RESUMO
Objective To explore the rule of transportation in extracellular space (ECS) and the changes induced by the external stimulation with tracer-based MRI.Methods Thirty two mature Sprague Dawley rats were randomly divided into four groups,i.e.caudate nucleus-control (Cc) group,thalamus-control (Tc) group,caudate nucleus-moving (Cm) group and thalamus pain stimulation (Tp) group.The rats were anesthetized and a series of MR scanning were performed before and after the injection of Gd-DTPA in ECS of caudate nucleus and thalamus until the intensity of Gd-DTPA was invisible.Half-life of Gd-DTPA in ECS was calculated and analyzed with t-test.Results Gd DTPA in caudate nucleus was transported to the ipsilateral cortices away from the injection points,which only distributed on site in the thalamus.The transportation between the two partitions was not observed.The half-life of Tc group ([49.93±2.11] min) was significantly shorter than that of Cc group ([104.30±54.12];t=2.839,P＜0.05),no difference was observed between the Cm group ([113.42±47.32]min) and Cc group (t=0.359,P＞0.05),while half-life of Tp group ([109.40±10.33]min) was significantly longer than that of Tc group (t=15.954,P＜0.05).Conclusion Tracer-based MRI can be used to investigate the rule of transportation in ECS,and the transportation and clearance of substances into the ECS can be influenced by a selective external stimulation.