Abstract: The multilumen catheter (2) is provided at one end with a needle system (9, 9′) formed by two or more single-lumen needles which are provided with respective discharge openings (110, 111) and which, via their longitudinal lumina (10, 11), are connected to corresponding lumina (3, 4) of the catheter for separate release of a tracer fluid for external image diagnostics systems and therapeutic fluids, for example DNA plasmids. The needles may be both straight or both helical or one of these needles may be straight and the other needle may be helical.