| 摘要 |
An echogenic medical device such as a stent for insertion into a biological tissue or vessel comprising an elongate tube and having at least one lumen extending substantially along a longitudinal axis. The elongate tube compris es a material having an acoustic impedance different from the acoustic impedanc e of the biological tissue or vessel of a patient body such that ultrasonic imaging of the tube inside the patient~s body may be achieved. The elongate tube may comprise a plastic material such as polyethylene or any formable, pliable material which may be molded and/or extruded to a variety of shapes depending upon a specific application. The invention improves ultrasonic imaging by entrapping air in a lumen of the stent, which may have any cross- sectional shape and which may be sealed anywhere along the longitudinal axis . The stent may include curled ends for positioning the stent in a body vessel , a plurality of holes for draining fluid in a body tissue, and additional lum en to entrap air and to further enhance ultrasonic imaging of the stent. The coils of the curled ends may also be tightly spaced together to provide ultrasound reflection. In another aspect of the invention, a material such a s a foaming agent may be added during the extrusion process to cause the formation of CO2 gas to form in the material as it is being extruded. In yet another aspect of the invention, a mesh stent may be used to advantage eithe r by modifying the individual elements to be more echogenic or by adjusting th e braid configuration to be more reflective. |
