论文标题
基于幅度的歧义分离水脂肪分离之后的场不均匀性图的估计
Estimation of Field Inhomogeneity Map Following Magnitude-Based Ambiguity-Resolved Water-Fat Separation
论文作者
论文摘要
目的：使用相位图像扩展基于大小的PDFF（质子密度脂肪分数）和$ r_2^*$映射，以使用相位图像计算现场不均匀性（现场图）。 理论：估计以矩阵形式提出，以最小二乘的意义解决场图。可以使用估计的字段映射更新幅度拟合的PDFF和$ R_2^*$。 方法：评估了我们无素独立实施的量化局限性。 Bland-Altman用于比较我们方法的PDFF和现场图与152名英国生物库受试者（1.5 T Siemens）的基于参考复合物的方法。还使用了单独的采集（3 t siemens）呈现领域不均匀性。 结果：所提出的现场映射的准确性超出了基于复杂的极限范围的两倍。在英国生物库中获得了高度一致性（PDFF偏见= -0.03％，LOA（协议限制）[-0.1,0.1]％;田间映射偏置= 0.06 Hz，LOA = [-0.2,0.3] Hz）。在3 t时观察到稳健的场映射，因为超过300 Hz的不均匀性，包括边缘的快速变化。 结论：在基于幅度的水脂分离之后，通过分离的水脂歧义表现出了场映射，并在高场中显示出潜力。
PURPOSE: To extend magnitude-based PDFF (Proton Density Fat Fraction) and $R_2^*$ mapping with resolved water-fat ambiguity to calculate field inhomogeneity (field map) using the phase images. THEORY: The estimation is formulated in matrix form, resolving the field map in a least-squares sense. PDFF and $R_2^*$ from magnitude fitting may be updated using the estimated field maps. METHODS: The limits of quantification of our voxel-independent implementation were assessed. Bland-Altman was used to compare PDFF and field maps from our method against a reference complex-based method on 152 UK Biobank subjects (1.5 T Siemens). A separate acquisition (3 T Siemens) presenting field inhomogeneities was also used. RESULTS: The proposed field mapping was accurate beyond double the complex-based limit range. High agreement was obtained between the proposed method and the reference in UK Biobank (PDFF bias = -0.03 %, LoA (limits of agreement) [-0.1,0.1] %; Field map bias = 0.06 Hz, LoA = [-0.2,0.3] Hz). Robust field mapping was observed at 3 T, for inhomogeneities over 300 Hz including rapid variation across edges. CONCLUSION: Field mapping following magnitude-based water-fat separation with resolved water-fat ambiguity was demonstrated in-vivo and showed potential at high field.
