Motion-insensitive diffusion imaging of the brain using optical tracking and dynamic sequence updates.
Motion-insensitive diffusion imaging of the brain using optical tracking and dynamic sequence updates.
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DOI：
10.1002/mrm.28747
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发表时间：
2021-08
影响因子：
3.3
通讯作者：
Ernst T
中科院分区：
文献类型：
--
作者：
Kaso A;Ernst T
弥散加权成像(DWI)对头部运动非常敏感，运动引起的梯度不平衡可能导致信号丢失。使用快速光学跟踪的预期运动校正可以减弱这些伪影。方法包括准连续更新梯度和RF脉冲或动态施加再平衡梯度以恢复梯度平衡，但这些现有方法使用双极扩散梯度。这个项目的目标是开发和评估更常见的单极扩散序列的运动不敏感实现。在每个RF脉冲和每个扩散加权梯度之前，开发了具有运动更新的单极扩散序列。该序列在体模和人脑中进行了测试，b=1000s/mm~2，旋转速度高达20°/S。比较了有和没有序列内运动更新的扫描的运动敏感度、信号损失和体内图像特征。对于典型的运动参数，采用最优参数的序列内运动更新将运动诱导梯度矩不平衡(DWI)的运动敏感度降低了7倍。通过将脉冲序列的回波时间与跟踪系统帧到帧周期的偶数倍匹配来获得最佳结果。当启用序列内更新时，模体和活体测量中的平均信号损失和信号丢失频率被降低，并且DTI分析的质量测量得到改善。与没有序列内更新的实现相比，单极DWI序列的校正方案可以将脑DWI的运动敏感度降低多达7倍。
Diffusion weighted imaging (DWI) is sensitive to head movements, which may cause signal losses due to motion-induced gradient imbalances. Prospective motion correction using fast optical tracking can attenuate these artifacts. Approaches include quasi-continuous updates of gradients and RF pulses or dynamically applying a rebalancing gradient to restore the gradient balance, but these prior methods used bipolar diffusion gradients. The goal of this project was to develop and evaluate a motion-insensitive implementation for the more common monopolar diffusion sequence. A mono-polar diffusion sequence was developed with motion updates prior to each RF pulse and each diffusion weighting gradient. The sequence was tested in a phantom and human brain, at b=1000s/mm2 and rotational velocities up to 20°/s. Motion sensitivity, signal losses, and in vivo image profiles were compared between scans with and without intra-sequence motion updates. With typical motion parameters, intra-sequence motion updates with optimal parameters reduced the motion-sensitivity of DWI (motion-induced gradient moment imbalance) 7-fold. Optimal results were achieved by matching the echo time of the pulse sequence to an even multiple of the tracking system frame-to-frame period. Average signal losses and the frequency of signal dropouts in phantom and in vivo measurements were reduced when intra-sequence updates were enabled, and quality measures of DTI analyses were improved. A correction scheme for the monopolar DWI sequence can reduce the motion-sensitivity of brain DWI up to 7-fold compared to an implementation without intra-sequence updates.
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影响因子：
3.3
作者：
O'Halloran, R. L.;Holdsworth, S.;Bammer, R.
通讯作者：
Bammer, R.
DOI：
10.1007/s10334-004-0036-x
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2004-05-01
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