The Experimental Study Of Renal Blood Perfusion In Normal And ARF Rabbits By Intravenous Contrast Ultrasound And Relative Techniques

Background:Up to now, the diagnosis of ARF by ultrasound usually depends on the changes of kidney's morphology and gray scale intensity appearing in its two dimensional ultrasonography while there is no more effective approaches to assess the renal blood perfusion except to measure the velocity and resistance index of renal artery. In the past few years, the research of novel echo contrast agent and relative ultrasonographic techniques has made so great progress that people can more effectively and directly evaluate the blood perfusion of the tissues and organs than before. In this study, we are going to explore the feasibility of quantitative evaluation of renal blood perfusion in the normal and ARF rabbits by AD and PDI techniques on the basis of the self-made albumin perfluorocarbon ultrasonic contrast agent.Objective:1.To evaluate the renal parenchyma blood perfusion in normal rabbits by intravenous contrast ultrasound (ICU), acoustic densitometry (AD) and power Doppler imaging (PDI) techniques.2.To quantitatively assess the renal cortex blood perfusion of acute renal failure (ARF) in rabbits by ICU, AD and PDI.3.To study the relationship between the levels of serum creatinine (SCr), blood urea nitrogen (BUN) and the change of blood perfusion of renal cortex in ARF.4.To analyze the relationship between the change of blood perfusion of renalcortex in ARF and the pathological changes of kidneys.Methods:The renal images of normal rabbits were acquired before and at the time points of 5th to 95th seconds of all together eleven points after injecting self-made albumin perfluorocarbon ultrasonic contrast agent. The images were then assessed and contrastively analyzed, parameters such as peak intensity (PI), the area under the curve (AUC) and the mean transit time (MTT) of the renal parenchyma were measured before and after ICU according which the time-intensity curve was drawn. The animal model of ARF was established in rabbits by intramuscular injection of 50% glycerol (12~15ml/kg) into the hind leg. Rabbits' kidneys were examined by ICU,AD and PDI under ultrasonography on the day before glycerol injection(T0) and 1st,2nd,3rd,5th…11th,13th(T1,T2,T3,T5…T11,T13) day after glycerol injection. B mode and PDI images of the kidneys before and after echo contrast were observed, and there after being classified into three grades according to its intensity. Grade 1 was defined as the intensity of renal cortex in normal rabbit; grade 2 was defined as the intensity between the normal renal cortex and renal sinus; grade 3 was defined as the highest intensity as the renal sinus. The PDI images were also classified into three grades under the conditions of blood flow. GradeⅠwas as the blood flow signals could reach the renal cortex right under the integument; gradeⅡwas as the blood flow signals could be seen in renal cortex but far from the integument; grade Ⅲ was as the blood flow signals could not be seen in the renal cortex. Parameters as PI and AUC of the renal cortex were measured at each time point while the SCr and BUN were measured at the same time. At least 1 rabbit was killed at each time point and its kidney was sampled for pathological examination. The correlation between blood perfusion of renal cortex and the levels of SCr, BUN and the results of pathological examination was studied.Results:1. After intravenous injection of self-made ultrasound contrast agent, B mode and power Doppler images of the normal kidneys were greatly enhanced; PI and AUC of renal cortex increased obviously and lasted about 40 seconds. But the significant difference were not observed in MTT of renal cortex and in all of the parameters of renal medulla.2. The images of normal kidneys were obviously enhanced after intravenous echo contrast administration than those of ARF kidneys. The gray scale and PDI of normal and ARF kidneys appeared as grade 1 and Ⅲ respectively. After injecting ultrasonic contrast agent, the images of gray scale and PDI of most normal kidneys appeared as grade...