Figure 3. (a) Baseline unenhanced colour and spectral Doppler ultrasound examination of a patient right lower limb. Insufficient information for a firm conclusion about patency of the anterior tibial artery. (b) Following the administration of 2.4 ml of SonoVue, clear depiction of a patent anterior tibial artery is seen (long arrow) with a large collateral artery seen in a superior position (short arrow). (c) Spectral Doppler contrast ultrasound confirms a monophasic abnormal arterial trace. (d) Corresponding arteriogram confirms the patent anterior tibial artery (long arrow) and the collateral artery (short arrow). Collateral arteries have formed around an occluded popliteal artery. (Courtesy of Dr J Langholz).