampling ，no sphere of diameter 1/FOV may be empty

思考：

3D Cone Trajectory优点：

more twists added in trajectory → higher readout time per repetition (readout duty cycle) → higher overall SNR/ fewer total readouts → sampling density uniform, higher SNR efficiency

设计 Trajectory 要考虑的问题：

  1. sufficient to cover the FOV 2. anisotropies (significant anisotropies will add artifacts and increase noise)

BURS , gridding reconstruction

  1. 选择cone surface
  2. 从cone surface上选择trajectory
  3. 从采样间隔角度考虑，计算trajectory上每点的最小斜率
  4. 从硬件角度考虑，gradient coil有gradient 和 slew rate的大小限制

non-uniform data weighting of radial trajectories causes an intrinsic loss in SNR