Molecular magnetic resonance imaging studies on ESR・MRI dual system

为了在生物和生物医学领域进行分子成像研究，发展了电子自旋共振(ESR)/磁共振成像(MRI)双成像系统。该系统是利用永磁体(Nb-Fe-B材料)构建的ESR/MRI双成像系统。双成像系统的ESR和MRI部分分别在1.2 GHz(0.04特斯拉)和22 MHz(0.5特斯拉)下运行。为了获得较大线宽的ESR成像的较高空间分辨率，采用了2mTesla/cm的磁场梯度。我们还利用多线圈平行间隙谐振器技术开发了ESR和MRI共振器，用于ESR和MR图像的联合配准。我们在我们开发的ESR/RI双重成像系统上开展了两个项目。项目一：利用顺磁性锰离子可视化和表征啮齿动物大脑中的钙内流。在本项目中，我们阐明了当神经元被激活时，NMDA受体在钙内流中起着重要作用。项目2：利用ESR/MRI双重系统测量氧化应激下脑组织的氧合。我们已经成功地用ESR/MRI双系统和氧敏探头在体内较长时间监测了P02水平的变化。该系统使我们能够同时测量PO_2和NO的生成。

For molecular imaging studies in the fields of biological and biomedical sciences, electron spin resonance (ESR)/magnetic resonance imaging (MRI) dual-imaging system was developed. This system, ESR/MRI dual-imaging system, was constructed using the permanent magnet (Nb-Fe-B material). The ESR and MRI part of the dual-imaging system was operated at 1.2 GHz (0.04 Tesla) and 22 MHz (0.5 Tesla), respectively. In order to obtain higher spatial resolution for ESR imaging of relatively-large line width, 2 mTesla/cm magnetic field gradient was used. We also developed ESR and MRI resonator for co-registration of ESR and MR images by using multi-coil parallel-gap resonator technique.We carried out two projects on our developed ESR/RI dual-imaging system.Project 1 : visualization and characterization of calcium influx in the rodent brain using paramagnetic manganese ions. In this project, we clarified that NMDA receptors play an important role for calcium influx when the neurons were activated.Project 2 : Measurement of brain tissue oxygenation under oxidative stress by ESR/MRI dual system. We have successfully monitored the change in p02 levels in vivo by ESR/MRI dual system with oxygen-sensing probe for relatively long terms. This system allowed us to measure pO_2 and nitric oxide generation simultaneously.