Experiment Parameters Study Of Low-freqence Focused Ultrasound Asssociated With Microbubble On Opening Rat's Blood Brain Barrier

Objective :With fixed ultrasonic frequency ,sound intensity and eaqul size, dose, concentration of microbubbles ,to investigate the time parameters of Low-Freqence focused ultrasound associated with microbubble distruption on opening blood brain barrier .Methods :Healthy Sprague Dawley adult rats were randomly divided into group A,B, C. Group C was divided into subgroup C1,C2,C3,C4 by different exposed time. After injecting microbubble and Evans blue by tail vein, the rat brains were sonicated by different exposed time with freqence of 1MHz and intensity of 4W/cm~2. Histopathologic studies was made to reveal the opening of blood brain barrier.Results :When the exposed time was 0.5 min, the brain histologic changes were not obvious.In groups of 1.0 min,1.5 min and 3.0 min, Evans blue dye exudation in the brain was observed and RBC exudation was observed in groups of 3.0 minutes by HE stained.Conclusions: Our experiments demonstrated the feasibility of Low-freqence focused ultrasound asssociated with microbubble disruption on opening the blood brain barrier reversively in the focal tissue with the ultrasound freqence of 1MHz , intensity of 4 W/cm~2 , microbubbles mean diameter of 1.5μm, concentration about 5x108/ml～8x 108/ml and exposed time ranging from 1.0 min to 1.5 min.