A model-based reconstruction for undersampled radial spin-echo DTI with variational penalties on the diffusion tensor.
A model-based reconstruction for undersampled radial spin-echo DTI with variational penalties on the diffusion tensor.
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DOI：
10.1002/nbm.3258
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发表时间：
2015-03
影响因子：
2.9
通讯作者：
Sodickson, Daniel K.
中科院分区：
文献类型：
--
作者：
Knoll, Florian;Raya, Jose G.;Halloran, Rafael O.;Baete, Steven;Sigmund, Eric;Bammer, Roland;Block, Tobias;Otazo, Ricardo;Sodickson, Daniel K.
关键词：
径向自旋回波扩散成像可以对T2值非常低的组织（如关节软骨）进行运动鲁棒成像，具有高空间分辨率和信噪比（SNR）。然而，体内测量具有挑战性，因为自旋回波序列的数据采集速度明显较慢，径向采样的k空间覆盖效率较低，这增加了对欠采样加速协议的需求。本文介绍了一种新的欠采样DTI重构方法。基于模型的重构通过减少优化问题中的未知量来隐式地利用扩散加权图像中的冗余，并通过对扩散张量的元素施加总变分（TV）约束直接在目标定量域中执行压缩感知。对健康志愿者（分别为3例和2例）的各向异性幻肢和膝关节及大脑进行了实验。通过将新方法的重建结果与网格化、并行成像和压缩感知相结合以及最近提出的基于模型的方法进行比较，对新方法进行了评估。实验表明，当使用该方法时，在不引入系统误差的情况下，在减少定量参数图中的噪声和条纹伪影以及减少主特征向量的角色散方面有所改进。这可能会大大减少径向自旋回波扩散张量成像的采集时间，而不会降低参数量化和/或信噪比。
Radial spin echo diffusion imaging allows motion-robust imaging of tissues with very low T2 values like articular cartilage with high spatial resolution and signal-to-noise ratio (SNR). However, in vivo measurements are challenging due to the significantly slower data acquisition speed of spin-echo sequences and the less efficient k-space coverage of radial sampling, which raises the demand for accelerated protocols by means of undersampling. This work introduces a new reconstruction approach for undersampled DTI. A model-based reconstruction implicitly exploits redundancies in the diffusion weighted images by reducing the number of unknowns in the optimization problem and compressed sensing is performed directly in the target quantitative domain by imposing a Total Variation (TV) constraint on the elements of the diffusion tensor. Experiments were performed for an anisotropic phantom and the knee and brain of healthy volunteers (3 and 2 volunteers, respectively). Evaluation of the new approach was conducted by comparing the results to reconstructions performed with gridding, combined parallel imaging and compressed sensing, and a recently proposed model-based approach. The experiments demonstrated improvement in terms of reduction of noise and streaking artifacts in the quantitative parameter maps as well as a reduction of angular dispersion of the primary eigenvector when using the proposed method, without introducing systematic errors into the maps. This may enable an essential reduction of the acquisition time in radial spin echo diffusion tensor imaging without degrading parameter quantification and/or SNR.
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影响因子：
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