Visibility of different foreign bodies in the maxillofacial region using plain radiography, CT, MRI and ultrasonography: an in vitro study

Abstract

Objectives: To compare the usefulness of four imaging modalities in visualizing various foreign bodies of different sizes. Methods: Foreign bodies of four sizes (0.5, 1, 2 and 3 mm) including metal, tooth, wood, plastic, stone, glass and graphite were embedded in six fresh sheep heads on bone surface between the corpus mandible and muscle, and inside the tongue muscle. A human dry skull served as an air-filled space. Plain radiography, CT, MRI and ultrasonography were used, and four skilled radiologists rated the findings individually. Results: All embedded foreign bodies except wood were best visualized using CT. Wood could only be detected using ultrasonography, and then only when fragments were >0.5 mm in size. Plain radiography and CT were almost equally accurate in visualizing metal and graphite. MRI was the least useful imaging technique. Conclusions: In cases with suspected foreign bodies in the maxillofacial region, CT seems to be the optimal initial imaging study. Wood, however, could only be detected using ultrasonography.