DEVELOPMENT OF ULTRASOUND KIDNEY TRANSPLANT GLOMERULOGRAPHY

Purpose: The purpose of this study is to establish kidney transplant glomerulography using ultrasound enhancing agents and to evaluate the glomerular hemodynamics changes in various abnormal conditions in the graft using this method.

Methods and Materials: After intravenous bolus injection of US enhancing agents Levovist(TM),the intensity of ultrasound signals obtained from microbubbles in the graft subcapsular ROI (2mm by 20mm oval) including the amounts of glomeruli were counted sequentially by Advance Dynamic Flow (ADF; wide-band Doppler technique). Thus, time intensity curve (TIC) of the signals and it's several parameters such as T max, T 1/2, delta T and I max were obtained. Ultrasound glomerulogram will be representative of the hemodynamics in the transplant glomeruli themselves. Twenty-five kidney transplant recipients whose serum creatinine values ranged between 0.7~4.1mg/dl were examined. TIC parameters were compared to immunnosuppresive agent carcineurin inhibitor (CNI) trough levels. Changes of TIC before and after the administration of various AT1 receptor blockars (ARB) were also obserbed in 6 patients.

Results: T max and s-Cr values were correlated significantly (P=0.0003) in 9 patients with low CNI trough levels (CYA below 70 ng/ml, TAC below 7 ng/ml), whereas no correlations were seen in 12 patients with high CNI levels (P=0.0509, n.s.). These findings might demonstrate that various degrees of afferent arteriole constriction will occur in high CNI groups and glomerular blood flow was not correlated with s-Cr value consequently. T max and T 1/2 in all the 6 patients decreased significantly after administration of ARB Candesartan. This will become the evidence of the afferent and efferent arteriole dilating effects, glomerular tension lowering effect and partly renal protection effect of ARB.

Conclusions: Ultrasound glomerulography may be a noninvasive and sensitive tool to evaluate glomerular hemodynamics for analyzing CNI nephrptoxicity and a mechanism for evaluating the effect of vasoactive agents including ARB.