Microcavity-containing polymeric medical devices for enhanced ultrasonic echogenicity

Abstract

An ultrasound-detectable polymeric device that offers superior visibility of the body of the device and decreased ultrasound angle dependence through the use of microcavities and methods of manufacturing thereof is disclosed. These microcavities enable superior ultrasound visualization due to diffuse reflection of sound waves when compared to solid polymeric objects, ensuring that a strong signal is received at the source of the ultrasound transducer and providing strong image contrast throughout the entire cross-section of the implant that is also robust to variable angles of insonation.

We claim: 
     
         1 . An ultrasound-detectable medical device comprising a polymer with microcavities dispersed in some or all of its body capable of providing improved visibility throughout some or all of its volume and under variable angles of insonation. 
     
     
         2 . The ultrasound-detectable device of  claim 1 , wherein the diameter of the microcavities is about 0.1 to about 950 microns. 
     
     
         3 . The ultrasound-detectable device of  claim 1 , wherein the diameter of the microcavities is about 50 to about 350 microns. 
     
     
         4 . The ultrasound-detectable device of  claim 1 , wherein the volume to volume ratio of polymer structures to cavity space is than 60%. 
     
     
         5 . The ultrasound-detectable device of  claim 1 , wherein the volume to volume ratio of polymer structures to cavity space is about 12% to about 50%. 
     
     
         6 . The ultrasound-detectable device of  claim 1 , wherein the microcavities are formed by at least one gas. 
     
     
         7 . The ultrasound-detectable device of  claim 6 , wherein the at least one gas is selected from CO 2  or N 2 . 
     
     
         8 . The ultrasound-detectable device of  claim 1 , wherein the microcavities are created via a chemical reaction within the material such that gas is released. 
     
     
         9 . The ultrasound-detectable device of  claim 1 , wherein the part of the device where improved echogenicity is desired contains a microcavity-containing polymer and the remainder is composed of a non-microcavity containing polymer or non-polymer. 
     
     
         10 . The ultrasound-detectable device of  claim 1 , wherein the microcavities are encapsulated by an outer skin layer. 
     
     
         11 . The ultrasound-detectable device of  claim 1 , wherein the device is designed for use as an echogenic marker for ultrasound location in the human body. 
     
     
         12 . The ultrasound-detectable device of  claim 1 , wherein the material comprises one or more resorbable polymers selected from the group comprising poly(lactic-co-glycolic acid) (PLGA), polylactide (PLA), polyglycolide (PGA), polyhydroxyalkanoate (PHA), polycaprolactone (PCL) and copolymers thereof. 
     
     
         13 . The ultrasound-detectable device of  claim 1 , wherein the material comprises one or more non-resorbable polymers selected from the group comprising polycarbonate, polyetheretherketone, polypropylene, silicone or polyethylene. 
     
     
         14 . A method for preparing the ultrasound-detectable marker of  claim 1  comprising the steps of:
 a. foaming the polymer by introducing a blowing agent; and 
 b. injecting the foamed polymer into a mold to form said marker. 
 
     
     
         15 . A method for using a device of  claim 1  comprising:
 a. inserting the device of  claim 1  in a patient; 
 b. detecting the device using B-mode ultrasound during or after surgery; and 
 c. detecting the device in multiple frames, representing different angles of insonation, during or after surgery.