Application Of Ultrasound Integrated Backscatter In Measurement Of Chronic Rejection Of Transplanted Kidney

In recent years, integrated backscatter(IBS) imaging technique has been proposed as a new method of ultrasonic tissue characterization. Integrating the radio frequency backscatter signal provides a potentially useful measurement for tissue characterization.Objective: To compare the IBS of renal cortex and medulla, and explore the clinical application of IBS quantifying transplanted kidney.Methods: All the people divided into 2 groups: healthy persons and patients, were analyzed with HP 5500 sonograph. Average image intensity(AII),peak to peak intensity(PPI) and standard deviation of image intensity(SDI) of renal were measured and normalized by IBS of renal sinus and expressed as IBS%,PPI% and SDI%.Results: (1) IBS% of renal cortex and medulla, PPI and SDI of renal medulla were both higher significantly in patients than those in control (p<0.05). PPI,SDI,PPI% and SDI% of renal cortex, PPI% and SDI% of renal medulla were higher in patients than those in control, but there were no significant difference. (2) With the aggravation of renal function, the value of [cortex– medulla IBS%] had a gradual decrease in patients. However, no significantdifference was found among all the people.Discussion: The components of renal parenchyma ,such as glomerulus,renal tubule and renal interstitium are just good scattering sourse. Renal integrated backscatter (IBS) a noninvasive parameter of the acoustic properties of renal parenchyma can reflect pathological changes in nephrosis.In healthy persons, IBS% of renal cortex and medulla increased gradually with aging. This indicates that influence of age on renal ultrasonic characters can not be neglected. Because with aging, renal will undergo serial retrogressive changes and eventually lead to the increase of IBS%. According to this, we choice all the people whose ages range from 30y to 60y to reduce selection bias and improve statistical significance.Many experimental studies have show that tubulointerstitial fibrosis can exactly forecast the aggravation of renal function, and it was more closely related to renal function and prognosis than glomerulus sclerosis. The pathologic change of tubulointerstitial can be directly used to estimate prognosis. The histological changes showed tubular atrophy and disappearance, widening of intertubular spaces with increased lymphocytes and mononuclear cells infiltration and fibrosis.In this study, with the aggravation of renal function, the value of [cortex– medulla IBS%] had a gradual decrease in transplantedkidney. Similarly, the histological change of renal medulla is greater than that of renal cortex.To examine transplanted kidney in patients, a significant difference can found between IBS decrease in parenchyma IBS and renal function severity. With the aggravation of renal function, in metaphase and advanced phase IBS% had a gradual increase. Especially in advanced phase, there were great significantly increase in IBS. The fundamental cause of the change of IBS lies in pathologic change, which result in the changed of microstructure, and consequently, in scattering sourses'number,size and array ect. In early phase during the impairment of renal function, glomerulus and tubulointerstitial mainly presents inflammatory, thus IBS of renal cortex increases. While in metaphase and advanced phase, tubular atrophy and disappearance, widening of interstitial spaces with increased extracellular matrix and fibrosis seem to be the key features of this final common pathway, so IBS of renal medulla increases.This study had been shown for the first time in transplanted kidney detection in IBS imaging technique. At the same time, it had quantitatively evaluated the echo change of increased renal cortex and unclear borderline between renal cortex and renal medulla in two-dimensional echo feature. Combination of IBS technique and 2DE can achieve qualitative and quantitativediagnosis in terms of ultrasonography, with important potential implication for research and clinic.Conclusions: (1) With the application of IBS technique, pathologic change of renal can be evaluated qualitatively and quantitatively. (2) IBS can reflect the echo change of renal. (3) The demonstration of renal IBS index and the possibility of its noninvasive evaluation in human beings has potential in test and clinical implications.