Abstract: A medical diagnostic system, the system comprising: a) a non-ultrasound imaging module configured to generate a volumetric vascular map; b) a controller configured to translate a 3D position co-ordinate from the map into an aiming instruction; c) a Doppler ultrasound unit adapted to aim a transducer responsive to the aiming instruction; and d) a registration module configured to register a position of the transducer with respect to the volumetric map.