Best Duplex-Sonographic Criteria for the Assessment of Renal Artery Stenosis - Correlation with Intra- Arterial Pressure Gradient - Staub, D; Canevascini, R; Huegli, R W; Aschwanden, M; Thalhammer, C; Imfeld, S; Singer, E; Jacob, A L; Jaeger, K A (Ultraschall in der Medizin - European Journal of Ultrasound, 2007)