The Study Of Renal Perfusion In Rabbits With Real Time Gray-scale Ultrasound Contrast Imaging

Objectives:To explore the feasibility of quantitative evaluation of renal perfusion by using real time gray-scale ultrasound contrast imaging and Wash-in/Wash-out time intensity curve.Methods:The examination of the renal contrast tuned imaging(CnTi)gray scale ultrasound was performed in 12 rabbits(24 kidneys)after intravenous injection of SonoVue.Then,two incremental doses of dopamine(DA)(2μg/kg/min,5μg/kg/min)were infused intravenously by microinfusion pump.After every dose of DA was infused for 10min,the examination of the left renal contrast imaging was performed.24h later,noradrenaline(NE) (0.3μg/kg/min)was infused.After NE was infused for 20min,the examination of the left renal contrast imaging was performed.Dydamic images was recorded in the hard disc of the instrument. Wash-in/Wash-out time intensity curve software was used to estimate the following parameters:time to enhancement,time to peak intensity,peak signal intensity,ascending slope rate of the curve and area under the curve.The renal perfusion was evaluated with these parameters which were obtained before and after intravenous infusion of NE or different dose of DA.Results:(1)The perfusion mode of the normal kidney:after a bolus injection of ultrasound contrast agent for 5-8s,the kidney started to enhance.The renal segmental artery,interlobar artery, cortex,,medulla and sinus were enhanced by turns.The renal medulla and sinus were enhanced slower than the renal corex.And the renal sinus,medulla and corex washed out by turns.(2) Quantitative parameters in the cortex or medulla of bilateral kidneys were not obviously different from each other respectively.But in the same kidneys,the time to enhancement and time to peak intensity were earlier in the renal cortex than in the renal medulla.The peak signal intensity was higher,the ascending slope rate of the curve was increased,and area under the curve was larger in the renal cortex than in the renal medulla.(3)After two incremental doses of DA infused intravenously,a dose-depend decrease in the time to enhancement and time to peak intensity were showed in the renal cortex or medulla.And a dose-depend increase in the ascending slope rate of the curve and area under the curve were showed in the renal cortex or medulla.But the peak signal intensity was not obviously different in the renal cortex or medulla.(4)After NE infused intravenously,the time to enhancement and time to peak intensity were delayed in the renal cortex.And the peak signal intensity,ascending slope rate of the curve and area under the curve were decreased in the renal cortex.But in the renal medulla,only was the time to enhancement delayed.The other quantitative parameters were not obviously different. Conclusions::Real time gray-scale ultrasound contrast imaging could show the character of the renal perfusion clearly.And it could observe the dynamic process of the renal perfusion.Corresponding parameters of the time-intensity curve could show the character of the nomal renal haemodynamics and detect the change of renal perfusion.