ORIGINAL CONTRIBUTION computed tomography; radiography; ultrasonography; xerography
Detection of Soft-Tissue Foreign Bodies by Plain Radiography, Xerography, Computed Tomography, and Ultrasonography Michael J Ginsburg, MD, FACEP*t George L Ellis, MD, FACEPI¢ Lynda L Flom, MD§ Pittsburgh, Pennsylvania From the Department of Emergency Medicine, McKeesport Hospital;* University of Pittsburgh Affiliated Residency in Emergency Medicine;t and Departments of Emergency Medicines and Pediatric Radiology§, The Western Pennsylvania Hospital, Pittsburgh. Received for publication July 21, 1989. Revision received November 27, 1989. Accepted for publication February 1, 1990. Presented at the Society for Academic Emergency Medicine Annual Meeting in San Diego,_May 1989. Address for reprints: George L Ellis, MD, FACEE Department of Emergency Medicine, The Western Pennsylvania Hospital, 4800 Friendship Avenue, Pittsburgh, Pennsylvania 15224.
Detection of a soft-tissue foreign body is common yet often difficult, particularly when the foreign material is not radiopaque. Various imaging modalities have been advocated for detecting foreign bodies that are not revealed by plain radiography. The abilities of plain radiography, xerography, computed tomography, and ultrasonography to detect glass, wooden, and plastic foreign bodies in an in vitro preparation are compared. While all of these imaging techniques demonstrated a glass foreign body, only ultrasonography clearly identified wooden and plastic foreign bodies. /Ginsburg MJ, Ellis GL, Flora LL: Detection of soft-tissue foreign bodies by plain radiography, xerography, computed tomography, and ultrasonography. Ann Emerg Med June 1990;19:701-703.] INTRODUCTION Establishing the diagnosis of retained foreign body is frequently difficult. History, physical examination, and plain radiography may not confirm the existence of a foreign body. In a study of more than 200 cases, 38% of foreign bodies were missed on the initial examination, t Complications caused by retained foreign bodies include infections (eg, tetanus, gas gangrene, cellulitis, 2 osteomyelitis, mycetoma,3), peripheral nerve damage, 4 false arterial aneurysm, 5 and synovitis. 6 Infections are common and are caused by direct inoculation, provision of a nidus, and zero oxygen level at the foreign body site. 7 The literature is replete with references to radiologic techniques for foreign body detection. When conventional plain films fail, l~ositive and negative xerography, S,9 c o m p u t e d t o m o g r a p h y {CT),I°, It and" ultrasonographyl2, t3 h a v e all been recommended to detect foreign bodies. Our study was designed to directly compare the abilities of these techniques to detect superficial foreign bodies in an in vitro preparation. METHODS The in vitro preparation consisted of 5 × 2 - m m fragments of wood, glass, and plastic placed at 2.5-cm intervals between two strips of steak that were 3 cm wide x 8 cm long x 1 cm thick. The preparation was submerged in water to minimize any air interfaces between the pieces of steak. Conventional and high-resolution film-screen radiography; xeroradiography in both the positive and negative modes; CT with a 9800 GE CT scanner (General Electric, Milwaukee, Wisconsin) with both bone and soft-tissue windows at 5-ram axial slices; and ultrasonography using the Acuson 10106 (Acuson Corporation, Mountainview, California), a high-resolution linear real-time scanner with a 5-MHz transducer with a focal distance of 38 mm, were used to detect these foreign bodies. RESULTS The glass fragment (Figure, central column) was radiopaque and therefore easily detected by conventional radiography (panel 2), CT (panel 3), and positive and negative xeroradiography (panels 4 and 5). The glass was also detectable with ultrasonography (panel 6) providing a detectable echogenic source with acoustic shadowing. The wooden foreign body (left column) and plastic foreign body (right column) were not detectable with conventional radiography (panel 2}. On
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Wood
Glass
Plastic
Preparation
CT (panel 3), the wooden and plastic fragments produced densities similar to serous fluid or normal soft-tissue variations. The wooden and plastic f r a g m e n t s p r o d u c e d densities on xeroradiography (panels 4 and 5) that could not be clearly distinguished from normal variations with the softtissue preparations. The wooden and plastic foreign bodies produced a detectable echogenic source with acoustic shadowing on ultrasonography (panel 61. The acoustic properties of these three objects were not sufficiently characteristic to determine the composition of the foreign bodies.
Plain Radiography
Computed Tomography
DISCUSSION The time-honored methods for det e c t i n g superficial foreign bodies have limitations. History, physical examination and routine radiography often fail to identify a foreign body. Our study suggests that standard radiography, CT, and xeroradiography are of limited use in foreign body detection if the foreign body is not radiopaque. In our in-vitro study, ultrasonography was the most reliable method for detecting nonradiopaque superficial foreign bodies. Ultrasonography may provide maximum benefit in detecting nonradiopaque superficial foreign bodies when ultrasound transmission is not impeded by overlying air or bone. We suggest using ultrasonography if a superficial foreign body is clinically suspected but not detected on initial conventional radiographs.
Xerography- Positive
Xerography - Negative
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FIGURE. Comparison of plain radiography (panel 2), CT (panel 3), positive and negative xeroradiography (panels 4 and 5), and ultrasonography (panel 6) in imaging wooden, glass, and plastic foreign bodies in an invitro preparation.
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FOREIGN BODY DETECTION Ginsburg, Ellis & Flom
CONCLUSION In an in-vitro study, ultrasonography was the most reliable method for the detection of nonradiopaque superficial foreign bodies composed of wood or plastic when compared with c o n v e n t i o n a l r a d i o g r a p h y , xeroradiography, and CT. Ultrasonography as well as the other modalities accurately detected the radiopaque glass foreign body. REFERENCES 1. Anderson MA, Newmeyer WL, Kilgore ES: Diagnosis and treatment of retained foreign bodies in the band. Am J Surg 1982;144:63-67. 2. Cutler CW: Injuries of the hand by ptmcture wounds and foreign bodies. Surg Clin North Am
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1941;4:485-493. 3. Burkus JK: Primary mycetoma infection of the distal tibia secondary to an occult foreign body. Foot Ankle 1985;6:47-52. 4. Browett JP, Fiddian NJ: Delayed median nerve injury due to retained glass fragments. J Bone Joint Surg 1985;67:382-384. 5. Cohen MA: False (traumatic) aneurysm of the facial artery caused by a foreign body. h~t J Oral Maxillofac Surg 1986;15:336-338. 6. Klein B, McGahan JP: Thorn synovitis: CT diagnosis. J Comput Assist Tomogr 1985; 9:1135-1136.
9. Woesucr ME, Sanders I: Xeroradiography: A significant modality in the detection of nonmetallic foreign bodies in soft tissues. AJR 1972;115:636-640. 10. Knhns LR, Borlaza GS, Seigel RS, et al: An in vitro comparison of computed tomography, xeroradiography, and radiography in the detection of soft tissue foreign bodies. Radiology 1979;132:218-219. 11. Combs AH, Kernek CB, Heck DA: Retained wooden foreign body in the foot detected by computed tomography. Orthopedics 1986; 9:1434-1435.
7. Reed BR, Clark RAF: Cutaneous tissue repair: Practical implications of current knowledge. J Am Acad Dermatol 1985;13:919-941.
12. De Flaviis L, Scaglione P, Delbo P, et ah De tection of foreign bodies in soft tissue: Experi mental conrparison of ultrasonography and xeroradiograpby. J Trauma 1988;28:400-404.
8. Pond GD, Lindsey D: Localization of cactus, glass and other foreign bodies in soft tissues. Ariz Med 1977;34:700-7(12.
13. Gooding GAW, Hardiman T, et al: 8onogra phy of the hand and foot in foreign body detection. J Ultrasound Med 1987;6:441-447.
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