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

用H-1MRI分析大鼠脑间质间质中的体液流量。将几种松弛试剂(锰离子、Gd-DTPA、聚赖氨酸-DTPA-Gd、NMS-60)按1-3ul的体积注入脑内。通过T1加权MRI成像，可以检测到水对流引起的再松弛试剂的移动，间隔1分钟。在成年大鼠大脑中，当松弛试剂应用于大脑皮层的额侧时，试剂向鼻腔方向移动。另一方面，当试剂涂抹在点菜的尾部时，试剂向尾部方向移动。为了最大限度地减少松弛试剂注入的影响，我们尝试了一种最小注入的方法，但在MRI测量中，所有的金属设备，如泵，都必须与超导磁体保持距离。因此，注入的管路变得1米长。因此，我们不能获得良好的重复性的最小体积注射。我们将继续改进注射方法。我们还在7T高场MRI上建立了小鼠的活体成像系统，该系统能够测量大鼠的新生和幼年。初步结果表明，幼鼠(第4天)的血脑屏障可能比成年大鼠的血脑屏障更容易渗漏。

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.