Detection of foreign bodies in soft tissues: experimental comparison of ultrasonography and xeroradiography.

The value of xeroradiography and of high-resolution ultrasonography was compared on minute samples of foreign bodies of various radiographic density (wood, plastic, metallic wires and needles, glass, fish bones). The samples were introduced into pieces of veal meat at different angles with respect to the surface. Xeroradiographic images were taken at 60 kVp, with 32 mAs, and were developed in both positive and negative mode. The echographic examinations were performed using a real-time sector 10 MHz probe placed directly over the specimen, with constant gain rates. The results confirm the value of xeroradiography and demonstrate the effectiveness of high-resolution ultrasonography for the detection of minute foreign bodies. Some materials showed a peculiar echographic pattern, like sand, that corresponded to a frank acoustic shadow, or like metal and glass, showing a comet tail of reverberation artifacts. Wood and fish bones were well outlined, while plastic was less effectively represented. High-resolution ultrasonography is considered to be a first-line technique in searching for many kinds of minute foreign bodies, to be used in combination with xeroradiography in routine clinical examination.