Choose Top of page << Materials and Methods General Comments Windshield Glass Bottle Glass Wooden Toothpick Pencil Fragment Sewing Needle Galvanized Steel BB Shot Pellet Stone Plastic Conclusion References CITING ARTICLES The identification of soft-tissue foreign bodies is not always a straightforward pursuit. Although routine radiography is the preferred imaging modality for the initial workup, several types of soft-tissue foreign bodies are not radiopaque and therefore remain undetected. Because a retained foreign body may cause infection and inflammation, detection and removal are imperative [1]. Sonography is playing an increasing role in the diagnostic process, not only for the detection of non-opaque foreign bodies but also for the accurate localization of all types of soft-tissue foreign bodies. Accurate localization can be valuable in minimizing surgical exploration, or, alternatively, real-time sonographic visualization can guide percutaneous removal of a soft-tissue foreign body [2]. Sonography can also be used to evaluate associated soft-tissue abscess, neurovascular abnormality, and tendon disorders. This pictorial essay will define the imaging characteristics of various soft-tissue foreign bodies, comparing their appearances on sonography and radiography. Familiarity with the imaging appearances of soft-tissue foreign bodies is critical for an accurate diagnosis.

Materials and Methods Choose Top of page Materials and Methods << General Comments Windshield Glass Bottle Glass Wooden Toothpick Pencil Fragment Sewing Needle Galvanized Steel BB Shot Pellet Stone Plastic Conclusion References CITING ARTICLES Foreign bodies of various sizes, shapes, and compositions were placed in the heel pad of freshly thawed cadaveric specimens. A 5-mm plantar incision was made with a scalpel and the foreign body was manually inserted through the incision. The foreign body was placed at a random depth and orientation. The feet underwent radiography, and then sonography (Model 5200; Acoustic Imaging, Phoenix, AZ) was performed using a 7-10—MHz linear transducer without a standoff pad.

General Comments Choose Top of page Materials and Methods General Comments << Windshield Glass Bottle Glass Wooden Toothpick Pencil Fragment Sewing Needle Galvanized Steel BB Shot Pellet Stone Plastic Conclusion References CITING ARTICLES All soft-tissue foreign bodies are initially hyperechoic on sonography [1]. However, wooden foreign bodies may become less echogenic over time [1]. The conspicuity of soft-tissue foreign bodies on sonography is increased by a surrounding hypoechoic halo of granulation tissue, edema, or hemorrhage [1, 3]. This in vivo response was not present in the cadaveric specimens used in this study. Glass does not have to contain lead to be radiopaque—all glass material is radiopaque to some degree on radiographs [4]. The higher density and the effective atomic number of glass compared with the surrounding soft tissue are the factors responsible for its radiographic appearance [4]. Common glass products such as a drinking glass, a light bulb, and the two types of glass used in our study (the windshield and bottle glasses) contain no lead and yet are radiopaque [4]. Sonographic artifacts from soft-tissue foreign bodies aid in their identification. Such artifacts are seen deep in relation to the foreign bodies on sonography and are not related to the composition of the material; the surface characteristics of the object influence the type of artifacts produced, particularly “clean” versus “dirty” shadowing [5]. Objects with a small radius of curvature or a rough surface (i.e., a wooden toothpick and pencil) resulted in clean shadowing [5]. Objects with a large radius of curvature or smooth surface (i.e., glass and metal) result in dirty shadowing and reverberation artifacts [5, 6].