Advantageous application of a surface coil to EPR irradiation in Overhauser-enhanced MRI
Advantageous application of a surface coil to EPR irradiation in Overhauser-enhanced MRI
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DOI：
10.1002/mrm.21198
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发表时间：
2007-04-01
影响因子：
3.3
通讯作者：
Utsumi, Hideo
中科院分区：
文献类型：
--
作者：
Matsumoto, Shingo;Yamada, Kenichi;Utsumi, Hideo
本文介绍了表面线圈在奥弗豪斯增强核磁共振（OMRI）中电子顺磁共振（EPR）照射中的优势应用。OMRI是一种基于Over-hauser效应的双共振自由基成像方法。质子核磁共振图像记录没有和有EPR辐照自由基共振，这导致质子图像的差异，显示信号增强的空间区域包含自由基。为了在OMRI中获得良好的信号增强，需要非常高的射频功率和较长的EPR照射时间。为了提高灵敏度和缩短图像采集时间，特别是对于局部（和局部）应用，我们开发并测试了一种表面线圈型EPR辐照线圈。理论计算和实验数据表明，EPR辐照表面线圈可以改善局部Overhauser增强，这与感兴趣区域（ROI）表面线圈/B-1体积线圈的比值有关。灵敏度的提高也可以转化为EPR辐照时间的缩短，从而实现快速的数据采集。对于生物医学应用，使用表面线圈（而不是传统的体积线圈）可以减少样品中获得相同的ROI增强所需的总RF功率沉积。
The present study describes the advantageous application of a surface coil to electron paramagnetic resonance (EPR) irradiation in Overhauser-enhanced MRI (OMRI). OMRI is a double-resonance method for imaging free radicals based on the Over-hauser effect. Proton NMR images are recorded without and with EPR irradiation of the free radical resonance, which results in a difference proton image that shows signal enhancement in spatial regions that contain the free radical. To obtain good signal enhancement in OMRI, very high RF power and a long EPR irradiation time are required. To improve sensitivity and shorten the image acquisition time, especially for localized (and topical) applications, we developed and tested a surface-coil-type EPR irradiation coil. Theoretical calculations and experimental data showed that EPR irradiation through the surface coil could ameliorate the localized Overhauser enhancement, which was related to the ratio of 8, surface coil/B-1 volume coil in the region of interest (ROI), as expected. The increased sensitivity could also be converted into a shortened EPR irradiation time, resulting in fast data acquisition. For biomedical applications, the use of a surface coil (as opposed to a conventional volume coil) could decrease the total RF power deposition in the sample required to obtain the same Overhauser enhancement in the ROI.