Andersson Jonathan, Ahlström Håkan, Kullberg Joel
Section of Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
Section of Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; Antaros Medical, Mölndal, Sweden.
Magn Reson Imaging. 2018 Jul;50:78-83. doi: 10.1016/j.mri.2018.03.015. Epub 2018 Mar 27.
To develop and evaluate a noise-robust method for reconstruction of water and fat images for spoiled gradient multi-echo sequences.
The proposed method performs water-fat separation by using a graph cut to minimize an energy function consisting of unary and binary terms. Spatial smoothing is incorporated to increase robustness to noise. The graph cut can fail to find a solution covering the entire image, in which case the relative weighting of the unary term is iteratively increased until a complete solution is found. The proposed method was compared to two previously published methods. Reconstructions were performed on 16 cases taken from the 2012 ISMRM water-fat reconstruction challenge dataset, for which reference reconstructions were provided. Robustness towards noise was evaluated by reconstructing images with different levels of noise added. The percentage of water-fat swaps were calculated to measure performance.
At low noise levels the proposed method produced similar results to one of the previously published methods, while outperforming the other. The proposed method significantly outperformed both of the previously published methods at moderate and high noise levels.
By incorporating spatial smoothing, an increased robustness towards noise is achieved when performing water-fat reconstruction of spoiled gradient multi-echo sequences.
开发并评估一种用于 spoiled 梯度多回波序列水脂图像重建的抗噪声方法。
所提出的方法通过使用图割来执行水脂分离，以最小化由一元项和二元项组成的能量函数。纳入空间平滑以提高对噪声的鲁棒性。图割可能无法找到覆盖整个图像的解决方案，在这种情况下，一元项的相对权重会迭代增加，直到找到完整的解决方案。将所提出的方法与之前发表的两种方法进行比较。对取自 2012 年 ISMRM 水脂重建挑战数据集的 16 个病例进行重建，该数据集提供了参考重建。通过重建添加了不同噪声水平的图像来评估对噪声的鲁棒性。计算水脂交换的百分比以衡量性能。
在低噪声水平下，所提出的方法产生的结果与之前发表的一种方法相似，同时优于另一种方法。在中等和高噪声水平下，所提出的方法明显优于之前发表的两种方法。
通过纳入空间平滑，在对 spoiled 梯度多回波序列进行水脂重建时可实现对噪声更强的鲁棒性。
