Fig. 3From: Ultrasound-guided cannulation of hemodialysis accessIdentification of the needle tip by dynamic scanning. By adjusting the probe perpendicular to the needle shaft, the echogenicity of the shaft (dotted line) markedly increases. With the forward movement of the probe, the ultrasound image changes as indicated (inset, A to C). Strictly speaking, the precise location of the needle tip is between B and C Back to article page