A novel phase-unwrapping method based on pixel clustering and local surface fitting with application to Dixon water-fat MRI
A novel phase-unwrapping method based on pixel clustering and local surface fitting with application to Dixon water-fat MRI
复制标题
基于像素聚类和局部表面拟合的新型相位展开方法及其在 Dixon 水脂 MRI 中的应用
DOI：
10.1002/mrm.26647
复制
发表时间：
2018-01-01
影响因子：
3.3
通讯作者：
Feng, Yanqiu
中科院分区：
文献类型：
--
作者：
Cheng, Junying;Mei, Yingjie;Feng, Yanqiu
PurposeTo开发和评估一种新的2D相位展开方法，在存在严重的噪声，快速的相位变化，和断开regions.Theory和MethodsThe MR相位图通常迅速变化，在附近的区域包裹的存在下，强大的工作。相反，相量可以缓慢变化，特别是在远离组织边界的区域中。基于这一观察，本文开发了一种相位展开方法，通过使用像素聚类和局部曲面拟合（CLOSE）的方法，利用相位和相量数据之间的不同的局部变化特性。CLOSE方法首先将像素分为容易展开的块和难以展开的残留像素，然后通过区域生长表面拟合方法依次执行块内、块间和残留像素相位展开。结果在模拟实验中，CLOSE方法对信噪比为0.5、相位变化大于0、不连续区域的平均误差率小于1.50%，与相位区域扩展标签展开离散估计（PRELUDE）方法进行了比较。对350幅膝关节和踝关节活体图像，CLOSE算法的水脂交换率为4.29%，而PRELUDE算法的水脂交换率为25.71%。结论CLOSE算法能够正确地进行相位解缠，具有较高的鲁棒性，有利于需要相位解缠的MRI应用。Magn Reson Med 79：515-528，2018。(c)2017年国际医学磁共振学会。
PurposeTo develop and evaluate a novel 2D phase-unwrapping method that works robustly in the presence of severe noise, rapid phase changes, and disconnected regions.Theory and MethodsThe MR phase map usually varies rapidly in regions adjacent to wraps. In contrast, the phasors can vary slowly, especially in regions distant from tissue boundaries. Based on this observation, this paper develops a phase-unwrapping method by using a pixel clustering and local surface fitting (CLOSE) approach to exploit different local variation characteristics between the phase and phasor data. The CLOSE approach classifies pixels into easy-to-unwrap blocks and difficult-to-unwrap residual pixels first, and then sequentially performs intrablock, interblock, and residual-pixel phase unwrapping by a region-growing surface-fitting method. The CLOSE method was evaluated on simulation and in vivo water-fat Dixon data, and was compared with phase region expanding labeler for unwrapping discrete estimates (PRELUDE).ResultsIn the simulation experiment, the mean error ratio by CLOSE was less than 1.50%, even in areas with signal-to-noise ratio equal to 0.5, phase changes larger than , and disconnected regions. For 350 in vivo knee and ankle images, the water-fat swap ratio of CLOSE was 4.29%, whereas that of PRELUDE was 25.71%.ConclusionsThe CLOSE approach can correctly unwrap phase with high robustness, and benefit MRI applications that require phase unwrapping. Magn Reson Med 79:515-528, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.