Wang Dinghui, Zwart Nicholas R, Li Zhiqiang, Schär Michael, Pipe James G
Barrow Neurological Institute, Phoenix, Arizona, USA.
Philips Healthcare, Cleveland, OH, USA.
Magn Reson Med. 2016 Feb;75(2):627-38. doi: 10.1002/mrm.25620. Epub 2015 Mar 11.
The goal of this work is to present a new three-point analytical approach with flexible even or uneven echo increments for water-fat separation and to evaluate its feasibility with spiral imaging.
Two sets of possible solutions of water and fat are first found analytically. Then, two field maps of the B0 inhomogeneity are obtained by linear regression. The initial identification of the true solution is facilitated by the root-mean-square error of the linear regression and the incorporation of a fat spectrum model. The resolved field map after a region-growing algorithm is refined iteratively for spiral imaging. The final water and fat images are recalculated using a joint water-fat separation and deblurring algorithm.
Successful implementations were demonstrated with three-dimensional gradient-echo head imaging and single breathhold abdominal imaging. Spiral, high-resolution T1 -weighted brain images were shown with comparable sharpness to the reference Cartesian images.
With appropriate choices of uneven echo increments, it is feasible to resolve the aliasing of the field map voxel-wise. High-quality water-fat spiral imaging can be achieved with the proposed approach.
本研究的目的是提出一种新的三点分析方法，该方法具有灵活的偶数或奇数回波增量，用于水脂分离，并通过螺旋成像评估其可行性。
首先通过解析方法找到两组水和脂肪的可能解。然后，通过线性回归获得两组B0不均匀性的场图。线性回归的均方根误差和脂肪谱模型的纳入有助于对真实解进行初始识别。对区域生长算法后的解析场图进行迭代细化，以用于螺旋成像。使用联合水脂分离和去模糊算法重新计算最终的水和脂肪图像。
通过三维梯度回波头部成像和单次屏气腹部成像展示了成功的实施。螺旋高分辨率T1加权脑图像显示出与参考笛卡尔图像相当的清晰度。
通过适当选择不均匀回波增量，逐体素解析场图的混叠是可行的。使用所提出的方法可以实现高质量的水脂螺旋成像。
