Foreign body detection in musculoskeletal Injuries: A in vitro blinded study comparing sensitivity among digital radiography, ultrasonography, CT and magnetic resonance imaging

Common low-density radiolucent organic objects such as thorns, wood and fish bones account for large percentage of foreign bodies present a diagnostic challenge and are routinely missed. In musculoskeletal Injuries, failure to detect organic foreign bodies can lead to infection and functional morbidity. A universal investigation protocol for foreign body detection is lacking. This study was initiated to compare Digital radiography, CT, MRI and Hi-Frequency ultrasound with respect to suitability for detecting foreign bodies in In-vitro (goat thigh specimens) and to formulate a foreign body detection protocol which is universal and practical to use especially for setups in country like ours. Eight materials selected were wood, plastic, sand, metal (steel), glass, stone, teeth and fiber plastic. Foreign bodies placed into the muscle and bone-muscle interface. Digital radiography, Ultrasonography, CT and MRI imaging methods performed. Conventional radiography is preferred imaging method for radiopaque foreign bodies, which were visualized with all 4 modalities. USG is a useful tool for superficial and deep (within 3 cms) low radiopaque foreign bodies (Wood, sand, fiber plastic). CT is a standard method for imaging and localizing deep foreign bodies because their shape and size are accurately reproduced. MRI has high intra-observer variations, is an expensive tool which might not be available at all the centers and time. Radiography as a primary tool teamed up by Ultrasonography can detect almost all routine foreign bodies. CT/MRI may follow if intervention is planned or information regarding size, orientation and location is desired based on availability. Successful detection requires detailed patient’s information and suspected nature of foreign body or accident site.  Our protocol should guide to successful management of a patient with retained foreign body.