An imaging ultrasound system is provided with an ultrasound transducer and an image processing unit for the acquisition of a three-dimensional ultrasound image of the body of a patient, and a catheter for carrying out a therapeutic or diagnostic intervention in the body of the patient. The catheter accommodates, in addition to the customary instruments necessary to carry out its task, three ultrasound receivers that are mounted at a distance from one another on the tip of the catheter and are capable of detecting the arrival of scan signals of the ultrasound transducer. The distance between the ultrasound transducer and the receivers can be calculated from the transit time of the scan signals. The receivers can thus be localized in space. Localization enables notably the selection of, for example, the plane from the three-dimensional ultrasound data that contains all three receivers of the catheter. The tip of the catheter can thus be automatically tracked and displayed on a monitor at all times without manual displacement of the ultrasound transducer being necessary.