The invention relates to an interventional device (10) including a plurality of signal assemblies, a method of assembling such interventional device (10), an assembling system for such interventional device (10) and a corresponding software product. In order to provide a number of signal assemblies including, for example, ultrasound transducers (40) in an interventional device (10) with a reduced risk of thrombi formation or similar complications a desired flush and smooth surface of a casing (15) of the interventional device (10) is achieved if the signal assemblies are inserted in such a manner that they are urged into their respective positions from inside the casing (15) after such insertion.