Centering the projection reconstruction trajectory: Reducing gradient delay errors
Centering the projection reconstruction trajectory: Reducing gradient delay errors
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DOI：
10.1002/mrm.10501
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发表时间：
2003-07-01
影响因子：
3.3
通讯作者：
McVeigh, ER
中科院分区：
文献类型：
--
作者：
Peters, DC;Derbyshire, JA;McVeigh, ER
研究了投影重建（PR）轨迹中各物理梯度的实际起始时间与请求起始时间之间的梯度时间延迟的影响。用延迟梯度构造的径向轨迹以角度依赖的方式错过k空间的中心，导致有效回波时间随投影角度变化。在幻影中测量了梯度定时延迟，揭示了x， y和z梯度上的延迟相差高达5 μ m。使用这种一次性校准测量，通过向逻辑x和y读出梯度的预相器添加补偿梯度区域来校正轨迹的梯度延迟。在所有成像方向上，有效投影到投影的回波时间变异性降低到小于1毫秒。通过校正轨迹，在幻影图像和志愿者研究中减少了伪影。这种矫正应该会增强PR轨迹的临床应用。中华医学杂志，2003。2003年Wiley-Liss出版社出版。
The projection reconstruction (PR) trajectory was investigated for the effect of gradient timing delays between the actual and requested start time of each physical gradient. Radial trajectories constructed with delayed gradients miss the center of k-space in an angularly dependent manner, causing effective echo times to vary with projection angle. The gradient timing delays were measured in phantoms, revealing delays on the x, y, and z gradients which differed by as much as 5 musec. Using this one-time calibration measurement, the trajectories were corrected for gradient delays by addition of compensatory gradient areas to the prephasers of the logical x and y readout gradients. Effective projection-to-projection echo time variability was reduced to less than 1 musec for all imaging orientations. Using corrected trajectories, artifacts were reduced in phantom images and in volunteer studies. This correction should potentiate greater clinical use of the PR trajectory. Magn Reson Med 50:1-6, 2003. Published 2003 Wiley-Liss, lnc.