Ultrasound is typically performed with the use of an external transcutaneous probe that emits ultrasonic energy and measures the timing of reflected waves, thus allowing measurement of fluid flow or formation of a two-dimensional image. Clinically, the modality is limited by attenuation of the signal with increasing depth of penetration of the ultrasound into tissues, as well as by similarities in echo-genicity between different tissues. The present invention includes a system in which an intravascular probe actively transmits ultrasound that can then be detected by in-line piezoelectric transducers without reflection. This signal can be overlaid onto traditional B-mode or Doppler representation. Furthermore, the present invention includes a signal processing system that will display a real-time graphical representation of the vascular anatomy in order to assist the surgeon or procedural radiologist in the placement of central venous catheters.
