Ultrasound can be used for localizing soft tissue foreign bodies. Examinations should be performed with the highest frequency transducer applicable. The area of interest is often feet or hands. The size and the echogenicity of the foreign body is maybe the most important factors regarding detection. Superficial objects may be hard to detect, but using the linear array transducer and a stand-off pad to elevate the transducer can likely help in such situations. A foreign body is likely to appear hyperechoic where wood, glass, and plastic tends to produce shadowing while metal objects tend to produce reverberations, comet tail artifacts and acoustic shadowing.
Be aware that detection of a foreign body can be time consuming. Multiple attempts should be made to visualize the region of interest from as many angles possible. Keeping the probe parallel to the object makes visualization the easiest. To avoid foreshortening the appearance of the foreign body care should be taken to find the true long axis of it. The foreign body surrounding tissue may present hypoechoic often indicating pus or granulation tissue. The degree of the associated inflammation can likely be visualized using color doppler showing vascular in-growth. When scanning for foreign bodies knowledge of regional anatomy is crucial. Distractions when scanning may include gas and proteinaceous of echogenic fluid, also be aware that bony, articular surfaces and scars may appear hyperechoic.
Disclaimer: The information herein is not intended to replace the product’s User Manual. Please consult the User Manual for comprehensive information and cautionary guidance about the product’s operation and use.