Sato-Akaba Hideo, Emoto Miho C, Fujii Hirotada G
Department of Electrical and Electronic Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, Japan.
Department of Clinical Laboratory Science, School of Medical Technology, Health Sciences University of Hokkaido, Sapporo, Japan.
Magn Reson Med. 2025 Jul;94(1):424-435. doi: 10.1002/mrm.30432. Epub 2025 Jan 20.
Redox homeostasis plays a key role in regulating the overall health and development of organisms. This study aimed to develop a compact and mobile continuous-wave (CW) electron paramagnetic resonance (EPR) imager to facilitate stable, highly sensitive fast three-dimensional (3D) whole-body imaging of nitroxide-infused mice.
A multiturn loop gap resonator with a diameter of 30 mm and length of 35 mm was designed for whole-body EPR imaging. A compact and mobile CW-EPR imager operating at 750 MHz was developed using this resonator. The automatic matching and tuning control systems were also adjusted to compensate for perturbations caused by the movement of the mice.
When the mice were inserted into the resonator, the resonant frequency was easily determined for all parts of the mouse, from the head to the lower abdomen. 3D EPR images of the mouse body from the thoracic region to the lower abdomen were obtained following infusion of a nitroxide, 3-carboxy-2,2,5,5-tetramethylpyrrolidine-1-oxyl (CxP). The EPR images clearly visualized the CxP distribution in various organs at different concentrations. Time-dependent EPR images also revealed that the signal intensities of the CxP decayed over time, and the decay rates for the heart, liver, and kidneys were evaluated.
A compact and mobile EPR imager that enables 3D whole-body EPR image of nitroxide in mice was developed. The EPR imager exhibited long-term stability against motion effects caused by respiratory motion and heartbeats in mice. The EPR images clearly visualized the in vivo distribution, clearance, and metabolism of the nitroxide in organs.
氧化还原稳态在调节生物体的整体健康和发育中起着关键作用。本研究旨在开发一种紧凑且可移动的连续波（CW）电子顺磁共振（EPR）成像仪，以促进对注入氮氧化物的小鼠进行稳定、高灵敏度的快速三维（3D）全身成像。
设计了一种直径为30毫米、长度为35毫米的多匝环形间隙谐振器用于全身EPR成像。使用该谐振器开发了一种工作在750兆赫的紧凑且可移动的CW-EPR成像仪。还调整了自动匹配和调谐控制系统，以补偿小鼠移动引起的扰动。
当将小鼠插入谐振器时，从小鼠头部到下腹部的所有部位都能轻松确定共振频率。在注入氮氧化物3-羧基-2,2,5,5-四甲基吡咯烷-1-氧基（CxP）后，获得了小鼠从胸部到下腹部的3D EPR图像。EPR图像清晰地显示了不同浓度下CxP在各个器官中的分布。随时间变化的EPR图像还显示，CxP的信号强度随时间衰减，并评估了心脏、肝脏和肾脏的衰减率。
开发了一种紧凑且可移动的EPR成像仪，能够对小鼠体内的氮氧化物进行3D全身EPR成像。该EPR成像仪对小鼠呼吸运动和心跳引起的运动效应具有长期稳定性。EPR图像清晰地显示了氮氧化物在器官中的体内分布、清除和代谢情况。
