Amide proton transfer imaging with improved robustness to magnetic field inhomogeneity and magnetization transfer asymmetry using saturation with frequency alternating RF irradiation.
Amide proton transfer imaging with improved robustness to magnetic field inhomogeneity and magnetization transfer asymmetry using saturation with frequency alternating RF irradiation.
复制标题
DOI：
10.1002/mrm.22912
复制
发表时间：
2011-11
影响因子：
3.3
通讯作者：
Alsop, David C.
中科院分区：
文献类型：
--
作者：
Scheidegger, Rachel;Vinogradov, Elena;Alsop, David C.
关键词：
酰胺质子转移(APT)成像作为组织酸碱度的指示剂和脑肿瘤的标志物已显示出良好的前景。APT测量的误差来源包括直接水饱和度以及膜和大分子的磁化传递(MT)。这些通常通过后处理不对称分析来抑制。然而，这种方法强烈依赖于B0的均匀性，并可能由于固有的MT不对称性、与酰胺峰相反的脂族质子特征以及辐射衰减引起的不对称性而引入额外的误差。虽然有几种方法可以校正B0不均匀性，但它们极大地增加了扫描时间，并且不能解决由z谱的不对称性引起的误差。本文提出了一种新的饱和方案-频率交变射频辐照饱和(SAFARI)，并结合一个新的磁化传递比(MTR)参数，即使在存在B0不均匀的情况下，也可以生成对直接水饱和度和MT不敏感的APT图像。狩猎技术的可行性在幻影和人脑中得到了证明。实验结果表明，Safari算法成功地去除了APT图像中的直接含水饱和度和MT污染。它对高达180赫兹的B0偏移量不敏感，无需使用额外的B0校正，从而大大缩短了扫描时间。
Amide proton transfer (APT) imaging has shown promise as an indicator of tissue pH and as a marker for brain tumors. Sources of error in APT measurements include direct water saturation, and magnetization transfer (MT) from membranes and macromolecules. These are typically suppressed by post-processing asymmetry analysis. However, this approach is strongly dependent on B0 homogeneity and can introduce additional errors due to intrinsic MT asymmetry, aliphatic proton features opposite the amide peak, and radiation damping-induced asymmetry. Although several methods exist to correct for B0 inhomogeneity, they tremendously increase scan times and do not address errors induced by asymmetry of the z-spectrum. In this paper, a novel saturation scheme - saturation with frequency alternating RF irradiation (SAFARI) - is proposed in combination with a new magnetization transfer ratio (MTR) parameter designed to generate APT images insensitive to direct water saturation and MT, even in the presence of B0 inhomogeneity. The feasibility of the SAFARI technique is demonstrated in phantoms and in the human brain. Experimental results show that SAFARI successfully removes direct water saturation and MT contamination from APT images. It is insensitive to B0 offsets up to 180Hz without using additional B0 correction, thereby dramatically reducing scanning time.
登录
查看更多内容
影响因子：
15
作者：
Friedman, Joshua I.;McMahon, Michael T.;Stivers, James T.;Van Zijl, Peter C. M.
通讯作者：
Van Zijl, Peter C. M.
影响因子：
2.2
作者：
Avni, Reut;Mangoubi, Oren;Frydman, Ludo
通讯作者：
Frydman, Ludo
影响因子：
2.9
作者：
Grande, Sveva;Luciani, Anna Maria;Viti, Vincenza
通讯作者：
Viti, Vincenza
影响因子：
3.3
作者：
Kim M;Gillen J;Landman BA;Zhou J;van Zijl PC
通讯作者：
van Zijl PC
影响因子：
3.3
作者：
Mori, S;Eleff, SM;van Zijl, PCM
通讯作者：
van Zijl, PCM