DEVELOPMENT OF FUNCTIONAL OXYGENE METABOLIC IMAGING

为了建立一种磁共振成像（MRI）技术，用于激活灶氧代谢增高的标测，本研究进行了以下几方面的工作：1.毛细血管MR对比度的研究激活灶毛细血管红细胞压积明显增高。为了研究MR信号与毛细血管中红细胞数量和氧合变化之间的关系，通过用快速袖带充气机在几个袖带压力下压缩大腿来使小腿充血，并通过MRI和NIBS进行测量。大腿的闭塞使小腿缺氧，从而增加顺磁性脱氧血红蛋白。MR信号强度随压迫压力的增加先降低后恢复。这种现象是通过血管内外的磁化率差异来理解的。血管内磁化率随脱氧血红蛋白含量的增加先增加，血管外磁化率随脱氧血红蛋白含量的增加后增加。 关于我们 肌红蛋白的氧合2. MR对比度的澄清以反映RBC的数量和氧合毛细血管中RBC周围的磁场畸变反映了由于神经元激活而改变的组织氧合。为了阐明MR对比度和RBC饱和度之间的关系，我们详细研究了RBC周围的磁场畸变，发现血液T2^* 和T2在血氧为90%时最大。这种现象是基于红细胞和血浆的磁化率在血液氧合时相等。当加入顺磁性MR对比剂增加血浆的磁化率时，最大血T2^* 和T2的血氧降低。阐明了红细胞周围磁场畸变对MR信号的影响。3.氧代谢成像的发展为了对氧代谢进行成像，应关注通过毛细血管供氧的组织区域的MR对比度。毛细血管中红细胞的磁化率反映了组织氧浓度。红细胞周围的磁场畸变是沿着毛细血管移动的，并且当通过添加顺磁性MR造影剂增加血浆的磁化率时发生变化。特别地，在RBC和血浆的磁化率相等的情况下，RBC和血浆之间将不存在磁差，并且RBC周围的移动磁畸变消失，导致组织中的T2最大化。对毛细血管内红细胞周围磁场畸变敏感的磁共振脉冲序列正在研制中。少

To develop a magnetic resonance imaging (MRI) techtque for mapping of oxygen metabolism which increases in activation foci, this study was conducted as follows.1.Investigation of MR contrast in capillariesHematocrit increases obviously in capillaries of activation foci. To investigate the relation between MR signal and changes in RBC quantity and oxygenation in capillaries, a lower leg was congested by compressing a thigh at several cuff pressures with a rapid cuff inflator and was measured by MRI and NIBS. The occlusion of a thigh made a lower leg hypoxic so ass to increase paramagnetic deoxygenated hemoglobin. MR signal intensity first decreased, then resumed with an increase of compression pressure. This phenomenon is understood by the magnetic susceptibility difference between inside and outside blood vessels. The magnetic susceptibility inside blood vessels increased first with an increase of deoxygenated hemoglobin, then that outside blood vessels increased with an increase of de … More oxygenation of myoglobin.2.Clarification of MR contrast to reflect quantity and oxygenation of RBCsThe magnetic field distortion around RBCs in capillaries reflects tissue oxygenation which changes due to neuronal activation. To clarify the relation between MR contrast and RBC saturation, we investigated the magnetic field distortion around RBCs in detail and found that both blood T2^* and T2 is maximized at the blood oxygenation of 90%. This phenomenon is based on that the magnetic susceptibilities of RBC and plasma equalize at that blood oxygenation. When the magnetic susceptibility of plasma is increased by adding paramagnetic MR contrast agent, the blood oxygenation of maximum blood T2^* and T2 decreased. We clarified how the magnetic field distortion around RBC influences on MR signal.3.Development of oxygen metabolic imagingTo image oxygen metabolism, MR contrast of tissue area in which oxygen is supplied through capillaries should be concerned. The magnetic susceptibility of RBC in capillaries reflects tissue oxygen concentration. The magnetic field distortion around RBCs is moving along capillaries and changes when the magnetic susceptibility of the plasma is increased by adding paramagnetic MR contrast agent. In particular, where the magnetic susceptibilities of RBC and plasma equalize, there would be no magnetic difference between RBC and plasma and the moving magnetic distortion around RBC disappears, giving rise to maximize T2 in tissue. The MR pulse sequence which is sensitive to the magnetic field distortion around RBC in capillaries is under development. Less