The sonographic appearance and contrast enhancement of puncture needles.

Investigations on the ultrasonic appearance of puncture needles in vitro and in vivo are reported. The images from the waterbath phantom correspond closely to those seen in the human body. The surfaces of smooth puncture needles reflect the ultrasonic beam so that, in most cases, the shaft is not visible. Surface roughnesses and small air bubbles enhance echogenicity and contrast of such needles. These roughnesses or inhomogeneities may be extraluminal or intraluminal. The phenomenon of the needle tip echo and its modifications are interpreted as physical and technical artifacts.