Comparison between Computed Tomography and Ultrasonography in Detecting Foreign Bodies Regarding Their Composition and Depth: An In Vitro Study

Abstract

Statement of the problem: Impaction of foreign bodies in the soft tissues is a sequela of traumatic and penetrating injuries. Such foreign bodies should be removed due to the complications they cause. Patient's history, clinical evaluation and imaging examinations aid in the proper detection and localization of the foreign bodies.

Purpose: The aim of the present study was to compare the sensitivity of computed tomography (CT) and ultrasonography for detecting foreign bodies in in-vitro models simulating facial soft tissues.

Materials and method: Fifty foreign particles with five different compositions including wood, glass, metal, plastic, and stone were embedded in five calf tongues at 1, 2, 3, 4 and 5 cm depths. CT and ultrasonography were compared regarding their capability of detecting and localizing the foreign bodies.

Results: Wood and plastic foreign bodies were demonstrated more clearly on ultrasonography images. High density materials such as metal, stone, and glass were detected with almost the same accuracy on CT and ultrasonography examinations. Visibility of the foreign bodies deteriorated on ultrasonography images as their depth increased; however, CT appearances of the foreign particles were not influenced by their depths.

Conclusion: Ultrasonography is an appropriate technique for detection of foreign bodies especially the ones with low density. Therefore, it seems logical to perform ultrasonography in combination with CT in cases with the suspicion of foreign body impaction.

Keywords: Computed tomography; Foreign body; Ultrasonography.

Figure 1

Metal, stone, wood, glass, and plastic were the foreign bodies used in this experiment.

Figure 2

Arrow points to a wooden foreign body on the ultrasound image.

Figure 3

a: Arrow points to a glass foreign body on the ultrasound image. b: Arrows indicate two glass foreign bodies on the CT image.

Figure 4

a: Arrow points to a metal foreign body on the ultrasound image. b: Arrows indicate two metal foreign bodies on the CT image (The dark streak in the middle of the image is caused by the beam hardening artifacts caused by the presence of bilateral metal particles).

Figure 5

a: Arrow points to a plastic foreign body on the ultrasound image. b: Arrow indicates a plastic foreign body on the CT image.

Figure 6

a: Arrow points to a stone foreign body on the ultrasound image. b: Arrows indicate two stone foreign bodies on the CT image.