| BackgroundUltrasonic imaging of the kidney has proven useful in detecting hydronephrosis, renal cysts, and many solid renal tumors. Although findings such as increased echogenicity, loss of the cortico-medullary junction, and cortical thinning have been reported in diffuse renal disease, ultrasound has proven more useful as a guiding method for percutaneous biopsy than as a tool for direct diagnosis of diffuse renal disease. Percutaneous renal biopsy has long been the main method used for initial diagnosis of diffuse renal disease, this procedure also is frequently used to monitor disease progression. The major disadvantages of renal biopsy are the risk of renal hemorrhage, the small sample of kidney tissue obtained, and the high cost of the procedure. A noninvasive means evaluating structural changes in the renal cortex is, therefore, of great potential value.On-line analysis of integrated backscatter (IBS) is a new technique of ultrasonic tissue characterization. Transducer frequency, depth and gain are influences on IBS, thus the IBS value should be standardized to make it more comparable. The IBS values of renal parenchyma and sinus were measured, and the ratio was defined as the revised IBS of renal parenchyma. This standardized value has been used in recent years. Renal parenchyma/sinus IBS% among the CRF cases in azotemia stage and in uremia stage were significant different with normal controls, but there is no significance between those of CRF in normal function stage and normal controls.Renal parenchyma/sinus IBS% in normal persons increases with age. Therefore, renal parenchyma/sinus IBS% is not an ideal standardized value.ObjectiveTo compare renal cortex/spleen IBS% with Renal cortex/sinus IBS% in normal persons and explore clinical value of integrated backscatter on detecting chronic nephritis with renal failure in compensatory stage.MethodsUltrasonic backscatter data were acquired from the kidneys of patients with biopsy-proven chronic nephritis with renal failure in compensatory stage(27 patients plus 47 normal volunteers). The IBS values of spleen, renal cortex and sinus were measured. The renal cortex/sinus IBS% was defined as the revised IBS of renal cortex, and renal cortex/spleen IBS% was defined as a new standardized value of renal cortex. (For 20 native kidney patients in which renal biopsy slides were available, the size of glomeruli in representative sections were counted(the diameters of the glomeruli include Bowman's capsule). This was done by first selecting only those glomeruli that were sectioned centrally by identification of the afferent/efferent arteriole. Only patients having at least 5 centrally sectioned glomeruli were included in the analysis on the relationship between the diameters of the glomeruli and renal cortex/spleen IBS%). Operator characteristic curve(ROC)was used to determine the cutoff point of the renal cortex/spleen IBS% in diagnosing chronic nephritis with renal failure in compensatory stage.Results1. The IBS values of renal cortex and spleen , the renal cortex/sinus IBS% in normal persons increase with age. There was no significant difference in the IBS value of renal sinus and the renal cortex/spleen IBS% in different age groups. There was strong positive correlation between the IBS value of spleen and cortex in both kidneys.2. The renal cortex/spleen IBS% was statistically significantly different between the chronic nephritis group and normal control group in both kidneys. In normalpersons, the 95% confidence interval of the renal cortex/spleen IBS% was 55.7% - 102.8% in the left kidney and 59.2% ~ 112.3% in the right kidney. Using the renal cortex/spleen IBS% in left kidney with 88.5% as the cutoff value, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of diagnostic chronic nephritis was 64%, 70.2%, 69.0%, 55.2, and 78.6%, respectively. Using the renal cortex/spleen IBS% in right kidney with 93.1 % as the cutoff value, the sensitivity, specificity, accuracy, positive p... |
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