Panagiotelis I, Nicholson I, Foster M A, Hutchison J M
Department of Bio-Medical Physics and Bio-Engineering, University of Aberdeen, Foresterhill, Aberdeen, UK.
Magn Reson Med. 2001 Dec;46(6):1223-32. doi: 10.1002/mrm.1320.
A novel imaging modality is introduced which uses radiofrequency longitudinally detected electron spin resonance (RF-LODESR). It is capable of providing qualitative and semiquantitative information on a variety of parameters reflecting physiological function, the most significant being tissue oxygenation. Effective spin-lattice (T1e) and spin-spin (T2e) electronic relaxation time maps of the abdomen of living 200-g rats were generated after intravenous administration of a triarylmethyl free radical (TAM). These maps were used to evaluate oxygen distribution. Differences between the liver, kidneys, and bladder were noted. Conclusions were made regarding the distribution, perfusion, and excretion rate of the contrast medium. Ligature-induced anoxia in the kidney was also visualized. LODESR involves transverse ESR irradiation with a modulated excitation, and observing oscillations in the spin magnetization parallel to the main magnetic field. The T1e and T2e maps were calculated from a set of LODESR signal phase images collected at different detection frequencies. Each phase image also provides qualitative information on tissue oxygen levels without any further processing. This method presents an alternative to the conventional transverse ESR linewidth-based oximetry methods, particularly for animal whole-body imaging applications.
一种新型成像方式被引入，它使用射频纵向检测电子自旋共振（RF - LODESR）。它能够提供关于反映生理功能的各种参数的定性和半定量信息，其中最重要的是组织氧合。在静脉注射三芳基甲基自由基（TAM）后，生成了200克活体大鼠腹部的有效自旋 - 晶格（T1e）和自旋 - 自旋（T2e）电子弛豫时间图。这些图用于评估氧分布。注意到肝脏、肾脏和膀胱之间的差异。得出了关于造影剂的分布、灌注和排泄率的结论。肾脏中结扎诱导的缺氧也被可视化。LODESR涉及用调制激发进行横向ESR照射，并观察平行于主磁场的自旋磁化中的振荡。T1e和T2e图是根据在不同检测频率下收集的一组LODESR信号相位图像计算得出的。每个相位图像还提供了关于组织氧水平的定性信息，无需任何进一步处理。这种方法为传统的基于横向ESR线宽的血氧测定方法提供了一种替代方案，特别是对于动物全身成像应用。
