title: Not all radiopaque foreign bodies shadow on ultrasound: unexpected sonographic appearance of a radiopaque magnet.
abstract: Foreign body ingestion is a common indication for imaging children. Ultrasound can be a useful adjunct to serial radiographs for evaluation of foreign bodies in the enteric tract. This case report describes a child who swallowed a single magnetic rock. Follow-up radiographs 4 days later could not determine progression of the foreign body beyond the stomach. Ultrasound was used to locate it, showing a structure with unexpected posterior reverberation artifact in the stomach. This was correlated with a similar magnet in a water bath demonstrating identical reverberation artifact. This report discusses the underlying factors for the different sonographic appearances and associated ultrasound artifacts of foreign bodies. This knowledge is important when performing sonography as adjunct modality for identification of foreign bodies in the gastrointestinal tract.
authors.affiliation: Perelman School of Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA.
authors.forename: Sherwin
authors.initials: S
authors.lastname: Shiu-Cheung Chan
authors.forename: Marybeth
authors.initials: M
authors.lastname: Russell
authors.forename: Victor M
authors.initials: VM
authors.lastname: Ho-Fung
mesh_terms: D002648:Child; D020878:Device Removal; D005188:False Negative Reactions; D005547:Foreign Bodies / Q000000981:diagnostic imaging* / Q000601:surgery; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging* / Q000293:injuries* / Q000601:surgery; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D059346:Magnets; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014463:Ultrasonography / Q000379:methods*