Analysis of bulk flow in the ceiebral interstitial space measured by H-1 MRI

采用H-1 MRI对大鼠脑间质梁的大流量进行了分析。脑内注射松弛剂Mn离子、Gd-DTPA、聚赖氨酸- dtpa - gd、NMS-60，体积1- 3ul。t1加权MRI成像间隔1 min，可检测到水对流作用下松弛剂的运动。在成年大鼠大脑中，当将松弛剂施加于皮层额侧时，松弛剂向鼻腔方向移动。另一方面，当试剂应用在卡片的尾部时，试剂向尾部方向移动。为了尽量减少注射松弛剂的影响，我们尝试了最小注射量小于1ul；在核磁共振成像测量中，所有的金属设备，如泵，都必须与超导磁体保持一定的距离。因此，注入油管的长度为1米。因此，我们不能得到很好的重现性的小体积注射。我们将不断改进注射方法。我们还在7t高场MRI中建立了小鼠体内成像系统，该系统能够对新生大鼠和幼鼠进行测量。初步结果表明，婴儿（第4天）血脑屏障可能比成年大鼠漏血。

Bulk flow of water in the interstitial spars of brain of the rat was analyzed by using H-1 MRI. Several relaxation reagents (Mn ion, Gd-DTPA, polylysine-DTPA-Gd, NMS-60) were injected in the brain with 1-3 uL of volume. Movements of realaxation reagents by the convection of water can be detected by T1-weighted MRI imaging with 1-min interval. In the adult rat brain, when relaxation reagent applied in the frontal side of the cortex, the reagent moved to the nasal direction. On the other hand, when the reagent apply in the tail side of the carte, the reagent moved to the tail direction. In order to minimize the effects of injection of relaxation reagents, we have tried a minimal injection less tah 1 uL However; in the MRI measurements, all metalic apparatus, such as pump, have to take distance from the super conducting magnet. Therefore, the tubing line of the injection become 1 meter in length. Thus, we could not get good reproducibility of the minimal volume injection. We will keep to improve injection method. We also established in vivo imaging system for mice in the 7 T high-field MRI This system is capable to measure newborn and infants of rats. Preliminary results suggest that BBB in the rats infants (day 4) might be leaky than that of adult.