Using Image-based Dynamic Ultrasound Spectrography (IDUS®) technology, the intrabody monitoring and positioning of an inserted catheter is achieved by coupling a thin micron-size polymeric wire to the catheter with 100-500 micron metallic cylinder attached to the tip of the wire. The area of interest is imaged and subsequently stimulated using specialized stimulation schemes delivered by an imaging ultrasound transducer. The targeted metallic tip is stimulated and emanates a unique acoustic response (signature) corresponding to its mechanical and material properties. Because of the fundamental structural differences between the targeted metallic tip and its surroundings, its unique resonant frequency signature can be analyzed and differentiated relative to the surrounding soft tissue, the wire and the catheter itself so that the location of the catheter in the body can be determined.