[Role of directional power-Doppler in the identification of renovascular malformations].

Objective: The directional power-Doppler (dPD) is a useful tool in evaluating the renal vascularization for its high sensibility and availability. Renal vascular malformations like the arteriovenous fistulas (avF) are rare and their real incidence is unknown. We evaluated the diagnostic role of dpD in renal avF.

Material And Methods: From January 1999 to 2002 1518 subjects (875 males, 643 females, mean age: 62 years, range: 22-87 years) have been studied by both B-mode ultrasound and by dpD. All ultrasonographies were taken with a Toshiba Power Vision 6000 by the same skilled operator.

Results: Among 1518 patients examined, 17 avF have been identified (diameter range: 3-18 mm) by using dPD. Four of these have an unclear etiology (congenital?) and they have been considered idiopathic. On the contrary, five are acquired: two are caused by renal biopsy, two by renal tumors and one by ureteral stent positioning, respectively. Eight patients, all affected by polycystic kidney disease, showed multiple avF. The four subjects with idiopathic avF are suffering from chronic renal failure (CRF--CrCl = 8-35 ml/min); on the contrary, among patients with polycystic kidney, five of them are on CRF (CrCl = 14-27 ml/min), three have normal renal function. The acquired avF caused by renal biopsy or by ureteral catheterization have spontaneously disappeared after 15-20 days from the causative event.

Conclusions: The dPD allows to individualize the arteriovenous malformations of renal vasculature which could be underestimated or not evidenced by other instrumental methods.