Liu Saifeng, Mok Karen, Neelavalli Jaladhar, Cheng Yu-Chung N, Tang Jin, Ye Yongquan, Haacke E Mark
School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.
J Magn Reson Imaging. 2014 Sep;40(3):698-708. doi: 10.1002/jmri.24413. Epub 2013 Oct 31.
To remove the geometry dependence of phase-based susceptibility weighting masks in susceptibility-weighted imaging (SWI) and to improve the visualization of the veins and microbleeds.
True SWI (tSWI) was generated using susceptibility-based masks. Simulations were used to evaluate the influence of the characteristic parameters defining the mask. In vivo data from three healthy adult human volunteers were used to compare the contrast-to-noise-ratios (CNRs) of the right septal vein and the left internal cerebral vein as measured from both tSWI and SWI data. A traumatic brain injury (TBI) patient dataset was used to illustrate qualitatively the proper visualization of microbleeds using tSWI.
Compared with conventional SWI, tSWI improved the CNR of the two selected veins by a factor of greater than three for datasets with isotropic resolution and greater than 30% for datasets with anisotropic resolution. Veins with different orientations can be properly enhanced in tSWI. Furthermore, the blooming artifact due to the strong dipolar phase of microbleeds in conventional SWI was reduced in tSWI for the TBI case.
The use of tSWI overcomes the geometric limitations of using phase and provides better visualization of the venous system, especially for data collected with isotropic resolution.
消除基于相位的敏感性加权掩码在敏感性加权成像（SWI）中的几何依赖性，并改善静脉和微出血灶的可视化效果。
使用基于敏感性的掩码生成真实SWI（tSWI）。通过模拟评估定义掩码的特征参数的影响。使用来自三名健康成年志愿者的体内数据，比较从tSWI和SWI数据测量的右间隔静脉和左大脑内静脉的对比噪声比（CNR）。使用创伤性脑损伤（TBI）患者数据集定性说明使用tSWI对微出血灶的正确可视化。
与传统SWI相比，对于各向同性分辨率的数据集，tSWI将两条选定静脉的CNR提高了三倍以上，对于各向异性分辨率的数据集，提高了30%以上。不同方向的静脉在tSWI中可以得到适当增强。此外，对于TBI病例，tSWI减少了传统SWI中由于微出血灶的强偶极相位导致的光晕伪影。
使用tSWI克服了使用相位的几何限制，并能更好地可视化静脉系统，特别是对于以各向同性分辨率采集的数据。
