Analysis of different phase unwrapping methods to optimize quantitative susceptibility mapping in the abdomen
Analysis of different phase unwrapping methods to optimize quantitative susceptibility mapping in the abdomen
复制标题
DOI：
10.1002/mrm.27891
复制
发表时间：
2019-07-17
影响因子：
3.3
通讯作者：
Wittsack, Hans-Joerg
中科院分区：
文献类型：
--
作者：
Bechler, Eric;Stabinska, Julia;Wittsack, Hans-Joerg
目的 定量磁化率绘图 (QSM) 受到梯度回波成像数据的相位处理的严重影响。到目前为止，相位展开算法主要是针对神经成像应用开发和测试的。在这项工作中，创建了一个数字人体腹部模型，并用于评估腹部 QSM 中不同相位展开算法的可行性。此外，还获取了体内数据以评估与模拟的一致性。方法使用数值模型以及体内测量来评估基于拉普拉斯的、质量引导的区域生长和图形切割展开技术。作为质量指标，计算均方根误差 (RMSE)，以分析所检查的展开算法的性能。随后，根据所得相位图生成磁化率图并与地面实况进行比较。对整个模型以及单个器官进行评估。结果 在所研究的展开方法中，图形切割产生了最准确和稳健的结果。其他算法在磁敏度变化较大的区域（即肺部周围）显示出严重错误。对于所有测试的算法，与真实情况敏感性的偏差都高于之前的大脑模拟。结论 在人体腹部的 QSM 研究中，应首选基于图割的展开算法，因为人体腹部会发生较大的磁敏度变化。为了进一步改进 QSM 研究，应针对腹部应用优化展开算法。
Purpose Quantitative susceptibility mapping (QSM) is heavily impacted by phase processing of gradient echo imaging data. So far, phase unwrapping algorithms have mostly been developed and tested for neuroimaging applications. In this work, a numerical human abdomen phantom was created and used to assess the feasibility of different phase unwrapping algorithms in abdominal QSM. Furthermore, in vivo data were acquired to evaluate consistency with the simulations. Methods Laplacian-based, quality-guided region growing and graph-cuts unwrapping techniques were evaluated using the numerical phantom as well as an in vivo measurement. As a quality metric, root mean square error (RMSE) was calculated in order to analyze the performance of the examined unwrapping algorithms. Subsequently, susceptibility maps were generated from the resulting phase maps and compared to the ground truth. The evaluation was carried out on the whole phantom as well as individual organs. Results Graph-cuts led to the most accurate and robust results among the investigated unwrapping methods. The other algorithms showed severe errors in regions with large susceptibility changes (i.e., around the lungs). Deviations from the ground-truth susceptibility were higher than in the previous brain simulations for all tested algorithms. Conclusion Graph-cuts-based unwrapping algorithms should be preferred in QSM studies in the human abdomen, where large susceptibility changes occur. For further improvement of QSM studies, unwrapping algorithms should be optimized for abdominal applications.