| Background:Renal neoplasm is common in urology. The survival rate and prognosis highly depend on early diagnosis and surgical resection. Most renal neoplasm are asymptomatic in early stage and can only be found by imaging techniques. The traditional methods for renal screening examination are fluoroscopy and routine ultrasonography, but this had some limitations in detecting small tumors. With the development of medical imaging modalities, color Doppler ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) had been used to diagnose renal neoplasm. Because of poor imaging contrast between normal renal tissues and tumor, artificial contrast medium was introduced to increase contrast between them, and this could gain higher sensitivity in diagnosis. Although contrast media is widely used in CT and MRI imaging, it was rarely applied in ultrasound examination for lack of ultrasound contrast agent (UCA). There are a few laboratories where different UCA are made and most are in experimental period. Domestic UCA are needed to further evaluate the imaging capability and imaging principle.Objective:This study was designed to evaluate the imaging capability and mechanism of a new lipid ultrasound contrast agent in comparison with contrast-enhanced CT and pathology, and it was also dedicated to assess the biological safety of UCA under 10 min, MI 0.28 exposure to ultrasound radiation followed by bolus injection. Methods:36 health rabbits were used in this study, and VX2 carcinoma was successfully transplanted in 26 kidneys. Successful transplantation was done in three kinds of methods. First, VX2 carcinoma was cut into tiny pieces in saline to make suspension of tumor tissues and the suspension was then injected into renal cortex guided by ultrasound. Second, rabbits were operated and VX2 carcinoma was implanted into kidney. The last, kidneys were exposed under surgery and the suspension was injected into renal cortex.14 rabbits with VX2 carcinoma of left kidney were scanned by fundamental imaging and second harmonic imaging (SHI) after injection of a new ultrasound contrast agent (Zhifuxian 0.02ml/kg), and followed by enhanced helical CT (HCT) scan and pathology examination. The number and distribution of VX2 lesions and the smallest lesion of every rabbit were photographed. Then the US, CT and pathological sensitivities were further analyzed by paired t test. The major VX2 tumor in 14 left kidneys were found involved, before the injection of the contrast agent the maximum imaging acquired with the low Mechanic Index (MI) diagnosis ultrasound, then the imaging was stabled after the injection of the liposome contrast agent, The first 10 mins contrast images were recorded and the time-intensities curve were generated from the contrast images, the time-intensities of the helical CT were also calculated from CT images within 24hs.In order to explore the vascular density within renal cortex and VX2 tumor tissues, ink dye was injected into abdominal aorta to stain the renal vasculature and quantification. Gray-scale value and acoustic densitometry were used to evaluate the perfusion of renal cortex and VX2 tumor. There was significant correlation between peak intensity of time-intensity curve and vascular density of renal cortex and VX2 carcinoma.Cultured renal tubular epithelial cells were divided into 4 groups: the first group was mixed with UCA without exposure to ultrasound, the second group was exposed to ultrasound at MI 1.5 without UCA, and the third group was exposed to ultrasound with UCA, MI 0.28. the fourth was exposed to ultrasound with UCA, MI1.5. Then the micro renal structures were observed under electron microscope. 5 rabbits with renal tumor were exposed to ultrasound for 10 min after injection of UCA, and the renal structure were observed under electron microscope and light microscope. Results:1. Animal models of renal VX2 carcinoma were successfully established using the three above methods.2. In all 51 gross lesions, contras...
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