[Color-Doppler of renovascular diseases]

The color-flow mapping (CD-PD) is a safe, repeatable and non invasive imaging technique that shows the vessels trip and simplifies the spectral wave detection wich is fundamental to perform a quantitative analysis of Doppler signal. In the last years, digital ultrasound technology has increased the sensitivity and accuracy of Doppler procedures and has also reduced technical pitfalls. The role of CD-PD in the diagnosis and follow-up of a great number of renal vascular diseases is very important. Particularly, it is a screening test of chronic ischemic nephropathy caused by stenosis of the main renal artery or by atherosclerotic remodelling of the intrarenal vascular tree. The Systolic and Diastolic velocity peak (SVP and DVP), as were as spectral broadening and reno-aortic ratio (RAR), are the most significant criteria for the diagnosis of renal artery stenosis. The bilateral evaluation of the resistance indices and of the early systolic peak, in order to highlight parvus-tardus sign, leads the clinical choice between stenting and conservative therapy. MRI and TC complete the diagnostic flow-chart and allow the clinician to define the treatment. Values of IR > 0.80 and IP > 1.50, without a clinical history of chronic nephropathy and main renal artery stenosis, must be considered as indicators of nephroangiosclerosis and/or atheroembolic disease. In other words, the increased impedance suggests a remodelling of the microcirculation with a reduction of the cross sectional area of vessels and an increase of the total peripheral resistance of the kidney.