Prediction of tubulo-interstitial injury by Doppler ultrasound in glomerular diseases: value of resistive and atrophic indices.

Background: Doppler ultrasound is increasingly used in Nephrology for diagnosis of renovascular hypertension and evaluation of allograft dysfunction. However, its utility in glomerular disease remains controversial.

Objectives: Using Doppler Ultrasound, we prospectively tested the role of resistive and atrophic indices in predicting tubulointerstitial lesions in patients with glomerular disease as demonstrated by renal biopsy.

Methods: Seventy one patients with primary or secondary glomerular diseases were examined by Doppler ultrasonography immediately before renalbiopsy. The resistive and atrophic indices (RI & AI) were calculated and compared with histologic changes in biopsy specimen.

Results: Receiver Operator Characteristics analysis showed RI of 0.60 as an optimal value for discriminating tubulointerstitial changes with sensitivity of 82.7% and specificity of 92%. An AI of 0.65 was shown to be optimal for discriminating tubulointerstitial injury with sensitivity of 69.2% and specificity of 85%. The combination of the two indices had not been found to be superior to either index alone. There was a significant correlation between atrophic and resistive indices. (r=0.358, p< 0.01). It was observed that older age, smoking, elevated AI and RI, low GFR, high serum cholesterol and Hypertension were found to be significantly associated with the presence of tubulointerstitial injury in the univariate analysis whereas only elevated AI and RI were found to predict tubulointerstitial injury in multivariate analysis.

Conclusion: Measurement of RI by Doppler ultrasound can be considered as a supplementary diagnostic tool in glomerular diseases to predict the severity of tubulointerstitial injury.