Wen Yan, Wang Yi, Liu Tian
MedImageMetric LLC, New York, New York, USA.
Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
Magn Reson Med. 2016 Feb;75(2):823-30. doi: 10.1002/mrm.25652. Epub 2015 Mar 7.
The inversion from the magnetic field to the magnetic susceptibility distribution is ill-posed because the dipole kernel, which relates the magnetic susceptibility to the magnetic field, has zeroes at a pair of cone surfaces in the k-space, leading to streaking artifacts on the reconstructed quantitative susceptibility maps (QSM). A method to impose consistency on the cone data (CCD) with structural priors is proposed to improve the solutions of k-space methods.
The information in the cone region is recovered by enforcing structural consistency with structural prior, while information in the noncone trust region is enforced to be consistent with the magnetic field measurements in k-space. This CCD method was evaluated by comparing the initial results of existing QSM algorithms to the QSM results after CCD enhancement with respect to the COSMOS results in simulation, phantom, and in vivo human brain.
The proposed method demonstrated suppression of streaking artifacts and the resulting QSM showed better agreement with reference standard QSM compared with other k-space based methods.
By enforcing consistency with structural priors in the cone region, the missing data in the cone can be recovered and the streaking artifacts in QSM can be suppressed.
从磁场到磁化率分布的反演是不适定的，因为将磁化率与磁场相关联的偶极核在k空间中的一对锥面上存在零点，这会导致在重建的定量磁化率图（QSM）上出现条纹伪影。提出了一种利用结构先验对锥数据（CCD）施加一致性的方法，以改进k空间方法的解。
通过与结构先验强制结构一致性来恢复锥区域中的信息，同时强制非锥信任区域中的信息与k空间中的磁场测量结果一致。通过将现有QSM算法的初始结果与在模拟、体模和体内人脑方面相对于COSMOS结果进行CCD增强后的QSM结果进行比较，对这种CCD方法进行了评估。
所提出的方法显示出对条纹伪影的抑制作用，并且与其他基于k空间的方法相比，所得的QSM与参考标准QSM显示出更好的一致性。
通过在锥区域中与结构先验强制一致性，可以恢复锥中的缺失数据并抑制QSM中的条纹伪影。
