MR Guaided Focused Ultrasound Disrupting Blood Brain Barrier Of Rabbits With The Existence Of Microbubble

Objective1. To establish the skull window model.2. To construct process with MR TMap and signal intensity to monitor BBB disruption induced by ultrasound.3.To study dose-effect relationship of ultrasound and rabbits blood-brain barrier disruption with the existence of microbbuble .4.To study how BBB disruption lasted after sonication.5. To study the effection of microbbuble dosage upon BBB disruption.Methods1. It was made that skull window rabbit models with surgery , then rabbits were sonicated 7 to 30 days later .2. MR TMap was applied to monitor temperature change and peak temperature of sonicated area . MR scaning was applied to watch imageology change of sonicated area . MR enhanced intensity signal and Evans Blue quantitation test were applied to evaluate BBB disruption . With these process we studied①significance of MR TMap detecting rabbits BBB disruption deduced by focused ultrasound with the existence of microbbuble ,②MR signal intensity detecting rabbits BBB disruption deduced by focused ultrasound with the existence of microbbuble③the dose-effect relationship between BBB disruption and sonication time④effection of microbbuble dosage upon rabbits BBB disruption . Data was dealed with statistics software SPSS13.Results1. It was satisfied to sonicat 10—21days after skull window surgery .2. Peak temperature of contrast and microbbuble groups did not change with sonicating time , PT of ultrasound and microbbuble group and ultrasound group heightened with the increase of sonicating time, it was positive correlation between them .3. Signal intensity(SI) of contrast and microbbuble groups did not change with sonicating time .SI of ultrasound and microbbuble group and ultrasound group increased with the increase of sonicating time as it was less than 14 seconds , decreased with the increase of sonicating time as it was more than 14 seconds .4. Evans Blue contents in brain tissue of sonicatied area in contrast and microbbuble groups did not change with sonicating time . Evans Blue contents in ultrasound and microbbuble group and ultrasound group increased with the increase of sonicating time as it was less than 16 seconds , decreased with the increase of sonicating time as it was more than 16 seconds .5. Watched in light microscope,only micro changes were found in the sections which were sonicated 6—10S, hydropsia was found in the sections which were sonicated 12s and 14S, micro circle necrosis and haemorrhage were found in the sections which were sonicated with 16S ultrasound , serious necrosis was found in the sections which were sonicated 20S6. It was positive correlation between Evans Blue contents in brain tissue and Signal intensity of sonicatied area , R square was 0.872 .7. In 6W6S group , MR SI1 reached the peak at 2 hours after sonication and decreased from 4 hours after sonication , 8 hours after sonication it got to the same level as before sonication . In 6W16S group , MR signal intensity SI1 reached the peak at 2 hours after sonication and SI1 got a relative unchangeable level 4 hours after sonication .8. In 6W6S group , PT of each group increased with the increase of micrabbuble dosage ,MR signal intensity SI1 increased with the increase of micrabbuble dosage . In 6W10S group , PT of each group increased with the increase of micrabbuble dosage .SI1 increased as it was less than 0.05ml/kg, decreased as it was more than 0.05ml/kgConclution1. It was the best time to sonication 7—21days after windowing surgery .2. MR TMap and peak temperature could monitor tendency of tissue and temperature change .3. MR inhanced scan with injection of MR contrast could used to adjust BBB disruption and applied in clinical test .4. With certain dosage of microbbuble , ultrasound frequence and power , BBB disruption increased with increase of focused ultrasound sonicating time . 14S was the threshold of rabbits brain tissue necrosis .5. With certain sonication time ,ultrasound frequence and power , BBB disruption increased with increase of microbbuble dosage . 0.05ml/kg was the threshold of rabbits brain tissue necrosis .6. With certain dosage of microbbuble, ultrasound frequence and power , BBB disruption and disruption lasting phase were influenced by sonication time .7. Microbbuble could not ouly enhance BBB disruption deduced by focused ultrasound, but also lower applied ultrasound power . So as to decrease damage of brain tissue caused by ultrasound sonication.