Comparison of Cone Beam Computed Tomography and ultrasonography with two types of probes in the detection of opaque and non-opaque foreign bodies

The aim of this study was to compare the diagnostic accuracy of intra-oral and extra-oral ultrasonographic (US) examinations performed with linear and convex probes in the detection of opaque and non-opaque foreign bodies (FBs) located in the maxillofacial area. Thirteen different type of FBs were inserted into a sheep's head: a) on the external bone surface of mandible (between the mandibular corpus and masseter muscle), b) in the intrinsic muscular tissue (in the dorsum of the tongue) and c) in the hollow structures (into the maxillary sinus of the sheep's head). The FBs in muscle tissue were scanned intra-orally whereas FBs in bone external bone surface of mandible and in maxillary sinus were scanned both intra-orally and extra-orally. The sensitivity of cone beam computed tomography (CBCT) and US imaging methods in detection of FBs were compared for FBs on the bone surface and in the muscular tissue. The intra-observer kappa coefficients provided identical values of 0.236 for the extra-oral convex probe, 0.461 for the intra-oral linear probe for overall FBs detection, which indicated notably poor to fair intra-observer agreement. The inter-observer agreement showed a poor agreement for the extra-oral use of linear probe (0.341 and 0.393) and extra-oral use of convex probe (0.319 and 0.335), However, a fair agreement was determined for use of probe intra-orally (0.530 and 0.534). Overall, the diagnostic accuracy of the CBCT was higher than the US regarding the visualization of FBs in the bone tissue. US with a linear probe should be the first choice for the detection of the low-radiodensity FBs, which are entrapped in the soft tissue. However, CBCT is a more sensitive technique for the visualization of FBs in air and bone tissue compared to the US, particularly for the diagnosis of high-radiodensity FBs.