Background: A renal biopsy represents the gold standard in the diagnosis, prognosis and management of patients with chronic kidney disease and glomerulonephritis. Strain wave elastography (SE) is a developing technique to assess tissue elasticity. The aim of this study was to correlate between the strain index value of renal parenchyma and degree of renal fibrosis detected with renal biopsy.
Method: For 68 patients who were referred for a kidney biopsy, SE test was performed. The Banff scoring system was utilized to classify the IFTA grading of kidney fibrosis that assigns a severity level of mild, moderate, or severe. Receiver operating characteristic curve (ROC) was utilized to correlate between the severity of renal fibrosis and the grade of renal elasticity determined by SE.
Results: In total, 38 males and 30 females, the echogenicity, qualitative and semiquantitative elastography showed significant positive correlation with serum creatinine, percentage of fibrosis, G score and tubular atrophy and significant negative correlation with eGFR. ROC curve of SE for diagnosis of interstitial fibrosis shown that echogenicity has sensitivity 100.0%, Specificity 62.5%, positive predictive value (PPV) 75.0%, negative predictive value (NPV) 100.0% with area under curve (AUC) 0.906, while qualitative elastography has sensitivity 77.8%, specificity 75.0%, PPV 77.8%, NPV 75.0% AUC 0.833, semi quantitative elastography has sensitivity 83.3%, specificity 93.8%, PPV 93.8%, NPV 83.3% with AUC 0.915.
Conclusion: SE approach is simple to use, and can differentiate between varying stages of renal fibrosis. However, further research is required before it can be frequently used in clinical practice.
