Imaging pH using the chemical exchange saturation transfer (CEST) MRI: Correction of concomitant RF irradiation effects to quantify CEST MRI for chemical exchange rate and pH
Imaging pH using the chemical exchange saturation transfer (CEST) MRI: Correction of concomitant RF irradiation effects to quantify CEST MRI for chemical exchange rate and pH
复制标题
使用化学交换饱和转移 (CEST) MRI 对 pH 进行成像：校正伴随的 RF 辐射效应以量化 CEST MRI 的化学交换率和 pH
DOI：
10.1002/mrm.21653
复制
发表时间：
2008-08-01
影响因子：
3.3
通讯作者：
Sorensen, A. Gregory
中科院分区：
文献类型：
--
作者：
Sun, Phillip Zhe;Sorensen, A. Gregory
化学交换饱和转移（CEST）MRI已显示能够检测稀释的不稳定质子和异常的组织葡萄糖/氧代谢，因此可以用作传统MRI方法的补充成像技术。但是，CEST成像还取决于实验参数，例如辐射RF脉冲的功率，持续时间和波形。结果，其对诸如pH等微环境特性的敏感性和特异性不是最佳的。在这项研究中，解决了CEST对比对实验参数的依赖性，并提出了一种迭代补偿算法，该算法纠正了从随之而来的RF辐照效应中纠正实验测量的CEST对比。通过从组织样pH幻象的数值模拟和实验测量进行了验证所提出的算法，并表明源自补偿的CEST成像的pH与0.1 pH单元中的pH电极测量非常吻合。总而言之，我们的研究验证了校正算法的使用，以补偿与RF辐照效应相关的CEST成像，以准确校准化学汇率，并证明了使用CEST MRI进行pH成像的可行性。
Chemical exchange saturation transfer (CEST) MRI has been shown capable of detecting dilute labile protons and abnormal tissue glucose/oxygen metabolism, and thus, may serve as a complementary imaging technique to the conventional MRI methods. CEST imaging, however, is also dependent on experimental parameters such as the power, duration, and waveform of the irradiation RF pulse. As a result, its sensitivity and specificity for microenvironment properties such as pH is not optimal. In this study, the dependence of CEST contrast on experimental parameters was solved and an iterative compensation algorithm was proposed that corrects the experimentally measured CEST contrast from the concomitant RF irradiation effects. The proposed algorithm was verified with both numerical simulation and experimental measurements from a tissue-like pH phantom, and showed that pH derived from the compensated CEST imaging agrees reasonably well with pH-electrode measurements within 0.1 pH unit. In sum, our study validates the use of a correction algorithm to compensate CEST imaging from concomitant RF irradiation effects for accurate calibration of the chemical exchange rate, and demonstrates the feasibility of pH imaging with CEST MRI.