FIGURE 131.33 Cobblestoning in soft tissue Foreign-Body Identification and Removal Ultrasound can be used for detection of radiolucent foreign bodies and accurate real-time two-dimensional localization of all soft tissue foreign bodies Real-time sonographic visualization can guide percutaneous removal of a soft tissue foreign body, minimizing surgical exploration Technique The technique used for subcutaneous foreign body identification is similar to evaluation for soft tissue infection A high-frequency linear transducer is preferred and the object should be identified in two planes If an object is very superficial, a water bath or a “stand-off pad” can be used to elevate the transducer off of the area of interest, improving resolution All soft tissue foreign bodies are initially hyperechoic on sonography The depth and size of the foreign body should be measured and any relationship to surrounding nerves and vessels should be noted Surrounding granulation tissue, edema, or hemorrhage can appear as a hypoechoic halo increasing visibility of the object Typically objects that are small or irregular, such as toothpicks or pencil tips, create clean shadows, while objects with large smooth surface, such as glass or metal, create reverberation artifacts such as comet tails To remove a foreign body using realtime ultrasound guidance, the transducer should be placed so that the center