Shi Yilin, Quine Richard W, Rinard George A, Buchanan Laura, Eaton Sandra S, Eaton Gareth R, Epel Boris, Seagle Simone Wanless, Halpern Howard J
Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO, 80210, USA.
School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO, 80210, USA.
Adv Exp Med Biol. 2017;977:327-334. doi: 10.1007/978-3-319-55231-6_43.
The triarylmethyl radical OX063d24 is currently used for pulsed electron paramagnetic resonance oximetry at 250 MHz. Both 1/T and 1/T increase with increasing oxygen concentration. The dependence of 1/T on probe concentration is smaller than for 1/T . To inform the selection of the optimum frequency for in vivo oximetry 1/T , 1/T and signal-to-noise were measured as a function of frequency between 400 and 1000 MHz on a variable-frequency spectrometer with an adjustable-frequency cross-loop resonator. 1/T and 1/T decrease with increasing frequency and signal-to-noise increases with increasing frequency, which are all favourable for imaging at higher frequencies. However, depth of penetration of the radio frequency (RF) into an animal decreases with increasing frequency. Assuming that the RF loss in the animal to be studied determines the resonator Q, our results indicate that the optimum frequency for in vivo imaging will be determined by the desired depth of penetration in the tissue.
三芳基甲基自由基OX063d24目前用于250 MHz的脉冲电子顺磁共振血氧测定法。1/T和1/T均随氧浓度的增加而增加。1/T对探针浓度的依赖性小于1/T。为了确定体内血氧测定的最佳频率，在具有可调频率交叉环谐振器的可变频率光谱仪上，测量了400至1000 MHz之间频率函数的1/T、1/T和信噪比。1/T和1/T随频率增加而降低，信噪比随频率增加而增加，这些都有利于在更高频率下成像。然而，射频（RF）在动物体内的穿透深度随频率增加而减小。假设待研究动物体内的RF损耗决定了谐振器的Q值，我们的结果表明，体内成像的最佳频率将由组织中所需的穿透深度决定。
