DANCING WITH THE ELECTRONS: TIME-DOMAIN AND CW IN VIVO EPR IMAGING.
DANCING WITH THE ELECTRONS: TIME-DOMAIN AND CW IN VIVO EPR IMAGING.
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DOI：
10.4137/mri.s1131
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发表时间：
2008-09-24
期刊：
影响因子：
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通讯作者：
Krishna MC
中科院分区：
文献类型：
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作者：
Subramanian S;Krishna MC
利用电子顺磁共振成像（EPRI），对生命系统中未成对电子的分布以及这种成像过程的功能和潜在诊断维度进行成像的发展进展，从其起源开始追溯，重点是我们自己的工作。EPR成像的重要性源于这样一个事实，即许多顺磁探针显示氧依赖性光谱增宽。体内氧浓度的评估是放射肿瘤学治疗计划和监测治疗结果的重要因素。基于窄线三芳基甲基的生物相容性自旋探针的出现使得射频时域EPRI的发展成为可能。时域EPRI中的光谱信息可以通过生成T2* 或T2加权图像的时间序列来实现。CW成像的进步导致了旋转梯度的使用，最近的快速扫描与直接检测，以及所有三种的组合。采用动态核极化（Overhauser效应）的极低场MRI也用于监测体内肿瘤缺氧和再氧合。我们还一直在使用专门设计的谐振器组件在300 MHz下对小鼠肿瘤模型进行MRI和时域EPRI的配准。不成对电子分布的映射和通过使用磁共振在存在静止和旋转梯度的情况下解开光谱特征，实际上是“与（不成对）电子跳舞”，比喻地说。
The progress in the development of imaging the distribution of unpaired electrons in living systems and the functional and the potential diagnostic dimensions of such an imaging process, using Electron Paramagnetic Resonance Imaging (EPRI), is traced from its origins with emphasis on our own work. The importance of EPR imaging stems from the fact that many paramagnetic probes show oxygen dependent spectral broadening. Assessment of in vivo oxygen concentration is an important factor in radiation oncology in treatment-planning and monitoring treatment-outcome. The emergence of narrow-line trairylmethyl based, bio-compatible spin probes has enabled the development of radiofrequency time-domain EPRI. Spectral information in time-domain EPRI can be achieved by generating a time sequence of T2* or T2 weighted images. Progress in CW imaging has led to the use of rotating gradients, more recently rapid scan with direct detection, and a combination of all the three. Very low field MRI employing Dynamic Nuclear polarization (Overhauser effect) is also employed for monitoring tumor hypoxia, and re-oxygenation in vivo. We have also been working on the co-registration of MRI and time domain EPRI on mouse tumor models at 300 MHz using a specially designed resonator assembly. The mapping of the unpaired electron distribution and unraveling the spectral characteristics by using magnetic resonance in presence of stationary and rotating gradients in indeed ‘dancing with the (unpaired) electrons’, metaphorically speaking.