Development of L-band Electron Spin Resonance Imaging System for Small Animals

1.电子自旋共振成像系统的构建本项目研制的电子自旋共振成像系统由L波段电子自旋共振光谱仪、场梯度线圈和数据处理器组成。该光谱仪配备了一个环隙谐振器，在回路中有一个电子屏蔽，工作在700-800 NHz，大约30 mT。2.在活体ESR波谱中，使用了几种氮氧自由基，每种都被静脉注射到大鼠体内。鼠头被插入谐振器中。成功地对磁头进行了ESR观测，并获得了具有良好S/N比的光谱。ESR信号随时间衰减。3.电子自旋共振图像(1)二维图像：在生理盐水中，氮氧基-3-氨基甲酰基-2，2，5，5-四甲基吡咯烷-1-氧基(CPROXYL)作为显像剂。Two Dimensi…通过向XY、YZ和ZX平面的投射，可更多地显示自由基在小鼠双腿或大鼠头部的分布。这些图像与受试者体内氮氧自由基的位置和分布很好地对应。(2)ESR-CT图像：大鼠腹腔注射CPROXYL。在横断面(横断面和横断面，层厚1.5 mm)上进行成像。这些图像当之无愧地被冠以ESR-CT的名字。在大鼠头部的横断面图像中，氮氧化物富集区和缺乏区被清晰地区分开来。氮氧化物缺乏区与大鼠脑组织有较好的一致性。由于脑具有血脑屏障，CPROXYL可能被保留在脑内，其在脑内的浓度很低，给出微弱的ESR信号。它在血液中的高浓度给出强烈的ESR信号。我们相信我们的系统已经发展成为L波段的ESR成像系统，可用于含有外源性自由基的大鼠或小鼠的研究。较少

We developed a novel ESR imaging system for rats or mice using the L-band microwave.l.Construction of ESR imaging system The system developed in this project is composed of an L-band ESR spectrometer, a field gradient coil and a data processor. The spectrometer is equipped with a loop-gap resonator having an electric shield in the loop, and is operated at 700-800NHz under ca. 30 mT.2.in vivo ESR spectroscopy Several kinds of nitroxide radicals were used and each was intravenously injected into the rat. The rat head was inserted into the resonator. ESR was successfully observed for the head and obtained the spectra with a good S/N ratio. The ESR signal decayed with time. We showed that the metabolism and /or the excretion in the rat for the nitroixed can be analyzed by the observation of the decay rate.3.ESR imagings (1)Two dimensional images: A nitroxide radical, 3-carbamoyl-2,2,5,5,-tetramethylpyrrolidine- 1-yloxy (CPROXYL), was used as an imaging agent in saline solution. Two dimensi … More onal images of the distribution of the radical in the mouse legs or the rat head were made by the projection to the XY, YZ and ZX planes. The images corresponded well to the location and the distribution of the nitroxide radical in the subjects. (2)ESR-CT images: The rat received the intraperitoneal administration of CPROXYL. The imaging was made on the distribution in the cross sectional plane (horizontal and transaxial, 1.5mm in thickness). The images deserve the name of ESR-CT. In the cross-sectional image of the rat head the nitroxide rich region was clearly distinguished from the deficient region. The nitroxide deficient areas corresponded well to brain of the rat. Since the brain holds the blood brain barrier, CPROXYL may be retained here and its concentration in the brain is quite low, which gives weak ESR signals.Its high concentration in the blood gives strong ESR signals.We believe our system has been well developed as an L-band ESR imaging system and is available to studies on a rat or a mouse containing exsogenous radicals. Less