Fat separation using grid fit method at high-field MRI

In high-field magnetic resonance imaging (MRI), water-fat separation in the presence of B0 field inhomogeneity is important research. Various field map estimation techniques that use three-point multi-echo acquisitions have been developed for reliable water fat separation. Among the numerous techniques, iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) has gained considerable popularity as an iterative method for acquiring high-quality water and fat images. However, due to the worsened B0 in homogeneity at high-field, IDEAL cannot adjust for meaningful field map estimation, particularly for a large field of view. Previously, to improve the robustness of this estimation, a region-growing (RG) technique was developed to take advantage of the 2D linear extrapolation procedure through the seed point set by the median value in the target object. There are some limitations with this approach, such as the dependence on the initial seed point, such as a number, intensity, and position of the seed point. In this work, we introduce a effective method called the improved Grid-fit method that does not need to consider parameters related with accuracy. As a result of the proposed method, we obtained a effective fat quantification result that can be applied in high-fields, with an average water residual rate of 7.2% higher than the existing method.