An ultrasound imaging system (1) comprises an ultrasound transducer array (100) comprising a plurality of ultrasound transducer tiles (101a-d), each of said tiles having an independently adjustable orientation such as to conform an ultrasound transmitting surface to a region of a body (50) including a foreign object such as a pacemaker, a stent, or an interventional tool (200). Using a known spatial arrangement of a plurality of features (201-204) of the foreign object (200), the respective ultrasound images generated by the ultrasound transducer tiles are registered in order to generate a composite image, in which the position and orientation of the foreign object in the individual images is superimposed. The position and orientation of an interventional tool may be determined for each image using object recognition algorithms or using acoustic feedback information provided by at least three ultrasound sensors (201-204) arranged in a known spatial arrangement on the interventional tool.