Acoustic Densitometry And Its Relationship With Renal Function In Chronic Renal Failure

Two-dimensional echo has a high sensibitity and specificity in diagnosing limited renal leisions , but is not so exact in diffuse disease. Intergrated backscatter is a newly developed technology to detect acoustic denisitometry, whose function is analyzing tissue character quantitively by obtaining tissue radio－frequence. It can detect backscattered signals of those small particles, which contain much information derived from tiny structure whose diameter is much less than the wave-length, and its aim is to help investigators quantify the brightness (intensity) of ultrasonic image. Objective: To study the variation of renal cortex's and medulla's IBS between contrasts and patients with chronic renal disease, explore the regularity in different ages and different renal function stages. Expect to build a foundation for studying diseases of renal parenchyma. Method: Three groups were analyzed, the first group was composed of patients with chronic renal failure, the second group comprised patients whose renal function were normal but biopsy results were abnormal ,and the third group included healthy subjects acting as controls. AD technology was performed to measure the normalized value of IBS(IBS%) of bilateral renal cortex and medulla of different groups. Analyze its relationship with renal function by comparing the IBS% of the three groups of different ages. Result: (1) Among contrasts , cortex and medullar IBS% in <40-year-old group was significantly lower in comparison with both 40-59 and ≥60-year-old. But no statistical difference was found between 40-59 and ≥60. The result is the same with groups of chronic renal diseases. (2) In group <40, normal renal function stage with abnormal bioposy(abbreviate as normal renal function), compensation stage, azotemia stage, uremia stage were comprised with contrasts. The result showed that cortex and medullar IBS% of four stages were significantly higher than those of contrasts. Compared with normal renal function and uremia stage groups, the IBS% of compensation group was higher than the former and lower than the latter, and both had statistics significance. IBS% weren't differentiated between other groups. (3) In group of 40－59, IBS% of cortex and medulla of patients in azotemia and uremia stage groups were significant higher than those of contrast group. When compare cortex IBS% and medulla IBS% of patients in uremia stage group with those in group with normal renal function, compensation, and azotemia stage , we found the first was significantly higher than all the others. (4) In group ≥60 years old, cortex IBS% of group with normal renal function, compensation, azotemia and uremia stage showed a significant increase than that of contrasts. The medullar IBS% of uremia stage was significantly higher than the contrasts'. When compare the IBS% of cortex and medullar, the group with normal renal function was significantly lower than the group in compensation stage.Discussion: When renal function is in compensation stage, the 2DE image of both kidneys may be normal, or only show reinforcement in cortex or weakness in parenchyma. During the end stage, both kidneys were contracted, the echo of renal cortex was strengthened, and the delimitation between cortex and medullar became unclear. For this reason, although two-dimensional echo has a high sensibitity and specificity in diagnosing limited leisions, it was less sensitive and specific in diffuse diseases. IBS is a new technology for analyzing tissue character quantitatively by obtaining the radio-frequency of corresponding regions.According to our study, we can conclude that: (1) When aged, the size, location and blood distribution of glomerulus will change correspondingly, and the collagen content in parenchyma will be added. As a result, the IBS% of renal cortex would increased. In medullar, many changes will also be taken place, such as changing in the length and volume of renal tubules, even a complete segment of one renal tubule will became atropy or disappeared. Mean...