Renal Venous Doppler Ultrasonography in Normal Subjects and Patients with Diabetic Nephropathy: Value of Venous Impedance Index Measurements

Objectives: To provide reference values of intrarenal venous impedance index (VII) measured with duplex Doppler ultrasonography in a healthy adult population and to assess the usefulness this index for evaluating the functional status of kidney in patients with diabetic nephropathy (DN). Methods: Between May 2005 and December 2009, Doppler ultrasonography of both kidneys was performed in 164 healthy volunteers (controls) and 58 patients with DN. Renal interlobar and segmental vein Doppler waveforms and VII were obtained and compared between groups using the Student's t test. Correlation between VII and serum creatinine concentration (SCC) was calculated. Results: In controls, the mean VII was lower in interlobar than in segmental renal veins (p < 0.01), without difference between the right and left kidneys. Waveform modulation was dampened in DN patients whose mean VII (0.32 +/- 0.18) was lower than in controls (0.38 +/- 0.18) (p < 0.01). SCC showed moderate correlations (r = 0.65) with intrarenal VII in the patient group. Conclusions: Renal VII is typically lower in DN than in controls and moderately correlated with SCC, which reflects renal function in DN, but does not offer a significant advantage over arterial resistance index. (C) 2011 Wiley Periodicals, Inc. J Clin Ultra-sound 39:512-518, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jcu.20835