Hou Z, Wang R, Ge H, Ju S
Department of Radiology, Zhongda Hospital Affiliated to Southeast University, Nanjing 210009, China.
Nan Fang Yi Ke Da Xue Xue Bao. 2021 Feb 25;41(2):305-309. doi: 10.12122/j.issn.1673-4254.2021.02.21.
To propose a regional iterative phase extraction Dixon method based on second order difference quality weighting (SOD-RIPE) for improving water-lipid separation in heterogeneous magnetic field.
The in-phase angle of the asymmetric in-phase and opposite phase image matrix was eliminated using the Dixon's signal model to obtain and , from which the possible water signal magnitude (B, S) and in-phase and opposite phase difference (, ) was derived using the Cosine law. The phase quality map of was calculated using the second-order difference, and the phase difference was weighted to obtain (, ). The and were iteratively selected to obtain the . The water-fat separation diagram (, ) was obtained using the least square method to bring the into the Dixon signal model.
Water-lipid separation was performed using 1000 pairs of in- and opposite-phase images on a Philips in Genia II 3.0T magnetic resonance scanner. The SOD-RIPE algorithm achieved better separation and stability than the automatic growth method and RIPE in all the parts of the body and in the stability test, and had a similar performance to mDixon-XD algorithm.
SOD-RIPE can achieve robust water-fat separation with a good stability and can be used as a general Dixon water-fat separation method.
提出一种基于二阶差分质量加权的区域迭代相位提取狄克逊方法（SOD-RIPE），以改善非均匀磁场中的水脂分离。
利用狄克逊信号模型消除非对称同相和反相图像矩阵的同相角，得到 和 ，再根据余弦定律从中推导出可能的水信号幅度（B，S）以及同相和反相差分（，）。利用二阶差分计算 的相位质量图，并对相位差进行加权以获得（，）。迭代选择 和 以获得 。使用最小二乘法将 代入狄克逊信号模型，得到水脂分离图（，）。
在飞利浦Genia II 3.0T磁共振扫描仪上使用1000对同相和反相图像进行水脂分离。在身体的所有部位以及稳定性测试中，SOD-RIPE算法比自动生长法和RIPE算法实现了更好的分离和稳定性，并且与mDixon-XD算法具有相似的性能。
SOD-RIPE能够实现稳健的水脂分离，具有良好的稳定性，可作为一种通用的狄克逊水脂分离方法。
